Coordination by Ajai Kumar.pdf
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About This Presentation
Coordination chemistry
Slide Content
AJAI KUMAR
Assistant Professor
Department of Chemistry
Hindu College, University of Dei
Det
AARYUSH EDUCATIONS
8-32, Ground Floor, DEF, Ankur Vihar
© Ghaziatiad (U.P)
ici AE
Assistant Professor
Department of Chemistry
Hindu College, University of Dei
Det
AARYUSH EDUCATIONS
8-32, Ground Floor, DEF, Ankur Vihar
© Ghaziatiad (U.P)
ici AE
dial ade dnu cor a nah
0 ünen petalos we dad Wan Lape ao.
Wu. ethene Mare - verge
a.
?
5,47 À
Co, Oy, Gs st ea) a fora 326 bend
in rebuss
nn, 813715 > : À à o à
en ; > Tom my ‘PARENTS’
09457640709:
NAN, UP a a cata obewdile
© Aut
ae Da E NN > of” —AjaiKumar
Fu exp Pe Eine alone act puved
dub zafubin (unge)
25 pul “o, 90 Bab) À cad
pr fl foo Spin oh) ,
‘Second Edition: 2014
Design by :
Prakash Graphics
PRICE : {350
Ro par of his book may be eproducad in a retival system or transmits, in any form or y
any means cecrnis, mechanical photocopying, recording and/or hou permission othe
Auihorpublshers.
0 ünen petalos we dad Wan Lape ao.
Wu. ethene Mare - verge
a.
?
5,47 À
Co, Oy, Gs st ea) a fora 326 bend
in rebuss
nn, 813715 > : À à o à
en ; > Tom my ‘PARENTS’
09457640709:
NAN, UP a a cata obewdile
© Aut
ae Da E NN > of” —AjaiKumar
Fu exp Pe Eine alone act puved
dub zafubin (unge)
25 pul “o, 90 Bab) À cad
pr fl foo Spin oh) ,
‘Second Edition: 2014
Design by :
Prakash Graphics
PRICE : {350
Ro par of his book may be eproducad in a retival system or transmits, in any form or y
any means cecrnis, mechanical photocopying, recording and/or hou permission othe
Auihorpublshers.
An this book [have attempted to highlight he concepts of Coordination
* Compounds relevant to students of undereradiic and postgraduate levels
‘of all indian universities, Y have write this Book in a readable and easily.
a ‘understandable way. Numerous examples are provided throughout the text.
willbe invaluable to teaching, and teaming dosent of coordination 7": EM + tn etext, have incorporated the chan loe ules made for the
chemistry. [also feel pleasure that this book is written by my colleague. We nomenclature of coordination compours. by_the IUPAC in the latest
5 À eda EE 22 on of 2005. have given the deal description of sometsm (maialy
(aiyslf, Aji Kumar and Meenu Srivastava) normal share and discuss the ey eat eee ai mail
fundamentals of inorganic chemistry including coordination chemistry 4 © and anion both as complex ions), bondink theôrié, magueti properties,
‘when we are in laboratory, staTioomór the teacher's oom. ie “colour and electronic spectra, stability and reaction mechanism. E felt that
‘The question, fill in the blanks, objective and subjective have the +!" ithe students face the various problems regarding the fundamentals of
levels of various competition exams like IT JAM, CSIR-UGC GRFINET), 4 coordination chemistry. Therefore, I had decided to write the book on
E IR. DRS ONCE NAPOENERG oof Ths © fundathentals of coordination chemistry.
GATE, IISc, BARC, TIFR, DRDO, ONGC, a + T hope that this book will be very helpful for the aspirants of all
fundaniehtals of coordination chemistry are vite according tothe need 5 ‘competitive exams related to chemistry like IT-JAM, CSIR-UGC
‘ofthe students. I wish that this book may give a way ofsuresuccess. 7. (NET/IRF),GATE, TIFR, BARC, IISc, DRDO, ONGC, NTPCetc.
# is Thave incorporated large number of objective questions asked in the
past competitive exams to know the Level of question paper for future
tive examinations. The category “Fill in the blanks” are especiall
Den Aa forthe aspirants: ofl. JAMexamitaion, id
Thavetaken particular care o ensure hatthetextisfreeofemos.
Da thank to Mr, Prakash Arora for designing and giving a good look to the
Hindu College; book. I thanks to Mr. Anil Goriyan whose efforts made the completion of
University ofDethi úisbook.
Delhi a Texpress my sincere thanks to my daughter-Little, my son-Aaryush
and my wife-Mrs. Archana and my other family members.
also thank to Dr. Meena Srivastava, Dr. Sudarshan and Dr. Raghvi
Khaitarfortbeir constructive suggestions.
Ca learner found any error in the text please send your constructive
‘criticism aad suggestions to update the book time to time. The critics will
22. be gratefully received and acknowledge.
L feel pleasure to introduce this book. The content given inthe book ©.
Associate Professor
—AjalKumar
15-Noy-2012.
[email protected]
* Compounds relevant to students of undereradiic and postgraduate levels
‘of all indian universities, Y have write this Book in a readable and easily.
a ‘understandable way. Numerous examples are provided throughout the text.
willbe invaluable to teaching, and teaming dosent of coordination 7": EM + tn etext, have incorporated the chan loe ules made for the
chemistry. [also feel pleasure that this book is written by my colleague. We nomenclature of coordination compours. by_the IUPAC in the latest
5 À eda EE 22 on of 2005. have given the deal description of sometsm (maialy
(aiyslf, Aji Kumar and Meenu Srivastava) normal share and discuss the ey eat eee ai mail
fundamentals of inorganic chemistry including coordination chemistry 4 © and anion both as complex ions), bondink theôrié, magueti properties,
‘when we are in laboratory, staTioomór the teacher's oom. ie “colour and electronic spectra, stability and reaction mechanism. E felt that
‘The question, fill in the blanks, objective and subjective have the +!" ithe students face the various problems regarding the fundamentals of
levels of various competition exams like IT JAM, CSIR-UGC GRFINET), 4 coordination chemistry. Therefore, I had decided to write the book on
E IR. DRS ONCE NAPOENERG oof Ths © fundathentals of coordination chemistry.
GATE, IISc, BARC, TIFR, DRDO, ONGC, a + T hope that this book will be very helpful for the aspirants of all
fundaniehtals of coordination chemistry are vite according tothe need 5 ‘competitive exams related to chemistry like IT-JAM, CSIR-UGC
‘ofthe students. I wish that this book may give a way ofsuresuccess. 7. (NET/IRF),GATE, TIFR, BARC, IISc, DRDO, ONGC, NTPCetc.
# is Thave incorporated large number of objective questions asked in the
past competitive exams to know the Level of question paper for future
tive examinations. The category “Fill in the blanks” are especiall
Den Aa forthe aspirants: ofl. JAMexamitaion, id
Thavetaken particular care o ensure hatthetextisfreeofemos.
Da thank to Mr, Prakash Arora for designing and giving a good look to the
Hindu College; book. I thanks to Mr. Anil Goriyan whose efforts made the completion of
University ofDethi úisbook.
Delhi a Texpress my sincere thanks to my daughter-Little, my son-Aaryush
and my wife-Mrs. Archana and my other family members.
also thank to Dr. Meena Srivastava, Dr. Sudarshan and Dr. Raghvi
Khaitarfortbeir constructive suggestions.
Ca learner found any error in the text please send your constructive
‘criticism aad suggestions to update the book time to time. The critics will
22. be gratefully received and acknowledge.
L feel pleasure to introduce this book. The content given inthe book ©.
Associate Professor
—AjalKumar
15-Noy-2012.
[email protected]
CONTENT
Coordination Chemistry
pe Ties paso able econ es and
In this edition som objective and subjective questions are added Gaines
do
An Introduction to Coordination Compounds
| Compounds, by electron ee if
pe ati new tion il Structure and IsomerisminCäordnationCompounds 2.12.44
LUFACHomeriecfCoodaionConpounds 31-348
4. Theories for Metak-Ligand Bonding Complexes 4.1-4.60
5. Colourand Electronic Spectra 51-566
6. Magnetism - 61-618
it aleamie fo
“criticism and suggestions 16 updat ve hebook ine lot. The ritieism will:
$ 2 Stablity of Complexes and Reaction Mechanism
Coordination Chemistry
pe Ties paso able econ es and
In this edition som objective and subjective questions are added Gaines
do
An Introduction to Coordination Compounds
| Compounds, by electron ee if
pe ati new tion il Structure and IsomerisminCäordnationCompounds 2.12.44
LUFACHomeriecfCoodaionConpounds 31-348
4. Theories for Metak-Ligand Bonding Complexes 4.1-4.60
5. Colourand Electronic Spectra 51-566
6. Magnetism - 61-618
it aleamie fo
“criticism and suggestions 16 updat ve hebook ine lot. The ritieism will:
$ 2 Stablity of Complexes and Reaction Mechanism
Me at &
AD |b sue du
oe al me
Au dise ode
ire SU
EA
NO, cable he
NG” Not ambidudats,
UN doit Seale ay cmbidout
Any species (ion rmotecale) tat havealeat one one pair of electrons and hat can dat its ane
pair of electons toa mea con o stom called a and. Since a igand is an leon rich species,
therefore, itis also called a Leyisbas ra muclepphile. A metal cation isan electron deficient species
and tear accept par of elactons, ore, a metal ation behaves as a Lewis acid oran lectopi.
‘When a group of ligends donates its pats of electrons (one par by one donor atom of izand) tthe
ame cation or atom coordinate bonds ae ome and the product so formed i called x coodinaion
compound. Thus, «compound in which a meal cation or atom is attached to a group of ligands by
coordinate bonds à calle à cuen compound or complex compound. The nenn
compounds may ether be neutral molecules rio compounds. The compounds ik [PL(NE Cla}
A
(Cost) are entra ooeinton compounds. In ionic coordination compounds ite hecstion
cor anion or both may be complex ons. For example, [Co(NH Je 1C13 contains [Co(NHLJg]"* as
complex cation, K,(Fe(CM)s] contains [Fe(CN)s1Ÿ as complex anion and {Pt (NH) PCI]
contains {P(NHs)¢]?* and [PIC as complex ions ¿e, complex cation and complex wien
respectively. The coordination compo ein thei entity, more or less even n solution, tough
partial dissociation may occu. These compound do RoC ge the test of all hex Coste ons in
Aqucous SOTO LE, ¿ONES sons lo her indica! identities in aqueous son Foe
«example (CO(NH Je C1 is complex compound and it does ot give he tex ofall ie constuenion,
Co and C1” instead it gives theCo™ as{CO(NHG)¢* complex ion and CI” ions
‘A comple ion sa on in which mea cation is atched to ligands by coordinate bonds.
Coordination chemisty isthe branch of inorganic chemistry which concems the sty of
coordination compounds. 5
In the structural formula of corination compound, te central metal ction o ato and e
tigend attached to it are writen ina square brake, { which is called a coordination spre Thecaion
‘oF anion out side the coordination sphere scale he jonzation sphere or counter on.
‘The atom in ig ts ei tached tothe metal cation o atom is called the dosor atom and
the number of donor atoms attached to meal cation or atom is called the coordination number. For
example, coordination number of Ag" in (Ag (NH 2]?* is2, that of Cu? in [Ca(NH ha)" is and
that of Co in [Co(NHs)e}* is 6,
AD |b sue du
oe al me
Au dise ode
ire SU
EA
NO, cable he
NG” Not ambidudats,
UN doit Seale ay cmbidout
Any species (ion rmotecale) tat havealeat one one pair of electrons and hat can dat its ane
pair of electons toa mea con o stom called a and. Since a igand is an leon rich species,
therefore, itis also called a Leyisbas ra muclepphile. A metal cation isan electron deficient species
and tear accept par of elactons, ore, a metal ation behaves as a Lewis acid oran lectopi.
‘When a group of ligends donates its pats of electrons (one par by one donor atom of izand) tthe
ame cation or atom coordinate bonds ae ome and the product so formed i called x coodinaion
compound. Thus, «compound in which a meal cation or atom is attached to a group of ligands by
coordinate bonds à calle à cuen compound or complex compound. The nenn
compounds may ether be neutral molecules rio compounds. The compounds ik [PL(NE Cla}
A
(Cost) are entra ooeinton compounds. In ionic coordination compounds ite hecstion
cor anion or both may be complex ons. For example, [Co(NH Je 1C13 contains [Co(NHLJg]"* as
complex cation, K,(Fe(CM)s] contains [Fe(CN)s1Ÿ as complex anion and {Pt (NH) PCI]
contains {P(NHs)¢]?* and [PIC as complex ions ¿e, complex cation and complex wien
respectively. The coordination compo ein thei entity, more or less even n solution, tough
partial dissociation may occu. These compound do RoC ge the test of all hex Coste ons in
Aqucous SOTO LE, ¿ONES sons lo her indica! identities in aqueous son Foe
«example (CO(NH Je C1 is complex compound and it does ot give he tex ofall ie constuenion,
Co and C1” instead it gives theCo™ as{CO(NHG)¢* complex ion and CI” ions
‘A comple ion sa on in which mea cation is atched to ligands by coordinate bonds.
Coordination chemisty isthe branch of inorganic chemistry which concems the sty of
coordination compounds. 5
In the structural formula of corination compound, te central metal ction o ato and e
tigend attached to it are writen ina square brake, { which is called a coordination spre Thecaion
‘oF anion out side the coordination sphere scale he jonzation sphere or counter on.
‘The atom in ig ts ei tached tothe metal cation o atom is called the dosor atom and
the number of donor atoms attached to meal cation or atom is called the coordination number. For
example, coordination number of Ag" in (Ag (NH 2]?* is2, that of Cu? in [Ca(NH ha)" is and
that of Co in [Co(NHs)e}* is 6,
EEE
EB
Barmen
“The term discussed above ar shown below:
[SSR
‘Cental metal ation”
Ligands
Ionization sphere
Coordination number
Coordination sphere
wi ;R’S THEORY:
In 1893 Werner produced a theory of coordination compounds to explain the sches and
nation of compounds. Werner was the fist inorganic chemist to be avarded the Noble prize for
nist in 1913. Werner postulate that metals exhibit two types of valenies : (1) Primary valency
(2) secondary valeny. In modern terminology, primary valency coresponds o the oxidation
bec and secondary valency to coordination number of metal.
Timlin nm coa Te ray wie ey
pegative ons ain simple sa NETT,
Prima
y valeney of cobalt in [CO(NH 6 Cl, Co (NM) CC, (CON CIJ and
15) 1 complex is + 3 and is sata by three CI” ions, The aions which say only
uy valency are writen out side he cordinaion sphere. Te nions may sat pinar as wells
dary valence of etal. The anions which sas bot primary and secondary vlences ae placed
te the cocediaton sphere. The anions sas the primary valency do ot give any geomety o
hple compound. When he compound undergoes ionization in aqueous solution, the anions which
ey only primary valency are bin. For example, when CoCl AN undergoes imizao in
cous solution, tre CI ions which satisfy primary vleney are obtained
The secondary or auiiay valencies of mel are sated iter by negative ions oF metal
ecules or both. Inthe structure ofeoordintion compounds he metal cation ndthe speissaisiog
secondary valence are pce inside the coordination sphere. The species sting secondary
ies ae nt baie in quen solo in free state instezd complex in is obtsned, The
ary valence ar deed in space gie finit geomaty tothe comple. The eometies of
plexes comesponding to, 3,4 and secondary vlencie ar inca, goal planar, ada or
ase plana and octal respective
Werner studied he strstr nd propenis ofthe following fourcomplexes ofl) oid wid
aia which Have int colors
IR RE ONT
7
a
|
Table 11: Complexes of Coll) Chloride with Ammonia
‘CoCts -6NH | ICONE: «IC Yellow 1 I fa
CoCly -SNHy |ICOMMHS) CHC, | Purple 1 2 13
CoC “ANH | Trans Green ı i.
Keinen)
CoC ly -4NH | is-[CO(NH3)4CI2JCI | Violet tor a
oct} -3NHs | [CoCMHS)sCh] Blue | — = = Life
green
Wemerteaed th fist four complexes of Coll) given in Table 1.1 withan excess OF ARNO, The
white precipitate of AgCl wee obtained in different amount
CORNE
Coby -5N TE ager
CaCl, anh FE, gc
Werner reported that nCoCls «ONE all the three chlorides satisfy only primary valency and thesix
ammonia molecules stisy only the secondary vaiency. The primary valencies represented by dotted
lines (..) and secondary valencies are represented by sc (The structure of CoC; ONE 5
shown in Figure 1.(). This compound in aqueous solution gives total number fouriors a, tree CI”
and one Co(NH 61°" ons. Thus, in modem term this compound is writen as (Co(NH Cl. Wien
this compounds treated with an excess of AgNO solution al three CI ions are prit as Al
[ONE — [CN EP" +7
Bag’ 4307 ——> 349169)
I CoOls «SNH, the primary and the secondary valencies of cobalt ae three and six respectively.
All the three primary valenciesaestisfied by three chloride ions. Out of sx secondary valencies, five
are satisfied by amonis molecules andthe sixth by one ofthe chloride ions, Therefore one chloride on
exhibit double duty a it satisfy a primary as well as a secondary valency and itis represented as
line, {Figure 1.1). When his compourd is treated with an excess of AgNO, solution, oly two
chloride ins are precipitated as ABC.
EB
Barmen
“The term discussed above ar shown below:
[SSR
‘Cental metal ation”
Ligands
Ionization sphere
Coordination number
Coordination sphere
wi ;R’S THEORY:
In 1893 Werner produced a theory of coordination compounds to explain the sches and
nation of compounds. Werner was the fist inorganic chemist to be avarded the Noble prize for
nist in 1913. Werner postulate that metals exhibit two types of valenies : (1) Primary valency
(2) secondary valeny. In modern terminology, primary valency coresponds o the oxidation
bec and secondary valency to coordination number of metal.
Timlin nm coa Te ray wie ey
pegative ons ain simple sa NETT,
Prima
y valeney of cobalt in [CO(NH 6 Cl, Co (NM) CC, (CON CIJ and
15) 1 complex is + 3 and is sata by three CI” ions, The aions which say only
uy valency are writen out side he cordinaion sphere. Te nions may sat pinar as wells
dary valence of etal. The anions which sas bot primary and secondary vlences ae placed
te the cocediaton sphere. The anions sas the primary valency do ot give any geomety o
hple compound. When he compound undergoes ionization in aqueous solution, the anions which
ey only primary valency are bin. For example, when CoCl AN undergoes imizao in
cous solution, tre CI ions which satisfy primary vleney are obtained
The secondary or auiiay valencies of mel are sated iter by negative ions oF metal
ecules or both. Inthe structure ofeoordintion compounds he metal cation ndthe speissaisiog
secondary valence are pce inside the coordination sphere. The species sting secondary
ies ae nt baie in quen solo in free state instezd complex in is obtsned, The
ary valence ar deed in space gie finit geomaty tothe comple. The eometies of
plexes comesponding to, 3,4 and secondary vlencie ar inca, goal planar, ada or
ase plana and octal respective
Werner studied he strstr nd propenis ofthe following fourcomplexes ofl) oid wid
aia which Have int colors
IR RE ONT
7
a
|
Table 11: Complexes of Coll) Chloride with Ammonia
‘CoCts -6NH | ICONE: «IC Yellow 1 I fa
CoCly -SNHy |ICOMMHS) CHC, | Purple 1 2 13
CoC “ANH | Trans Green ı i.
Keinen)
CoC ly -4NH | is-[CO(NH3)4CI2JCI | Violet tor a
oct} -3NHs | [CoCMHS)sCh] Blue | — = = Life
green
Wemerteaed th fist four complexes of Coll) given in Table 1.1 withan excess OF ARNO, The
white precipitate of AgCl wee obtained in different amount
CORNE
Coby -5N TE ager
CaCl, anh FE, gc
Werner reported that nCoCls «ONE all the three chlorides satisfy only primary valency and thesix
ammonia molecules stisy only the secondary vaiency. The primary valencies represented by dotted
lines (..) and secondary valencies are represented by sc (The structure of CoC; ONE 5
shown in Figure 1.(). This compound in aqueous solution gives total number fouriors a, tree CI”
and one Co(NH 61°" ons. Thus, in modem term this compound is writen as (Co(NH Cl. Wien
this compounds treated with an excess of AgNO solution al three CI ions are prit as Al
[ONE — [CN EP" +7
Bag’ 4307 ——> 349169)
I CoOls «SNH, the primary and the secondary valencies of cobalt ae three and six respectively.
All the three primary valenciesaestisfied by three chloride ions. Out of sx secondary valencies, five
are satisfied by amonis molecules andthe sixth by one ofthe chloride ions, Therefore one chloride on
exhibit double duty a it satisfy a primary as well as a secondary valency and itis represented as
line, {Figure 1.1). When his compourd is treated with an excess of AgNO, solution, oly two
chloride ins are precipitated as ABC.
EPR E Colin Cry,
{Co(NHs)sCI}Ch, — (CNE) +20
2Ag* 200 — 2A)
‘This indicate the” ons which satsyonly the pay valence are ionizabi. In aqueos
solution total numberof thee ous are obtained, one [Oo (NH); CIF and oC” ions. ln modern
fem is compound is weten as [Co (NH) CICL. The serre of Co(NH)sCCl is shown in
Figure LI)
InCoCis-4NH,, the primary and secondary valencies of cobalt are 3 and 6 respectively. All the
three primary valecie are said by thre chloride ions. Out of six secondary valence, four ace
sais by anmonia molecules and fifth and sixth by two ofthe thee chloride ons. Ths, vo chloride
ions exhibit double duty of satisfying primary as well as secondary valecis. When this compound is.
treated with en excess of ANOS solution, only one chloride ion is precipitated as AgCl. In aqueous
solution his compourd gives total number of ve ions Le, one (Co(NH)yClz]'andoneC1 ion. This
compound is writen as [Co(NEI,)«CizJCL The struct of this compound chown in Figure 1.1).
TC ON; Ja Clz JCi-—— [Co(NA5)4 Cla]? «Cr
Ag’ cr — Asc
Se EHRE
CCI INN, primary and the secondary valencits of obal ar tree and sx respectively. Al
the the primar valencies are satisfied by thre chloride ions. Out of six secondary valenies thre are
said by tree ammonia molecules and tee by code fons ns compound the chloride ions
satisfy primary as well as secondary valencies, This compound does at give any precipitate with
‘AgNO, solution, Ths compound is «neutral molecule rd doesnot give ny ion in aqueous solution. In
‘modem term ths compound is written as (Co (NE )5Ch } The structure of his compound is shown in
Figure Lil)
‘Werner alo temple to find the geometries of somes of be comple of Cot), CHI), CID,
Pu ct. The vaous geometries for complexes of condition o. 6 re hexagonal plenr, tonal
prismatic and ocabodal Figure 1.2).
C] al
eur. 12 (0) Heranonel O) Tiporal pre) cab
“The possible isomers for he amınine complexes of C(I for ll he three geometries are given in
the uble 12:
Table 1.2: Possible Isomers of Col) Complexes
IT A Ex
here yet 2 Observe
Hexagonal Plana | Trigoial Pesado] Ë
LUNA i 1 1 1
AC) CR 1 1 1 1
LAN 3 3 2 2
{Co} C1 3 3 2 2
Consider the coordination compound {Co(NH 41g JC. Wem suggested that this compound
may exis in thee possible geomerres Le, hexagonal planar, trigonal prismatic and octahedral. The
posible isomers comesponding to these geometes re thee, thre and two respectively as shown in
Figure 13.
{Co(NHs)sCI}Ch, — (CNE) +20
2Ag* 200 — 2A)
‘This indicate the” ons which satsyonly the pay valence are ionizabi. In aqueos
solution total numberof thee ous are obtained, one [Oo (NH); CIF and oC” ions. ln modern
fem is compound is weten as [Co (NH) CICL. The serre of Co(NH)sCCl is shown in
Figure LI)
InCoCis-4NH,, the primary and secondary valencies of cobalt are 3 and 6 respectively. All the
three primary valecie are said by thre chloride ions. Out of six secondary valence, four ace
sais by anmonia molecules and fifth and sixth by two ofthe thee chloride ons. Ths, vo chloride
ions exhibit double duty of satisfying primary as well as secondary valecis. When this compound is.
treated with en excess of ANOS solution, only one chloride ion is precipitated as AgCl. In aqueous
solution his compourd gives total number of ve ions Le, one (Co(NH)yClz]'andoneC1 ion. This
compound is writen as [Co(NEI,)«CizJCL The struct of this compound chown in Figure 1.1).
TC ON; Ja Clz JCi-—— [Co(NA5)4 Cla]? «Cr
Ag’ cr — Asc
Se EHRE
CCI INN, primary and the secondary valencits of obal ar tree and sx respectively. Al
the the primar valencies are satisfied by thre chloride ions. Out of six secondary valenies thre are
said by tree ammonia molecules and tee by code fons ns compound the chloride ions
satisfy primary as well as secondary valencies, This compound does at give any precipitate with
‘AgNO, solution, Ths compound is «neutral molecule rd doesnot give ny ion in aqueous solution. In
‘modem term ths compound is written as (Co (NE )5Ch } The structure of his compound is shown in
Figure Lil)
‘Werner alo temple to find the geometries of somes of be comple of Cot), CHI), CID,
Pu ct. The vaous geometries for complexes of condition o. 6 re hexagonal plenr, tonal
prismatic and ocabodal Figure 1.2).
C] al
eur. 12 (0) Heranonel O) Tiporal pre) cab
“The possible isomers for he amınine complexes of C(I for ll he three geometries are given in
the uble 12:
Table 1.2: Possible Isomers of Col) Complexes
IT A Ex
here yet 2 Observe
Hexagonal Plana | Trigoial Pesado] Ë
LUNA i 1 1 1
AC) CR 1 1 1 1
LAN 3 3 2 2
{Co} C1 3 3 2 2
Consider the coordination compound {Co(NH 41g JC. Wem suggested that this compound
may exis in thee possible geomerres Le, hexagonal planar, trigonal prismatic and octahedral. The
posible isomers comesponding to these geometes re thee, thre and two respectively as shown in
Figure 13.
even
ay : "in
Figure 13 (6) Tu post cd pray
Only two isomers of compound [Co(NH3)4Cl, JC has been isolated which correspond to the
Elatedral geometry. Thus, in these isomers the arrangement of ligands round the metal cation is
‘heal. Wemer conctuded that the complexes of coordination number 6 are octahedral
¡Werner also suggested that the coordination compounds with coordination number 4 exhibit two
sie geometies Le, square planar and tetrahedral
Ja sinon compound PE; Ci, cordon number and dis compound exis
Ware planar geometry. Two isomers cis- and ¿vans [Pt(NH3)2 Cl: has been isolated for this
ompoutd (Figure 14). AE
Ai pi |
estate ete
ee
SL Lune
a
emer also suggested that in tetrahedral complexes only one arrangement is possible round the
mel ation.
Evidence in Favour of Wemer's Theory
(1) Electrical Conductance Measurement : Molar conductance Of a substance depends upon the
number of charges on the particles fumished by the substance in aqueous sation. As the number of
parcs (Le, ions) and charges on them increases the molar conductance of the compound increases
‘Theobserved molar conductance for agueous solutions of cobalI) chloride complexes with ammonia
creases inthe order E
[Co(NH Je JC > [Co (NH) sC]Ctz > (Cals aClz ICI> [COCNH )3Cls}
‘This indicates thatthe number of ios andthe number of charges decrease inthe same order as
shown in the table 1.3 The molar conductance meusurement of Co(lI) chloride complexes with
‘ammonia suggest the structures similar to structures suggested by Werner.
Table 1.3 : Elucidation of Structure of Coll and PH) Complexes on the Basis of
‘Conductance and Cryascopic Measurements.
TREE,
from Conductance 3
Mensutement |. Measurements 8
CoC; “NH 4 Sr [Co(NH 153007
Coty SNH 3 462-D CAMES
CoC ANH 2 264-0 COUTANCES
CET o a [Co(NH3)Cla)
PCI, NE 5 s64-D CINE"
DICK «SNE 4 5-0 CT ARE.
PC ANS 3 462-D (Peavy CL ac"
PEINE 5 26 2-0 LIST JCH Or
PC -2NHy o o LP D} Cha?
ay : "in
Figure 13 (6) Tu post cd pray
Only two isomers of compound [Co(NH3)4Cl, JC has been isolated which correspond to the
Elatedral geometry. Thus, in these isomers the arrangement of ligands round the metal cation is
‘heal. Wemer conctuded that the complexes of coordination number 6 are octahedral
¡Werner also suggested that the coordination compounds with coordination number 4 exhibit two
sie geometies Le, square planar and tetrahedral
Ja sinon compound PE; Ci, cordon number and dis compound exis
Ware planar geometry. Two isomers cis- and ¿vans [Pt(NH3)2 Cl: has been isolated for this
ompoutd (Figure 14). AE
Ai pi |
estate ete
ee
SL Lune
a
emer also suggested that in tetrahedral complexes only one arrangement is possible round the
mel ation.
Evidence in Favour of Wemer's Theory
(1) Electrical Conductance Measurement : Molar conductance Of a substance depends upon the
number of charges on the particles fumished by the substance in aqueous sation. As the number of
parcs (Le, ions) and charges on them increases the molar conductance of the compound increases
‘Theobserved molar conductance for agueous solutions of cobalI) chloride complexes with ammonia
creases inthe order E
[Co(NH Je JC > [Co (NH) sC]Ctz > (Cals aClz ICI> [COCNH )3Cls}
‘This indicates thatthe number of ios andthe number of charges decrease inthe same order as
shown in the table 1.3 The molar conductance meusurement of Co(lI) chloride complexes with
‘ammonia suggest the structures similar to structures suggested by Werner.
Table 1.3 : Elucidation of Structure of Coll and PH) Complexes on the Basis of
‘Conductance and Cryascopic Measurements.
TREE,
from Conductance 3
Mensutement |. Measurements 8
CoC; “NH 4 Sr [Co(NH 153007
Coty SNH 3 462-D CAMES
CoC ANH 2 264-0 COUTANCES
CET o a [Co(NH3)Cla)
PCI, NE 5 s64-D CINE"
DICK «SNE 4 5-0 CT ARE.
PC ANS 3 462-D (Peavy CL ac"
PEINE 5 26 2-0 LIST JCH Or
PC -2NHy o o LP D} Cha?
escple Meavurereat : Ts deso I ening point 2 coigaiv proper and
eh ann re unbe of pari int ton DORE
Se ir pa aspect ct ja aaa
RS Be el er Un, ee eee
RL ange re elo malena Ge, mesenen of reson a
tig pom) gs e mo fs bl ye ec can cmp le
E cazan ie dut Col CHC, Sy and CaCl AN, dnt 10
a oes reine abre; DN reas union ee be 13. )
relation ecos: resume ins mit by odio conpoan plo
de mel by pcs radins When de emplne Goch GN, CA SM ed
EAN a url ihn ses AO, ln he number ol Nori ins peed
Ba 2nd respecte}. Tiina thi be number orion in orten sre
35 md Teper The cams oie y pipa ection a sl aspen by
Were Te Comples Cl SNS eso coil wh MNO} soln Ths nite atl
th ee ons ar penn ithe xan is compo,
Beeonic pec (UV. vil and y petscopy a the recent nea deine he
ne fentes Becton spec pre br fora aout the energie fois stapes
Coplas (2, eter te compet i eel or ind acid or tea. Kay
peroo giveth formal the seu o compl, bond lens and Bod an
Meg mamen messenen et he ifomatan sot compas eft te compl
teeta or que plana o cbc, 5
Sig Concept of Corda Band
Acadie to Sigil’ concep e ods date ron pars 1 the mel cin or atom
celia te formato of ect hoben cala pds wich pr as
M «-L, Therefore, the complex ion, (Co(NH3)g]”* can be written as.
mal
Ha Ms
NU
wy | Nes
te
The donation of a lesen pi y Nsom of Ny bas been represent by tae The
coordinate Don is very aro coven bond
ations of Sigwick's Concept: The donation of one lern pr by ech ligt the
ental metal cation ato M Léon os case escalation afaegatveclagean
He central cl ai or atom, Du 0 soma of negative charge on he mel ction oro a
part one character etd he complexing ies le
According to Pauling's electronentrality principle, the metaltigznd bonds have some ionic
anse. T preven ihe accoulaton of eave charg on metal cation or lm, he bond ai
¿files mus be ace moe story dono so o the ligando or In ao he
Bord there should be mel and bonding
Effective Atomic Number (EAN) Rule: Te eve sonic number of meta caton or atom ina
comple i the sum of electons on mal ad the losen donated by the ligands. Acocng lo
Sig's re tie cr EAN} EAN fm qua si umber abet
inert gas ie, equal to 36 (KA, St (Xe) ar 86 (Rx), For example, EAN of {Co(NHs)g}™* can be
calculated as follows
Number ofelechons on Coatom=27 "
Number of electrons on Co jon = 27 ~3 = 24
[Number of electron donate y six NH ligands =2 x 6 12
EAN of Co™ in CofNH1s)g]* = 24 +12= 36
An altemate and moe general nl se 18 lctron rate. According oti ue, in a complex the
sam of valence eletons and the electrons donated by the ligands is 1, It provides a closed and sabe
configuration, ns? (=D! np“
or example: For [Co (NE) +
Valence shell econ oniguraon of Co =347 4?
‘Valence shell electronic configuration of Co™* =34% 45°
Number ofeecrons in valence heil ofCo™ = 6
Number of elecson donated by six NHy molecules = 2 6 = 12
‘Number of valence lctensin{Co(NHs)g}** =6+12 =180"
‘The complexes which fellow the EAN os 18 electron ule are considered to be subl. EAN and 1
electron rules are similar but the 18 leon rule is more advantageous because there is no ned 10)
remember the aomi numberof each noble gs. However, there are some exceptions which obey
neither EAN nor 18 eeiro rue, The complexes ia which the metal ations o atoms eve dd mu
of electrons never obey the EAN rule o 8 elec rule because the sum of toa lcrons or valenc
shell electrons andthe electrons dont by the ligand also an odd number For example consider the
complex Fe (CN)
For EAN Rale:
Number ofelectas on Fe atom = 26
Nurberof electron on Fe** ion = 23
‘Number of electri donated by sx CN ligands = 2 x 6= 12
EAN Ge (ONG) = 23 + 12 35
“Thus,(Fe(CNJ6]”” does not obey EAN rule.
For 18 Electron Rule:
‘Valence shell electronic configuration of Fe atom = 34° 45?
‘Valence shell electronic configuration of Fe** ion =34%
‘Number of lence een in Fe? ion
Number of eletondonsted by six CN ligands =2 x 6 = 12
Number of valence elesronsinfF{CN).¢]?- = $41
‘Thus, (Fe(CN} 4]? doesnot obey the 18 electron rule.
7
eh ann re unbe of pari int ton DORE
Se ir pa aspect ct ja aaa
RS Be el er Un, ee eee
RL ange re elo malena Ge, mesenen of reson a
tig pom) gs e mo fs bl ye ec can cmp le
E cazan ie dut Col CHC, Sy and CaCl AN, dnt 10
a oes reine abre; DN reas union ee be 13. )
relation ecos: resume ins mit by odio conpoan plo
de mel by pcs radins When de emplne Goch GN, CA SM ed
EAN a url ihn ses AO, ln he number ol Nori ins peed
Ba 2nd respecte}. Tiina thi be number orion in orten sre
35 md Teper The cams oie y pipa ection a sl aspen by
Were Te Comples Cl SNS eso coil wh MNO} soln Ths nite atl
th ee ons ar penn ithe xan is compo,
Beeonic pec (UV. vil and y petscopy a the recent nea deine he
ne fentes Becton spec pre br fora aout the energie fois stapes
Coplas (2, eter te compet i eel or ind acid or tea. Kay
peroo giveth formal the seu o compl, bond lens and Bod an
Meg mamen messenen et he ifomatan sot compas eft te compl
teeta or que plana o cbc, 5
Sig Concept of Corda Band
Acadie to Sigil’ concep e ods date ron pars 1 the mel cin or atom
celia te formato of ect hoben cala pds wich pr as
M «-L, Therefore, the complex ion, (Co(NH3)g]”* can be written as.
mal
Ha Ms
NU
wy | Nes
te
The donation of a lesen pi y Nsom of Ny bas been represent by tae The
coordinate Don is very aro coven bond
ations of Sigwick's Concept: The donation of one lern pr by ech ligt the
ental metal cation ato M Léon os case escalation afaegatveclagean
He central cl ai or atom, Du 0 soma of negative charge on he mel ction oro a
part one character etd he complexing ies le
According to Pauling's electronentrality principle, the metaltigznd bonds have some ionic
anse. T preven ihe accoulaton of eave charg on metal cation or lm, he bond ai
¿files mus be ace moe story dono so o the ligando or In ao he
Bord there should be mel and bonding
Effective Atomic Number (EAN) Rule: Te eve sonic number of meta caton or atom ina
comple i the sum of electons on mal ad the losen donated by the ligands. Acocng lo
Sig's re tie cr EAN} EAN fm qua si umber abet
inert gas ie, equal to 36 (KA, St (Xe) ar 86 (Rx), For example, EAN of {Co(NHs)g}™* can be
calculated as follows
Number ofelechons on Coatom=27 "
Number of electrons on Co jon = 27 ~3 = 24
[Number of electron donate y six NH ligands =2 x 6 12
EAN of Co™ in CofNH1s)g]* = 24 +12= 36
An altemate and moe general nl se 18 lctron rate. According oti ue, in a complex the
sam of valence eletons and the electrons donated by the ligands is 1, It provides a closed and sabe
configuration, ns? (=D! np“
or example: For [Co (NE) +
Valence shell econ oniguraon of Co =347 4?
‘Valence shell electronic configuration of Co™* =34% 45°
Number ofeecrons in valence heil ofCo™ = 6
Number of elecson donated by six NHy molecules = 2 6 = 12
‘Number of valence lctensin{Co(NHs)g}** =6+12 =180"
‘The complexes which fellow the EAN os 18 electron ule are considered to be subl. EAN and 1
electron rules are similar but the 18 leon rule is more advantageous because there is no ned 10)
remember the aomi numberof each noble gs. However, there are some exceptions which obey
neither EAN nor 18 eeiro rue, The complexes ia which the metal ations o atoms eve dd mu
of electrons never obey the EAN rule o 8 elec rule because the sum of toa lcrons or valenc
shell electrons andthe electrons dont by the ligand also an odd number For example consider the
complex Fe (CN)
For EAN Rale:
Number ofelectas on Fe atom = 26
Nurberof electron on Fe** ion = 23
‘Number of electri donated by sx CN ligands = 2 x 6= 12
EAN Ge (ONG) = 23 + 12 35
“Thus,(Fe(CNJ6]”” does not obey EAN rule.
For 18 Electron Rule:
‘Valence shell electronic configuration of Fe atom = 34° 45?
‘Valence shell electronic configuration of Fe** ion =34%
‘Number of lence een in Fe? ion
Number of eletondonsted by six CN ligands =2 x 6 = 12
Number of valence elesronsinfF{CN).¢]?- = $41
‘Thus, (Fe(CN} 4]? doesnot obey the 18 electron rule.
7
‘The complexes of d® metal having coordination number 4 also obey neither EAN rule nor 18
decron rule. For example, the complexes (NiCly]?, INi(CN)«], [PACK], (CUP obey
either the BAN le or 18 clecton nk.
‘The llstation of EAN and 18 lecuon rule is given in Table 14.
‘Table 1.4: Illustration of EAN and 18 Electron Rule for Various Complexes
tag
24412=36(K) Jo fovi2=18
p4412=36(K) |6 [6s12=18
f4412=86(Ra).\6 — COTES
2848=36¢) |10 — fto+s=i8
10 [26+10=36(K) [e
[2412 =36(k9)
+ fa
ech" 26 lr I
qna De I» he
mo pa js
apace 6 [a
au? mola |
wann ler + lis faxana faseaeso [io ftova=ta
* These complexes bey neither EAN rule nor 18 electron rule.
¿CLASSIFICATION OF LIGANDS,
Ligands can be clasiid as mooodentate or polydentate ligands (uz, idee, dentate...)
“depending on be number of ligand donor atoms that attach tothe metal on o atom.
41) Monodéntate Ligands: ligand which hares electron prof ingle donor tom with a metal
stom o ion called a monodentate ligand. The word monodentate comes fom the Greek; monos and
‘the Latin : dents, monos means one and dentis means toot, literally means one tooth. Therefore, it
means tat a monodentate ligand bites a metal cation or atom with one lone pair ofeloctons. In general,
the denticty ofa ligand is he number of pirs of electro shared with the metal atom or ion. Some
‘common monadetae ligands are shown below
Negative ligands
Foro chloro Be bromo
Liste OH hydro Las
OF perso HC byte
pi
CO“ acetato SOP sapito
SO} sulphato S” sulphido. "NE amido
NH imido NE pitido, NG azido.
5207 ost CNT cyano NOS nitato
NO} nivo (orte N} ONO nitro (ori 0)
SON” cyan (or icyanato- S)
NCS" islam (or hiocyanato - N}
080° Cm
“C105 cloro
[Neutral igands which are named us such :
CeHs)5P _ viphenylphasphine . - + (CaHls)s B-‚rietyl phosphine
Cata ETS CsHsN pyidine (y)
NED NE tyne CH3NHp methylamine
CH) NK dimelhylanine (CHy)3N trimetiylamin
(Col) As tipleaylaine CHCN methyl cyanide or aceteitile
CHNC mtyisocyanide CH3OCH dimetyl er
CzHHsOC¿H5 diethyl ether
NHOH ——hydcoxylanine
Na diirogen
decron rule. For example, the complexes (NiCly]?, INi(CN)«], [PACK], (CUP obey
either the BAN le or 18 clecton nk.
‘The llstation of EAN and 18 lecuon rule is given in Table 14.
‘Table 1.4: Illustration of EAN and 18 Electron Rule for Various Complexes
tag
24412=36(K) Jo fovi2=18
p4412=36(K) |6 [6s12=18
f4412=86(Ra).\6 — COTES
2848=36¢) |10 — fto+s=i8
10 [26+10=36(K) [e
[2412 =36(k9)
+ fa
ech" 26 lr I
qna De I» he
mo pa js
apace 6 [a
au? mola |
wann ler + lis faxana faseaeso [io ftova=ta
* These complexes bey neither EAN rule nor 18 electron rule.
¿CLASSIFICATION OF LIGANDS,
Ligands can be clasiid as mooodentate or polydentate ligands (uz, idee, dentate...)
“depending on be number of ligand donor atoms that attach tothe metal on o atom.
41) Monodéntate Ligands: ligand which hares electron prof ingle donor tom with a metal
stom o ion called a monodentate ligand. The word monodentate comes fom the Greek; monos and
‘the Latin : dents, monos means one and dentis means toot, literally means one tooth. Therefore, it
means tat a monodentate ligand bites a metal cation or atom with one lone pair ofeloctons. In general,
the denticty ofa ligand is he number of pirs of electro shared with the metal atom or ion. Some
‘common monadetae ligands are shown below
Negative ligands
Foro chloro Be bromo
Liste OH hydro Las
OF perso HC byte
pi
CO“ acetato SOP sapito
SO} sulphato S” sulphido. "NE amido
NH imido NE pitido, NG azido.
5207 ost CNT cyano NOS nitato
NO} nivo (orte N} ONO nitro (ori 0)
SON” cyan (or icyanato- S)
NCS" islam (or hiocyanato - N}
080° Cm
“C105 cloro
[Neutral igands which are named us such :
CeHs)5P _ viphenylphasphine . - + (CaHls)s B-‚rietyl phosphine
Cata ETS CsHsN pyidine (y)
NED NE tyne CH3NHp methylamine
CH) NK dimelhylanine (CHy)3N trimetiylamin
(Col) As tipleaylaine CHCN methyl cyanide or aceteitile
CHNC mtyisocyanide CH3OCH dimetyl er
CzHHsOC¿H5 diethyl ether
NHOH ——hydcoxylanine
Na diirogen
Bees EE
Neutra ligans which are given special name
© exo 0 am
NE; anmine NO iros ÁS
cs thocarboyl NS finiront
(@)Polydentate Ligands or Multidentate Ligands: Te ligands that bond to metal ction or atom
(hg electron pars present on more than one donor atoms are called multidentate or polydentate
Hands (many tothe ligands), Polydentateiganes form one or moe ring wth metal cation or atom.
Palette ligands are called chelating ligands (the word derived fom cele meaning claw) because
Interaction of two ar more electron pars toa metal ion resulting the formation of one or mare rings
including meta ion resembles the grasping ofan object by the claw of ab. Thepolydentate ligands in
general, frm five or si membered rings including metal ion, wich are called chelate rings ard the
omplees containing chelate rings are called cheats.
“The xtr stability of chelates as compared to similar ndochelates is called chelate effect
CLASSIFICATION OF POLYDENTATE LIGANDS
(1) Bidentate Ligands
‘These ligands have two donor atoms which can attach 10 a single eta ation or atom, A bidentate
ligand form one S-oró-membered ing with a metal ion or atom Some examples bidentate ligands are
given below
al oxalato (ox)
coo"
NHyCH;C00~ elyeinto (ely)
Cy C= N—07
1
+ Lily C= N— OH
imethylelyosimato(dng)"
GC C0 © Gi Cm CHC
N 1 Ñ
Ote © Ho
Fe in
at
che = cea
lí
o o
ya)”
A
NS
er
u
on
Shydrasyiquinoline
o
CH; — Clty
I 1
Nilo Ni
ls —CH—CHo
Ne hag
Shydeoxygtiotnato econ)
Troplonsto
tfileneinmin (eo)
prenne Gr)
or 12 diaminoprogane
trimetylencdiamine (m)
13 diaminopropane
butyenediamine (bn)
012,3 diamiropropane
isobutlenediamin (60)
bipyridine oc bipyrdyt Copy or bips}
Neutra ligans which are given special name
© exo 0 am
NE; anmine NO iros ÁS
cs thocarboyl NS finiront
(@)Polydentate Ligands or Multidentate Ligands: Te ligands that bond to metal ction or atom
(hg electron pars present on more than one donor atoms are called multidentate or polydentate
Hands (many tothe ligands), Polydentateiganes form one or moe ring wth metal cation or atom.
Palette ligands are called chelating ligands (the word derived fom cele meaning claw) because
Interaction of two ar more electron pars toa metal ion resulting the formation of one or mare rings
including meta ion resembles the grasping ofan object by the claw of ab. Thepolydentate ligands in
general, frm five or si membered rings including metal ion, wich are called chelate rings ard the
omplees containing chelate rings are called cheats.
“The xtr stability of chelates as compared to similar ndochelates is called chelate effect
CLASSIFICATION OF POLYDENTATE LIGANDS
(1) Bidentate Ligands
‘These ligands have two donor atoms which can attach 10 a single eta ation or atom, A bidentate
ligand form one S-oró-membered ing with a metal ion or atom Some examples bidentate ligands are
given below
al oxalato (ox)
coo"
NHyCH;C00~ elyeinto (ely)
Cy C= N—07
1
+ Lily C= N— OH
imethylelyosimato(dng)"
GC C0 © Gi Cm CHC
N 1 Ñ
Ote © Ho
Fe in
at
che = cea
lí
o o
ya)”
A
NS
er
u
on
Shydrasyiquinoline
o
CH; — Clty
I 1
Nilo Ni
ls —CH—CHo
Ne hag
Shydeoxygtiotnato econ)
Troplonsto
tfileneinmin (eo)
prenne Gr)
or 12 diaminoprogane
trimetylencdiamine (m)
13 diaminopropane
butyenediamine (bn)
012,3 diamiropropane
isobutlenediamin (60)
bipyridine oc bipyrdyt Copy or bips}
1, 10- phenanthroline
ar o-phenanthroline (0- phen or phen)
‘o- phenylene bisdimethylarsie (dias)
/
ofl, “oH,
Note: The ligands like CO?”, CCOO”, NO3,NO5, 802,50, Na — Ni, 02, ete
Jue evo donor atoms but in genera they ac monodensteignds. They form either four o tree
membered rings including meta cation or atom and thee will be repulsion between donor atoms and
their electron pais which causes the ing t e stained and hence unstable.
Stain
ono Su
AA
Fer mic gs wa
on
an
var
Tee ent
mau ad
"These ligaids may behave as bideotte ligands when the size of metal ‘cation is large like
lanthanoids. For example, NO3 betaves as bidentate ligand in (Ce(NO 4)? in which coordination
numer of Co is 12. —
(2) Tridentate Ligands
‘Some important examples of tridentate ligands are shown below +
iehylenetriamine (dien)
A
2,2,2"epyridine or tespyridy! (tery)
(3) Tetradentate Ligands
Some importan examples fran gn gen below
os
fe fe
, ie .
10) Sa triethylenetetraamine (trien)
wie
uo] o ip inane ee)
oe
He
CH20007
Gi NE-CHCOO- Nitioiacetato (TAY
CH3C00°
(4) Pentadentate Ligands
Important examples of petadentae ligands are given below :
city Ch —Ñ CH) — a, NH
oii serene (ees)
aan uen an
“Boca | a ccoo”
(a N Nat Te ethylenediaminetrinctato
£ NA
a CH2C007
ar o-phenanthroline (0- phen or phen)
‘o- phenylene bisdimethylarsie (dias)
/
ofl, “oH,
Note: The ligands like CO?”, CCOO”, NO3,NO5, 802,50, Na — Ni, 02, ete
Jue evo donor atoms but in genera they ac monodensteignds. They form either four o tree
membered rings including meta cation or atom and thee will be repulsion between donor atoms and
their electron pais which causes the ing t e stained and hence unstable.
Stain
ono Su
AA
Fer mic gs wa
on
an
var
Tee ent
mau ad
"These ligaids may behave as bideotte ligands when the size of metal ‘cation is large like
lanthanoids. For example, NO3 betaves as bidentate ligand in (Ce(NO 4)? in which coordination
numer of Co is 12. —
(2) Tridentate Ligands
‘Some important examples of tridentate ligands are shown below +
iehylenetriamine (dien)
A
2,2,2"epyridine or tespyridy! (tery)
(3) Tetradentate Ligands
Some importan examples fran gn gen below
os
fe fe
, ie .
10) Sa triethylenetetraamine (trien)
wie
uo] o ip inane ee)
oe
He
CH20007
Gi NE-CHCOO- Nitioiacetato (TAY
CH3C00°
(4) Pentadentate Ligands
Important examples of petadentae ligands are given below :
city Ch —Ñ CH) — a, NH
oii serene (ees)
aan uen an
“Boca | a ccoo”
(a N Nat Te ethylenediaminetrinctato
£ NA
a CH2C007
A
(6) Hexadentate Ligands
The most important example of ead ide:
Bocce Fe amd‘
> an am [
Re cæcoû
ethylenediamineteraacetato (ea or EDTA)
Since EDTAS bonds 10 a mea ion through six donor atoms, therefore, it forms highly sable
‘complexes and in general, is used to bold metal ions in solution. Me +
EDTA* ligand is used to trap metal ons such as Mg * and Ca?“ ions in hard water.
EDTA* is also wed to teat metal, pecially lead poisoning. Six donor atoms of EDTA bond to
6° ion to form very stable complex ion (Figure 1.9) which is removed from the blood ard issues and
excerted from the body with the hep of kidneys as soluble chelate [Pb (DTA.
co.
a, A
ot 1
(Wigan EDTA game of:
. D GANDS N“
The monodenté inde wich bave to or mor dierent door aoms cn rite am
cation trough either ofthe vo dies, Te gas ae called ambiente de When 2
bid rd onda he mel nn ough eher of th te door som wort
Compounds se oline whic ae cal ings somes Examples of biene ido
SON NOR ~S,0F CON, SO? .(I)aCO, (NF) CS ad (CH) 80. Pur pt
NO}, SCN" 2085501” none ofthese hs produced nage mes. NOS land, rename
fi cordate 103 meeting her N00 slam as shown in Figure 146
a
N,
Den
ra
Slee WL yO alcoi metal
Simitarly, SCN can coordinate with metal cation either through S or N atom as shown below :
Mescn~ MeNcs~
Sato of SCN N atom of SCN
‘coordinated to metal ion coordinated to metal ion
‘The ligands in which one or two different donor atoms have aleast two pais of electrons and share
these electron pairs with two metal vns atoms (one pair with one atom or on) simultaneously are
called bridging ligands. The interaction ofbridping ligands with metal ions orators can be cepreseated
SMeILIOM
‘The monodentate ligands having two lon par of electrons on one donor atom which acts bridging
17,0 ete. The monodentateligands having no lone
cr,
ligands ar 8H
pairs on two different atoms (one pron one atom) are ¿SCN”Z, ¿COZ, tN, NHi— Ni,
N03,0% 05 50% 50 05, pri an ci
‘The bridging ligands in which each ofthe two diferent donor atoms has atleast evo pais of
electrons like SCN, ether one or bth dor atom ofthe ligands can coordinate to 0 dierent metal
atoms or ions.
‘A bridging ligands forms twoa-boods with two metal ons or atoms (onec- bond with one meta ion
or atom} and these complexes re called bridging complexes or multinuclear or polynuclear complexes
Ifa bridging ligand contain (wo different donor atoms with ane lone pair of elecron on each, hea
‘one donor atom is coordinated to one metal and the other donor atom tothe other metal.
For example =
Mean tM, and [Es 0—0- Cathy)
«ance alé
FUEXIDENTATELIGANDS —
Tie side re orate, Th nd cin ii
tl ui ng cetera onde ae
A anal ip age copia
0},SOF,SO NO5,N2,0n,N NH, ee. When these ligands behave as nme
(6) Hexadentate Ligands
The most important example of ead ide:
Bocce Fe amd‘
> an am [
Re cæcoû
ethylenediamineteraacetato (ea or EDTA)
Since EDTAS bonds 10 a mea ion through six donor atoms, therefore, it forms highly sable
‘complexes and in general, is used to bold metal ions in solution. Me +
EDTA* ligand is used to trap metal ons such as Mg * and Ca?“ ions in hard water.
EDTA* is also wed to teat metal, pecially lead poisoning. Six donor atoms of EDTA bond to
6° ion to form very stable complex ion (Figure 1.9) which is removed from the blood ard issues and
excerted from the body with the hep of kidneys as soluble chelate [Pb (DTA.
co.
a, A
ot 1
(Wigan EDTA game of:
. D GANDS N“
The monodenté inde wich bave to or mor dierent door aoms cn rite am
cation trough either ofthe vo dies, Te gas ae called ambiente de When 2
bid rd onda he mel nn ough eher of th te door som wort
Compounds se oline whic ae cal ings somes Examples of biene ido
SON NOR ~S,0F CON, SO? .(I)aCO, (NF) CS ad (CH) 80. Pur pt
NO}, SCN" 2085501” none ofthese hs produced nage mes. NOS land, rename
fi cordate 103 meeting her N00 slam as shown in Figure 146
a
N,
Den
ra
Slee WL yO alcoi metal
Simitarly, SCN can coordinate with metal cation either through S or N atom as shown below :
Mescn~ MeNcs~
Sato of SCN N atom of SCN
‘coordinated to metal ion coordinated to metal ion
‘The ligands in which one or two different donor atoms have aleast two pais of electrons and share
these electron pairs with two metal vns atoms (one pair with one atom or on) simultaneously are
called bridging ligands. The interaction ofbridping ligands with metal ions orators can be cepreseated
SMeILIOM
‘The monodentate ligands having two lon par of electrons on one donor atom which acts bridging
17,0 ete. The monodentateligands having no lone
cr,
ligands ar 8H
pairs on two different atoms (one pron one atom) are ¿SCN”Z, ¿COZ, tN, NHi— Ni,
N03,0% 05 50% 50 05, pri an ci
‘The bridging ligands in which each ofthe two diferent donor atoms has atleast evo pais of
electrons like SCN, ether one or bth dor atom ofthe ligands can coordinate to 0 dierent metal
atoms or ions.
‘A bridging ligands forms twoa-boods with two metal ons or atoms (onec- bond with one meta ion
or atom} and these complexes re called bridging complexes or multinuclear or polynuclear complexes
Ifa bridging ligand contain (wo different donor atoms with ane lone pair of elecron on each, hea
‘one donor atom is coordinated to one metal and the other donor atom tothe other metal.
For example =
Mean tM, and [Es 0—0- Cathy)
«ance alé
FUEXIDENTATELIGANDS —
Tie side re orate, Th nd cin ii
tl ui ng cetera onde ae
A anal ip age copia
0},SOF,SO NO5,N2,0n,N NH, ee. When these ligands behave as nme
«he complexes so formed are really stable. But when these ligands behave as bidentate ligands,
Stan oe
Ha A,
M
A ny AN
e Three membered ring Four membered ring
Ingerenl, the cheats having re or four membered rings ae untble because of tester sta,
However, exceptionally thee are some stable chelates having four membered rings like[Ce(NOs )é
{0x100s)5}" es EDTA isa hxadentae gad, but sometime ac a ptet or dna
| Tun depeding upon ke size and sterochemsty ofthe chelate formed, Fr example, a complexes
Eee and [COBHMEDTA)]”, EDTA acts es pentadenate ligand and in complex
[PAGIEDTAJ?, it cs os etradeatate ligand and in complexes (CaEDTA) or [MG(EDTA)Í it
acts as header
SYMMETRICAL AND UNSYMMETRICAL BIDENTATE LIGANDS
‘The bidentate ligands in which both the donor atoms are sam, recalled symmetrical bidentate
ligands and the ligands in which both the donor atoms ae diffrent are called unsymmetrical bidentate
ligands, The symmetical and asymmetrical bidentate ligands ae represented as (AA) and (AB)
respectively where A and B are donor atoms. Examples of symmetical ad unsymmetrical ligands are
given below
ne Ugands FETE PU mme ad
cn HAN CH, 0007
La As lycra, gy
ue
NB NB
butlenediamins, bn
oreo
0-00
rola, ox
nie naptolioa
N= aN
À d=
‘opbenanthrone phen
ih CCC CH;
1 n
o 6
aceaceonat, cas”
Te ri of eye deat ligands sal eatin ca be epee by neue
AD vtr Li ario of mme int gd ed to A's two iia don
toms The atashmeat of symmeircal bidntte De, ethylenediamine,
NB — CH — Cha — NH, for example, to Co™ ion in (One) ins shown in Figure 17.
CRE
8
|
que
ad
POD, | = KD
E Bi
tl
PA A NUE Coton.
Similaly, theatachment of oxalato, C202" ligand to Fe?” ion is shown in Figure 1.8.
>
2 yy
e e
A]
A oe
GEL Arceo of COP and eos
Stan oe
Ha A,
M
A ny AN
e Three membered ring Four membered ring
Ingerenl, the cheats having re or four membered rings ae untble because of tester sta,
However, exceptionally thee are some stable chelates having four membered rings like[Ce(NOs )é
{0x100s)5}" es EDTA isa hxadentae gad, but sometime ac a ptet or dna
| Tun depeding upon ke size and sterochemsty ofthe chelate formed, Fr example, a complexes
Eee and [COBHMEDTA)]”, EDTA acts es pentadenate ligand and in complex
[PAGIEDTAJ?, it cs os etradeatate ligand and in complexes (CaEDTA) or [MG(EDTA)Í it
acts as header
SYMMETRICAL AND UNSYMMETRICAL BIDENTATE LIGANDS
‘The bidentate ligands in which both the donor atoms are sam, recalled symmetrical bidentate
ligands and the ligands in which both the donor atoms ae diffrent are called unsymmetrical bidentate
ligands, The symmetical and asymmetrical bidentate ligands ae represented as (AA) and (AB)
respectively where A and B are donor atoms. Examples of symmetical ad unsymmetrical ligands are
given below
ne Ugands FETE PU mme ad
cn HAN CH, 0007
La As lycra, gy
ue
NB NB
butlenediamins, bn
oreo
0-00
rola, ox
nie naptolioa
N= aN
À d=
‘opbenanthrone phen
ih CCC CH;
1 n
o 6
aceaceonat, cas”
Te ri of eye deat ligands sal eatin ca be epee by neue
AD vtr Li ario of mme int gd ed to A's two iia don
toms The atashmeat of symmeircal bidntte De, ethylenediamine,
NB — CH — Cha — NH, for example, to Co™ ion in (One) ins shown in Figure 17.
CRE
8
|
que
ad
POD, | = KD
E Bi
tl
PA A NUE Coton.
Similaly, theatachment of oxalato, C202" ligand to Fe?” ion is shown in Figure 1.8.
>
2 yy
e e
A]
A oe
GEL Arceo of COP and eos
‘The anachmeat ofan unsymmetrical bidentate ligand, AB tothe mat eatin can be shown by a
curve ML, whee Liste sbreviton othe ganda an Bar od ono tons.
“Theattachment of unsymmetrical bidentate ligand für example, glcinato, NHyCH 2000” toCo**
on is shown in Figure 1.9
1
¿mo ne
œ—0
/ DI on to Lx
ral,
ES y
Ne
o
i
5
MAGROCYCLICAIGANDS
cou eget gs iat a mel tl oF eo pt
Ten coin ever door om Inside ei gode
Please mal eon For carl. co,
‘elon ad an D sl neta alent euch
En
"macul ipa fom mee sabe maso ones
comparado comple med by the nmeyek chelating ds
geule nd pect door om a tol ml
lise Tift called macros has bon ved
athena gand form mare able comes ts lps
‘monodentate ligands and the chelates of higher denticity (ie, CN.)
tte mom slo than the ches of Tower en. Abo,
macrocyclic ligands of appropriate size form more stable
completes tante chelating pnd These llore
(omnia 0
IHOMOLEPTIC AND.HETEROLEPTIC COMPLEXES
Complexes in which a metal is bound to only one kind of donar group, eg, (Co(NH )¢)?* are
kan mol complete tn te ample ou o or a as na
‘donor groups, eg. [Co(NH)4C12 ]* are known as heteroleptic complexes.
Gb dde QS iad eae A ay
Anus cie
BEE IE ion Coude ee)
1. NO; isan Eliana, be
2. Diethylenetriamine is a ligand, > Dd
3. Coordination number of Mo in[MO(CX)gT” is
4. The oxidation aumber of Fe in (Fe(H0)s (NO) is... PES
5. Inthe complex Co(en); J* en is
12. Biylenediamine is 2
13. Gly QUÍZOHACOO” is an aa well a. ind,
14. Thecomplex(Cofen)s}** isa sÿpe of a
1S, Te magaiude of depression in freezing pont of m aguas schon o (Co(NE CHC
han ha of Im agueous of sation of Ca(NHs CJL
16. The primary and secondary valecis in [CONS ) CO a do and
respectively }
17. Treeomplex[FCNG]" u... "18 electron le, u
18. The complex (CON 167 2." EAN rule.
(ans. 1. ambidentae 2. went orchelting
38 a+
5, bidentate 6. bidenate
7. ambidectate, ambidentae 8, macro
9. monodentate, bridging, 10, headenate (chelating)
1. geater 12. symmeti identae
15. unsymameti, bidentate 14, chloe
15. gener 16.3,6
17. does not obey 18. obey
curve ML, whee Liste sbreviton othe ganda an Bar od ono tons.
“Theattachment of unsymmetrical bidentate ligand für example, glcinato, NHyCH 2000” toCo**
on is shown in Figure 1.9
1
¿mo ne
œ—0
/ DI on to Lx
ral,
ES y
Ne
o
i
5
MAGROCYCLICAIGANDS
cou eget gs iat a mel tl oF eo pt
Ten coin ever door om Inside ei gode
Please mal eon For carl. co,
‘elon ad an D sl neta alent euch
En
"macul ipa fom mee sabe maso ones
comparado comple med by the nmeyek chelating ds
geule nd pect door om a tol ml
lise Tift called macros has bon ved
athena gand form mare able comes ts lps
‘monodentate ligands and the chelates of higher denticity (ie, CN.)
tte mom slo than the ches of Tower en. Abo,
macrocyclic ligands of appropriate size form more stable
completes tante chelating pnd These llore
(omnia 0
IHOMOLEPTIC AND.HETEROLEPTIC COMPLEXES
Complexes in which a metal is bound to only one kind of donar group, eg, (Co(NH )¢)?* are
kan mol complete tn te ample ou o or a as na
‘donor groups, eg. [Co(NH)4C12 ]* are known as heteroleptic complexes.
Gb dde QS iad eae A ay
Anus cie
BEE IE ion Coude ee)
1. NO; isan Eliana, be
2. Diethylenetriamine is a ligand, > Dd
3. Coordination number of Mo in[MO(CX)gT” is
4. The oxidation aumber of Fe in (Fe(H0)s (NO) is... PES
5. Inthe complex Co(en); J* en is
12. Biylenediamine is 2
13. Gly QUÍZOHACOO” is an aa well a. ind,
14. Thecomplex(Cofen)s}** isa sÿpe of a
1S, Te magaiude of depression in freezing pont of m aguas schon o (Co(NE CHC
han ha of Im agueous of sation of Ca(NHs CJL
16. The primary and secondary valecis in [CONS ) CO a do and
respectively }
17. Treeomplex[FCNG]" u... "18 electron le, u
18. The complex (CON 167 2." EAN rule.
(ans. 1. ambidentae 2. went orchelting
38 a+
5, bidentate 6. bidenate
7. ambidectate, ambidentae 8, macro
9. monodentate, bridging, 10, headenate (chelating)
1. geater 12. symmeti identae
15. unsymameti, bidentate 14, chloe
15. gener 16.3,6
17. does not obey 18. obey
1. Which ofthe following ligands does nt bebave as
(Noy ao” . Lg 19. se 46 se o 20
CET 05
Which ofthe following ligando bles a a ambidenae igen?
Ka) NOs “so
(950, (9007 wee | 1 How many col ings ren lin compen?
3. The oxidation state of Rh in (Ny) (RAI) is ae ee.
a pes ISCH:
Chilo 1053 © [Cofdien2}**
Which ofthe following ligands beahves as a exidentate ligand? KO [Cá(iieny o
ano Oe ger OIRCIS-cown-67
(a wor ur 2. What is the expected rezing poi depresion of 0.01 m COQ «Cl complex?
5. Oxidation number of W in MEWOy is: wh (Ky =-186"Chn)
@2 ws ot 3. Arrange the following complexes in the increasing order of
ox CT RARES (a) conductivity in aqueous soon.
6. A ligand in men compleres behaves as (©) depression in freezing pin considering 01 m concentration ofeach complex.
(@ election pr donor leiste je ICONE CL CL (CON )sCICH, (CO(NH Je Pls
Gi) mucophile (elec 4. A Qs, 1-) electri comple is expected to have higher molar conductivity an (1, 1)
Wand Gi) only leva complex. Explain
(0) @ and (ii) only 5. A solution is made by dissolving 0.875 y of CoQNH «Cl; in 25.0 g of water which freezes at
@ O, Gana ip only / 0 56°C. Suggest he sucre of his compound. Calcula number of mole of ies produced
(@)Allofthe above when one male o£Co(Ni Ch is dissolved in wae.
ligand that exkibis linkage isomerism init transition metal complexes is 6. Define the
SÍ GO LT Te # Papers
EE ) Ligan
©) NOsT rc (c) Ambidentate ligands
ich ofthefollowingisnotacheaingligmd? * (@) Chelating ligas
(a) Thiosulphato (b) Oxalato. (e) Flexidentate ligands
(©) Giycinato A) Eihylenediamine (0 Bridging ligands
3. A compound contains 1.08 mol of Xa, 039 mol ofCu and 2.16 mol of. ls aqueous solution (@)Doner atom
shows osmotic pressure which is the times at of rca having srt molar concentration, The (0) Macrocyaioigands
formula ofthe compounds (Coordination number
(0) Nagle) ONCE) 4 6 Counter ion
(© fur) ar Complex ion
» Re
(Noy ao” . Lg 19. se 46 se o 20
CET 05
Which ofthe following ligando bles a a ambidenae igen?
Ka) NOs “so
(950, (9007 wee | 1 How many col ings ren lin compen?
3. The oxidation state of Rh in (Ny) (RAI) is ae ee.
a pes ISCH:
Chilo 1053 © [Cofdien2}**
Which ofthe following ligands beahves as a exidentate ligand? KO [Cá(iieny o
ano Oe ger OIRCIS-cown-67
(a wor ur 2. What is the expected rezing poi depresion of 0.01 m COQ «Cl complex?
5. Oxidation number of W in MEWOy is: wh (Ky =-186"Chn)
@2 ws ot 3. Arrange the following complexes in the increasing order of
ox CT RARES (a) conductivity in aqueous soon.
6. A ligand in men compleres behaves as (©) depression in freezing pin considering 01 m concentration ofeach complex.
(@ election pr donor leiste je ICONE CL CL (CON )sCICH, (CO(NH Je Pls
Gi) mucophile (elec 4. A Qs, 1-) electri comple is expected to have higher molar conductivity an (1, 1)
Wand Gi) only leva complex. Explain
(0) @ and (ii) only 5. A solution is made by dissolving 0.875 y of CoQNH «Cl; in 25.0 g of water which freezes at
@ O, Gana ip only / 0 56°C. Suggest he sucre of his compound. Calcula number of mole of ies produced
(@)Allofthe above when one male o£Co(Ni Ch is dissolved in wae.
ligand that exkibis linkage isomerism init transition metal complexes is 6. Define the
SÍ GO LT Te # Papers
EE ) Ligan
©) NOsT rc (c) Ambidentate ligands
ich ofthefollowingisnotacheaingligmd? * (@) Chelating ligas
(a) Thiosulphato (b) Oxalato. (e) Flexidentate ligands
(©) Giycinato A) Eihylenediamine (0 Bridging ligands
3. A compound contains 1.08 mol of Xa, 039 mol ofCu and 2.16 mol of. ls aqueous solution (@)Doner atom
shows osmotic pressure which is the times at of rca having srt molar concentration, The (0) Macrocyaioigands
formula ofthe compounds (Coordination number
(0) Nagle) ONCE) 4 6 Counter ion
(© fur) ar Complex ion
» Re
of the following compounds?
7. Whats the coordination number ofthe meal in each
() (Cofen)s ß
(cai)
CI
CMOS)
(e) Na2[FeCAOs (NO)
@ (Cafes
WERD],
Coordination number of mtn ints complexes isthe number of door ms sisted 1
Q0u Coordination number and geometry of the complexes are related to one another. For example,
complexes with coordination number 4 ae eter terahedra or square planar and he complexes With
coordination number 6 ae oetakedal. The coordination number and geometry ofthe complexes depead
upon he flowing Gets
1. The sie of metal ion alce
2. Size ofthe ligands and te steric inerasin between the ligands.
3. Electronic interactions and th amber of electrons in metal ion cr atom.
“4 Whether the pan frm m bors with mel on o at
In general, he metal los o ons of ages size (say dd: and Sd: serie wanton metal and
anthanoids) favour the formation of complexes higher coordination nunbes because serie repalsion
(decrease with iczese in size of cena metal cation For similar reasons, bulky ie ofen fora
‘complexes of low coordination numbers and the smaller size ligands form complexes of higher
‘coordination number. Complexesofhighercoodinaton nus ar formed Fr HEA ation
de = craton of 4. sud Sd anton elements which Lie on the left of the period and basa few mur of @-
© _electrons. The metal cation or atom having a small number of d- electrons can accept more electron pairs
‘rom the ligands, one example is{Mo(CN)s On the other hand, the metal cations which ies onthe
Fight ofthe period and ar ich in + ten form complexes of low coordination numbers À few
‘examples are (PtClz}?*[PACIgP”[AgCl2]” etc. These atoms or ions can accept less number of
lens fom the ligands. Complexes of low coordination numbers ar alo fanned when ie igands
formed multiple bonds wit metal ain, such as M03, C102", (CO) et, The mat of
multiple bonds between meta cation and ligands oppose Ihe addition of more number of ligands
The coordination number of metal ons rnges fom 1, a5 in on pairs uch as Na CI” inthe geneous
state to 12 as in[CA(NO3)]” ion. In general, the coordination number of metals in complexes ate
found to be 2 to 9, out of wich coordination umber 2, 4 and 6 are most common.
7. Whats the coordination number ofthe meal in each
() (Cofen)s ß
(cai)
CI
CMOS)
(e) Na2[FeCAOs (NO)
@ (Cafes
WERD],
Coordination number of mtn ints complexes isthe number of door ms sisted 1
Q0u Coordination number and geometry of the complexes are related to one another. For example,
complexes with coordination number 4 ae eter terahedra or square planar and he complexes With
coordination number 6 ae oetakedal. The coordination number and geometry ofthe complexes depead
upon he flowing Gets
1. The sie of metal ion alce
2. Size ofthe ligands and te steric inerasin between the ligands.
3. Electronic interactions and th amber of electrons in metal ion cr atom.
“4 Whether the pan frm m bors with mel on o at
In general, he metal los o ons of ages size (say dd: and Sd: serie wanton metal and
anthanoids) favour the formation of complexes higher coordination nunbes because serie repalsion
(decrease with iczese in size of cena metal cation For similar reasons, bulky ie ofen fora
‘complexes of low coordination numbers and the smaller size ligands form complexes of higher
‘coordination number. Complexesofhighercoodinaton nus ar formed Fr HEA ation
de = craton of 4. sud Sd anton elements which Lie on the left of the period and basa few mur of @-
© _electrons. The metal cation or atom having a small number of d- electrons can accept more electron pairs
‘rom the ligands, one example is{Mo(CN)s On the other hand, the metal cations which ies onthe
Fight ofthe period and ar ich in + ten form complexes of low coordination numbers À few
‘examples are (PtClz}?*[PACIgP”[AgCl2]” etc. These atoms or ions can accept less number of
lens fom the ligands. Complexes of low coordination numbers ar alo fanned when ie igands
formed multiple bonds wit metal ain, such as M03, C102", (CO) et, The mat of
multiple bonds between meta cation and ligands oppose Ihe addition of more number of ligands
The coordination number of metal ons rnges fom 1, a5 in on pairs uch as Na CI” inthe geneous
state to 12 as in[CA(NO3)]” ion. In general, the coordination number of metals in complexes ate
found to be 2 to 9, out of wich coordination umber 2, 4 and 6 are most common.
Coordination Number 2
A fer number Of complexes are known with continaon number 2. The complexes with
tionnumber2are given by Cu”, Ag", Au” and Hg? ons Ge, species) These complenes
Have liner geometry. Some example re
QT CRT (OMC)? [AGNES )2I, (ARCA? (AECI, [auc],
LAN [CNO HICH 2}, [AM(PR)2J” ec. These complees are typically unstable
towards th frtheradton aflignds 1 form complexes of high coordination umber oran as
LUNA +20N" —+ (ON)
[AONE )2 1" + 2NB3— ANNE)
THRON)? + CN" [Hg(cr) 4
The cyano complexes Ag * and Au” with coordination number 2 ae cs sabe as they exist as
erh an) complexes. Te solid K[Cu(CN) contains a can Ike tte in
which oonfnatn ner ofc} ae eel
‘The complexes of coord y also formed by the sterically
nation nu Io fo iy hindered (i.e,
tias such as INSPbs)2 1, [N(SiMes 21", IN(SIMEPh2)2]” de vih the metal ions ce
Ma?*,5e%,Co% and Ni?*. One important example is Pe[N(SIPh)2 .
Coordination Number 3
‘This coordination number is are in complexes and th nati
lexes and the geometies comesponding to coordination
fumber 3 ae tigoal planar and trigonal pyramids. Some famous examples ae KÍCACN (See
Figure 2.1), Coy, infinito single chain, He; and the pyramidal Ct, (Figure 22).
Suc) +0 su CT
Tt
AA
Coordination Number 4
‘Thisis seco nt important coordination number in sordinsionchanisıy ater coordination
umber 6 which to be discussed later. The geometry comespondin tthe conaton number 4 is
tea: square pa,
Tetbedolcomplers are favoured when the ligand are larger ike CT, Br I” and to coral
metal cation or stom is smaller with : (i) 4% and dP-configurations and (i) d*-configurations where
square planar or octahedral is not favoured by number of d- electrons, such as Fe**(45), Co?* (d?),
Ni*(a®),Cu?*(@? ions which form tetrahedral complexes with C1”, Br” ions.
‘The excatoss of tanstion meals in high oxidaon states ac, gencally,terabedral such as
VO} CO? Ma de. A
Square plana mplves are Less favoured sterically han erahedal complexes. Therefore, these
are prohibitively crowded by large ligands. Co?" (347), Ni?" (34°) and Ca” (24?) fon square planar
complexes with srepir ligands such as CN”. The metal ions belonging do dd: and Sd: eres
transition elements such as Rh",In*, Pd?*, Pt?*, Au?" form invariably square planar complexes
regardless ofthe adonor or r-acceptor character of the ligands, Examples of square planar complexes
are : NO] (CAC) LCACN) 4 P (CUVE Da À", (PECL PCIe, TALCA,
(RO PCI {COV SP) aC et.
‘Coordination Number 5
“The complexes of coordination number 5 are less common than tat of eoonfinaion 4 and 6 fr de
block clement, The complexes corresponding to coordination number S ae ether square pyramidal
A fer number Of complexes are known with continaon number 2. The complexes with
tionnumber2are given by Cu”, Ag", Au” and Hg? ons Ge, species) These complenes
Have liner geometry. Some example re
QT CRT (OMC)? [AGNES )2I, (ARCA? (AECI, [auc],
LAN [CNO HICH 2}, [AM(PR)2J” ec. These complees are typically unstable
towards th frtheradton aflignds 1 form complexes of high coordination umber oran as
LUNA +20N" —+ (ON)
[AONE )2 1" + 2NB3— ANNE)
THRON)? + CN" [Hg(cr) 4
The cyano complexes Ag * and Au” with coordination number 2 ae cs sabe as they exist as
erh an) complexes. Te solid K[Cu(CN) contains a can Ike tte in
which oonfnatn ner ofc} ae eel
‘The complexes of coord y also formed by the sterically
nation nu Io fo iy hindered (i.e,
tias such as INSPbs)2 1, [N(SiMes 21", IN(SIMEPh2)2]” de vih the metal ions ce
Ma?*,5e%,Co% and Ni?*. One important example is Pe[N(SIPh)2 .
Coordination Number 3
‘This coordination number is are in complexes and th nati
lexes and the geometies comesponding to coordination
fumber 3 ae tigoal planar and trigonal pyramids. Some famous examples ae KÍCACN (See
Figure 2.1), Coy, infinito single chain, He; and the pyramidal Ct, (Figure 22).
Suc) +0 su CT
Tt
AA
Coordination Number 4
‘Thisis seco nt important coordination number in sordinsionchanisıy ater coordination
umber 6 which to be discussed later. The geometry comespondin tthe conaton number 4 is
tea: square pa,
Tetbedolcomplers are favoured when the ligand are larger ike CT, Br I” and to coral
metal cation or stom is smaller with : (i) 4% and dP-configurations and (i) d*-configurations where
square planar or octahedral is not favoured by number of d- electrons, such as Fe**(45), Co?* (d?),
Ni*(a®),Cu?*(@? ions which form tetrahedral complexes with C1”, Br” ions.
‘The excatoss of tanstion meals in high oxidaon states ac, gencally,terabedral such as
VO} CO? Ma de. A
Square plana mplves are Less favoured sterically han erahedal complexes. Therefore, these
are prohibitively crowded by large ligands. Co?" (347), Ni?" (34°) and Ca” (24?) fon square planar
complexes with srepir ligands such as CN”. The metal ions belonging do dd: and Sd: eres
transition elements such as Rh",In*, Pd?*, Pt?*, Au?" form invariably square planar complexes
regardless ofthe adonor or r-acceptor character of the ligands, Examples of square planar complexes
are : NO] (CAC) LCACN) 4 P (CUVE Da À", (PECL PCIe, TALCA,
(RO PCI {COV SP) aC et.
‘Coordination Number 5
“The complexes of coordination number 5 are less common than tat of eoonfinaion 4 and 6 fr de
block clement, The complexes corresponding to coordination number S ae ether square pyramidal
{(GP)octigonal bipyramidal (TBP). However, both ese eomatries undergo some distortion tom theie
ideal geometries. These two geomerrie can be inecontetd by small change in bond angles because
thes vo geonetssofen di itl ia energy fom one aster. Moteros and Quggenberser has
produced a series of coordination compounds of coordination abe 1 <how a sharp anion ofa
‘ideal trigonal bipyramidal to square pyramidal.
ICH", [PICSHS)S1,ICOCCSHTNO) ST" INCH", INHNCSHia)s}, [Sb(CeHs)s
Sure prams
St
Tet
In some cases it has been observed tht he ponte gangs or macrocyclic ligands favour the
square pyramidal geometry. For example, the ion atom in dens ai a
oral coadiaron (Figure 2.4)
The [NI(CN)s }°” ion can exist as both square pyramidal [Figure 2.5a)} and trigonal bi ai
Peones ON
-
al fo]
cx cu
Sad CEE
no Non ar
Jn general, goal Bpsramial wit monodenat ins ae highly Nina in soliton, ie. a
Nod it cual ne mom cms ns mc Mang ha
ligands may occur by Berry pseudorotation (Figure 2.6) o
:
z 4 co
& yA
lo
Shemogloin and myoplobin has ww
|
vu
Serien
FCO) complex, for example, is int ipyramia in cta, however, in solution he
al nd qua ign exchange rt sch dt elias can no be distinguished by NM
‘which basatimescale=10°3s, and the °C NMR spectrum of PACO); show's nance, This
inde thatthe exchange fail and uteri ids aes place at aa thes fast on NMR scl.
A observed thatthe exchange ofthese ligands low on IR tine scale
Coordination Number 6
This isthe mest common and coomously importen coocivation number for transition metal
‘complexes. The possible geometries eoresponding to condition number 6 may be hexagonal plant
vigona! prismatic, octahedralortetagonai ito octal. Ina regular octahedral complex alike
ML bond distances ace equal and te complexes hve plane as wells centre of symmetries. note
Words, we can ey ha he regular octahedral complexes ac highly symmetric and have Oh symmeiy
Examples of some regular octahedral complexes ae : Completes of Crit) like
1CHEO)6]* CHC) complexes of Coi) ke [Co(1¿O)6]”*,ICH(NE Ye)” CHEN)",
complexes of Fe like [Fe{CN)6}*", complexes of NÉ like [NIQNH )6]°* ete. The structure of
‘regular octahedral comple, sty ML is shown in Figure 27.
‘Whe diferent kind of ligands are present in a che complex, the symmetry of the 1
clon can nat be reine
There ae some complexes of coordination number 6 which have all he sx ligands same
undergo some sor o distortion due to he electronic cet, The fist she tragoal distortion, eke
elongation o compression along one of te fared mail axe ofthe étre Figure 28), Ths
‘ype of diortion hasbeen discussed in JatrTelr irn or aa Tele effect
:
|
j
t
à o
Ps ee
ideal geometries. These two geomerrie can be inecontetd by small change in bond angles because
thes vo geonetssofen di itl ia energy fom one aster. Moteros and Quggenberser has
produced a series of coordination compounds of coordination abe 1 <how a sharp anion ofa
‘ideal trigonal bipyramidal to square pyramidal.
ICH", [PICSHS)S1,ICOCCSHTNO) ST" INCH", INHNCSHia)s}, [Sb(CeHs)s
Sure prams
St
Tet
In some cases it has been observed tht he ponte gangs or macrocyclic ligands favour the
square pyramidal geometry. For example, the ion atom in dens ai a
oral coadiaron (Figure 2.4)
The [NI(CN)s }°” ion can exist as both square pyramidal [Figure 2.5a)} and trigonal bi ai
Peones ON
-
al fo]
cx cu
Sad CEE
no Non ar
Jn general, goal Bpsramial wit monodenat ins ae highly Nina in soliton, ie. a
Nod it cual ne mom cms ns mc Mang ha
ligands may occur by Berry pseudorotation (Figure 2.6) o
:
z 4 co
& yA
lo
Shemogloin and myoplobin has ww
|
vu
Serien
FCO) complex, for example, is int ipyramia in cta, however, in solution he
al nd qua ign exchange rt sch dt elias can no be distinguished by NM
‘which basatimescale=10°3s, and the °C NMR spectrum of PACO); show's nance, This
inde thatthe exchange fail and uteri ids aes place at aa thes fast on NMR scl.
A observed thatthe exchange ofthese ligands low on IR tine scale
Coordination Number 6
This isthe mest common and coomously importen coocivation number for transition metal
‘complexes. The possible geometries eoresponding to condition number 6 may be hexagonal plant
vigona! prismatic, octahedralortetagonai ito octal. Ina regular octahedral complex alike
ML bond distances ace equal and te complexes hve plane as wells centre of symmetries. note
Words, we can ey ha he regular octahedral complexes ac highly symmetric and have Oh symmeiy
Examples of some regular octahedral complexes ae : Completes of Crit) like
1CHEO)6]* CHC) complexes of Coi) ke [Co(1¿O)6]”*,ICH(NE Ye)” CHEN)",
complexes of Fe like [Fe{CN)6}*", complexes of NÉ like [NIQNH )6]°* ete. The structure of
‘regular octahedral comple, sty ML is shown in Figure 27.
‘Whe diferent kind of ligands are present in a che complex, the symmetry of the 1
clon can nat be reine
There ae some complexes of coordination number 6 which have all he sx ligands same
undergo some sor o distortion due to he electronic cet, The fist she tragoal distortion, eke
elongation o compression along one of te fared mail axe ofthe étre Figure 28), Ths
‘ype of diortion hasbeen discussed in JatrTelr irn or aa Tele effect
:
|
j
t
à o
Ps ee
ES ERR ER SA
Éd
An anote o of stint ng rampes, eld gon! dri age
LU our treo oon es host ve pu rough le he tees
29) ing ina gona amp
ithe ligands ofa regular octahedra complex lik [Co(NE 61 replaced by chelating ligands like
-sttylenediamine, Ny —CHly —CHlp —Nip 0 form [Cofen); +, the of the regla
cerca Oh wD; brat ane NY
‘The complexes having trigonal prismatic geomet (Figure 2,10 re rar, but have been ford in
ysul latices of sulphides of heavy mets, for example, MoS; and WS», Tegoral primas.
complexes of d° configuration sch as (Z(CHsJ "and (W(CHs)] have alto been lola The
tigonal prismatic structure of{Re(S;C2Phz)s Js shown in Figure 2.10
Higher Coordination Numbers
‘Coordination number 7 isnot common. However, its encountered for a few 3d: and some dd: and
‘sd- metal complexes, where the larger central metal ion can accommodate mote than six ligands. The
geometries corresponding 10 the coordination number 7 are pentagonal bipyramidal, a capped
‘octahedcon and a capped trigona! prism (These three geometries are shown in Figure 2.11). In capped
octabedron and capped wigonal pis, one ligand (the seventh ligand) occupy ane of the eight faces.
Some examples af complexes of coordination number 7 are[Z:F; 1°, [MO(CNR) + [REOCI, I?"
and {U02(H20)5 + +
Coordination Number,
Coordination number 8 als can notbereganied as common. The possible geometries for complexes
of coordination number $ are square anipismatc {Figure 2.12(0)) and the trigonal dodecahedral
[Figure 2.12(6]. The two famous examples with he geometries are shown in Figure 2.12.
Éd
An anote o of stint ng rampes, eld gon! dri age
LU our treo oon es host ve pu rough le he tees
29) ing ina gona amp
ithe ligands ofa regular octahedra complex lik [Co(NE 61 replaced by chelating ligands like
-sttylenediamine, Ny —CHly —CHlp —Nip 0 form [Cofen); +, the of the regla
cerca Oh wD; brat ane NY
‘The complexes having trigonal prismatic geomet (Figure 2,10 re rar, but have been ford in
ysul latices of sulphides of heavy mets, for example, MoS; and WS», Tegoral primas.
complexes of d° configuration sch as (Z(CHsJ "and (W(CHs)] have alto been lola The
tigonal prismatic structure of{Re(S;C2Phz)s Js shown in Figure 2.10
Higher Coordination Numbers
‘Coordination number 7 isnot common. However, its encountered for a few 3d: and some dd: and
‘sd- metal complexes, where the larger central metal ion can accommodate mote than six ligands. The
geometries corresponding 10 the coordination number 7 are pentagonal bipyramidal, a capped
‘octahedcon and a capped trigona! prism (These three geometries are shown in Figure 2.11). In capped
octabedron and capped wigonal pis, one ligand (the seventh ligand) occupy ane of the eight faces.
Some examples af complexes of coordination number 7 are[Z:F; 1°, [MO(CNR) + [REOCI, I?"
and {U02(H20)5 + +
Coordination Number,
Coordination number 8 als can notbereganied as common. The possible geometries for complexes
of coordination number $ are square anipismatc {Figure 2.12(0)) and the trigonal dodecahedral
[Figure 2.12(6]. The two famous examples with he geometries are shown in Figure 2.12.
Coordination Number 9
‘Coordination mumber 9 is shown by some f- block elements because of their larger size. Some
important examples ae (Lo(Hz0)9]°* [NACH30}9}°*. The examples of coordination munter 9 ofthe
de block elements are [ch 1?" and [Rel]. The structure of {Rett} is shown in Figure 2.13
Coordination Number 10
Coordination number 10 is encountered in complexes of block M°* ions. For example, in
{[TH(OX) (20). |, Thhas coordination number of 10, The higher coordination aumbersarerare with
de block M™ ions because ther smaller size may be responsible for he Hgsnd-igand repulsion when
‘they approach the meta on
Coordination Number 12
(Coordination number {2 j alo encountered in complexes of the block M* ions. An important
‘example is{Ce(NO5 11° in which each NOS ligand behaves as bidentate ligand. Ifthe size of a metal
ation is small then NO} behaves as monodentate ligand. Uf, for instance, it ets bidentate Ligand with
smaller cation, there will be stain betiveen two dónor O-atoms of a NOF and the complex becomes
unstable
the sizeof metal cation becomes ages than there wil be a small or negligible stain between the
two donorO atom of NOF when it coordinated tometal ion and thus NO3 behavesasbidenaeligand.
‘thd omen Coat Gaia
ASOMERISM;
Isomers are compounds with he same chemical composition but diffrent rangement of
consu toms and phenomenon of existence ofisomer is called isomerism Since their tos
arranged differently, deren, isomers are different compounds with diferent reactivity andlor
diferent physical propres such as colour, meting and boiling pins, nd shi). Isomers
mainly classified ino wo types. Structural (oe consiuional) and steroisomeri „ach ofthese
further sub lasified as:
Iomerism
—— —
Structural isomerim Sterioisomerism
Torization isomerism > Geometrical isomerism
gate isomerism Optical isomersn
Likegefomerism
Coondinain someon
> Coantiratin gain mern,
tige im
Polymedzatica isomers
Structural Isomerism
Isomers thet have differ atomo-stom bonding are called structure isomers. In coordination
compounds, structural iomrion mise due to different connections (or bonding) between meta and
ligands.
(1) Konization Homer : In these tomers there is exchange of igands between coordination
sper and ionization sper (alld as counter on). These isomers give iferenions when dissolved
‘water. For example, [Co(NH3)sBr]804 and [Co(NH5)5(S04)] Br are ionization isomers. These
isomers give diferent ions in aqueous solution and show different properties.
(ICON) BSO, ised violet and {CNE (SO, Br is red.
©) In aqueous sation, (CON: )sBr]S0, gives white precipitate of BaSO4 on ration with
Bac whereas it does nt give any precipitate with AgNO). This indicates tat SO" ion is preseatin
‘nization sper.
+ (Colitis) 5833804 "> [Co(NA3)s Be” + BeSO4
Ae cn
— et
be
On the other hand, (Co(NHs)s(S04)]Br gives cream coloured peciptate of AgBr with AgNOs
and it does not give any precipitate with BaCl}. This indicates that Br” ion is present outside the
coordination sphere |
EE
‘Coordination mumber 9 is shown by some f- block elements because of their larger size. Some
important examples ae (Lo(Hz0)9]°* [NACH30}9}°*. The examples of coordination munter 9 ofthe
de block elements are [ch 1?" and [Rel]. The structure of {Rett} is shown in Figure 2.13
Coordination Number 10
Coordination number 10 is encountered in complexes of block M°* ions. For example, in
{[TH(OX) (20). |, Thhas coordination number of 10, The higher coordination aumbersarerare with
de block M™ ions because ther smaller size may be responsible for he Hgsnd-igand repulsion when
‘they approach the meta on
Coordination Number 12
(Coordination number {2 j alo encountered in complexes of the block M* ions. An important
‘example is{Ce(NO5 11° in which each NOS ligand behaves as bidentate ligand. Ifthe size of a metal
ation is small then NO} behaves as monodentate ligand. Uf, for instance, it ets bidentate Ligand with
smaller cation, there will be stain betiveen two dónor O-atoms of a NOF and the complex becomes
unstable
the sizeof metal cation becomes ages than there wil be a small or negligible stain between the
two donorO atom of NOF when it coordinated tometal ion and thus NO3 behavesasbidenaeligand.
‘thd omen Coat Gaia
ASOMERISM;
Isomers are compounds with he same chemical composition but diffrent rangement of
consu toms and phenomenon of existence ofisomer is called isomerism Since their tos
arranged differently, deren, isomers are different compounds with diferent reactivity andlor
diferent physical propres such as colour, meting and boiling pins, nd shi). Isomers
mainly classified ino wo types. Structural (oe consiuional) and steroisomeri „ach ofthese
further sub lasified as:
Iomerism
—— —
Structural isomerim Sterioisomerism
Torization isomerism > Geometrical isomerism
gate isomerism Optical isomersn
Likegefomerism
Coondinain someon
> Coantiratin gain mern,
tige im
Polymedzatica isomers
Structural Isomerism
Isomers thet have differ atomo-stom bonding are called structure isomers. In coordination
compounds, structural iomrion mise due to different connections (or bonding) between meta and
ligands.
(1) Konization Homer : In these tomers there is exchange of igands between coordination
sper and ionization sper (alld as counter on). These isomers give iferenions when dissolved
‘water. For example, [Co(NH3)sBr]804 and [Co(NH5)5(S04)] Br are ionization isomers. These
isomers give diferent ions in aqueous solution and show different properties.
(ICON) BSO, ised violet and {CNE (SO, Br is red.
©) In aqueous sation, (CON: )sBr]S0, gives white precipitate of BaSO4 on ration with
Bac whereas it does nt give any precipitate with AgNO). This indicates tat SO" ion is preseatin
‘nization sper.
+ (Colitis) 5833804 "> [Co(NA3)s Be” + BeSO4
Ae cn
— et
be
On the other hand, (Co(NHs)s(S04)]Br gives cream coloured peciptate of AgBr with AgNOs
and it does not give any precipitate with BaCl}. This indicates that Br” ion is present outside the
coordination sphere |
EE
ISIE EE Goal
BAe
[ON CANINA
RN rase
No Precipitate
Some the examples of ionization isomerim are:
DICH sC1}90, a0d{COCNH)5(804)]C1
teats) OO, ¡JO and [Co(NH )s(SO4 NO;
CDF) JB and (NEL a Br JC
A fCo(e03C2 N02 )ISCN, [Co(en)¿CI(SCNJINO; and[Co(en) (NO ASOUJAL
() Hate amer : When water molecules are exchange bowen océan sphere and
ization see te resulting isomer are called hydrate sans For example, hy sones given
5 CIAO ate: (CHHyO}gICl, (viole, (CO) OCA HO. Gale ren) and
(HO) ICLAO (ar green). These iomer ive irn! properties
(These om have dierent colours.
) When these isomers react with AgNO3 solution, 3, 2 and 1 chore ons get precipitated
spectively.
{Cr 0101601, (or Gi 0)6}* +345)
(Cr) Ce, «M0 2 (ar (HO LCI 1104245016)
LC (HO) CC 130 (Cr LOC" 210 + Ag)
i)(CALIZO)6]Cly dos not loss water over cone HySO.,
(rt130), 101 55% (cxHh,0}5}01 Oo change)
{CeG,0); CC HO lose one water moleeute over one. H,S0,
[Cr (a0)s CIA +10 (CO) + KL
[Cr (120) Ci, ICI. 20 loses two water molecules over conc. Hy$Os.
{Cr 20). Cta JC1-2H630 428%, [Cy (40), Cl }C1+2H,0
©) Linkage Isomerism : Linkage isomers arise when an ambideniate ligand can coordinate o a
tal cation though cer ofthe two different donor ato
Forexample, in complexes containing NO} ion as ligand, may oordinateto meta ction through
ther Natom oc O-tom. The linkage isomers containing NO} ion as ligand are :
NH) (NOa)}, Nator is coordinated to CoP and (Co(NHS)s(ONO}F*, Oo is
pordinated to Co™. Some other examples of linkage isomers are
COOH): SCHICH and(Co (NH) (NCSIICl2
ICON) NO») and[Coten)z (ONO)2)"
GPA (PP3)2 (SCA) Jand [Pa (PPh 32 (NCS)2]
In most discrete complexes cyanide, CN does not behaves as am ambidentate ligand. it always
bonds though the carbon atom because ofthe songer x-bondingin his mode. Homener, CN behaves
as ambidetate ligand in inks pe isomers such as cis-{Coften)(CN)2}* and cisfCo(wien)(NC), J*. In
Sarge number of polymeric complexes, CN” acts as ambidenae bridging ligand. For example, in
prestan blue and turbull blue, both have same structure, iniensely blu colour, same isocyenide
framework as shown blow:
4
In both russian blue and tumbul blue, hexacoondinaed ow spn (1) is bonded through the
carton sions andexzcoodinated high pin Fol) is bonded though the nirogen atoms of cyanide
Fran clon ei nn pon
4 ep
Fe + FC) — FAFACNI hs Twas
Frets
“Tumbull blue is formed by addition of K y [Fe(CN)5 solution to Fe?* ions solution.
FEAS" — Real FCM
E Toalla
Shriverand etalreportedan interesting example of linkage isomerism, Wen K[C ON) solution
is added to Fe ins solution a brick ed precipitate is obtained which tans dark grea on heating at
100°C.
FR (CNET — KEN
des
wc
u
KEN)
Det
‘These isomers bave the following structures
u u u u
1 Fe NO-Ö CN —Fe—NC—Cr CN
ick Ret
u m m
2 Fe—ON NO BC …
Duk gam
BAe
[ON CANINA
RN rase
No Precipitate
Some the examples of ionization isomerim are:
DICH sC1}90, a0d{COCNH)5(804)]C1
teats) OO, ¡JO and [Co(NH )s(SO4 NO;
CDF) JB and (NEL a Br JC
A fCo(e03C2 N02 )ISCN, [Co(en)¿CI(SCNJINO; and[Co(en) (NO ASOUJAL
() Hate amer : When water molecules are exchange bowen océan sphere and
ization see te resulting isomer are called hydrate sans For example, hy sones given
5 CIAO ate: (CHHyO}gICl, (viole, (CO) OCA HO. Gale ren) and
(HO) ICLAO (ar green). These iomer ive irn! properties
(These om have dierent colours.
) When these isomers react with AgNO3 solution, 3, 2 and 1 chore ons get precipitated
spectively.
{Cr 0101601, (or Gi 0)6}* +345)
(Cr) Ce, «M0 2 (ar (HO LCI 1104245016)
LC (HO) CC 130 (Cr LOC" 210 + Ag)
i)(CALIZO)6]Cly dos not loss water over cone HySO.,
(rt130), 101 55% (cxHh,0}5}01 Oo change)
{CeG,0); CC HO lose one water moleeute over one. H,S0,
[Cr (a0)s CIA +10 (CO) + KL
[Cr (120) Ci, ICI. 20 loses two water molecules over conc. Hy$Os.
{Cr 20). Cta JC1-2H630 428%, [Cy (40), Cl }C1+2H,0
©) Linkage Isomerism : Linkage isomers arise when an ambideniate ligand can coordinate o a
tal cation though cer ofthe two different donor ato
Forexample, in complexes containing NO} ion as ligand, may oordinateto meta ction through
ther Natom oc O-tom. The linkage isomers containing NO} ion as ligand are :
NH) (NOa)}, Nator is coordinated to CoP and (Co(NHS)s(ONO}F*, Oo is
pordinated to Co™. Some other examples of linkage isomers are
COOH): SCHICH and(Co (NH) (NCSIICl2
ICON) NO») and[Coten)z (ONO)2)"
GPA (PP3)2 (SCA) Jand [Pa (PPh 32 (NCS)2]
In most discrete complexes cyanide, CN does not behaves as am ambidentate ligand. it always
bonds though the carbon atom because ofthe songer x-bondingin his mode. Homener, CN behaves
as ambidetate ligand in inks pe isomers such as cis-{Coften)(CN)2}* and cisfCo(wien)(NC), J*. In
Sarge number of polymeric complexes, CN” acts as ambidenae bridging ligand. For example, in
prestan blue and turbull blue, both have same structure, iniensely blu colour, same isocyenide
framework as shown blow:
4
In both russian blue and tumbul blue, hexacoondinaed ow spn (1) is bonded through the
carton sions andexzcoodinated high pin Fol) is bonded though the nirogen atoms of cyanide
Fran clon ei nn pon
4 ep
Fe + FC) — FAFACNI hs Twas
Frets
“Tumbull blue is formed by addition of K y [Fe(CN)5 solution to Fe?* ions solution.
FEAS" — Real FCM
E Toalla
Shriverand etalreportedan interesting example of linkage isomerism, Wen K[C ON) solution
is added to Fe ins solution a brick ed precipitate is obtained which tans dark grea on heating at
100°C.
FR (CNET — KEN
des
wc
u
KEN)
Det
‘These isomers bave the following structures
u u u u
1 Fe NO-Ö CN —Fe—NC—Cr CN
ick Ret
u m m
2 Fe—ON NO BC …
Duk gam
IE
9 Coordiñation Isomerism: In complexes when be cation andanion both are complexions there
nay be exchange of ligands between these two complex ions engin coordination somes. nthe
hits ofthese isomers, the central metal eatin in the wo corinatn sphere may be the same or
dite.
Som example o coordination isomer ar given low
(ICO (NH) [CE (CN) and (Cr (NH) CO(CNE
(Co) PE CL Jane (NE CH CU]
Co ess ICH (CN ane [Cr en ICON]
A wy w m
(iv) (PU Ja (Pt Clg) and (Pt (NH «CI» PECL)
(ICA) He (CAD and Cr (NE (CHa CNE) (CA
(©) Coordination Postion Isomerism : I biäing camplexs an exchange of aon-bridging
ligands between two metal cations give rise to coordination poston iomecisr,
le
Forexample
a} NE 9
LUE a
OLE): Co Co (NI): Cu
sa o Go ch
NE
TER: de
and (G(H3N)3 Co Co; )s CH
à No, 7
on
LS pa
DL, A
ox
and (CUADO > Coens ch?"
on
‘6 Ligand Isomerism : If ligand tel exists in two or more isomeric forms, then the complexes
containing such ligands also exist in isomeri forms, Examples of isomeric ligands are
a an mi, a
!
NH NH) Ni NH;
12 ipo —
SETE ETT
Dem and padi.
qe NH ba
d CH, O
ours misión pte
Teen a Coordi
AECE
nen Boeing mira CT CC opi
Les
ES
vain
7 =
7. Polyméizañion Isömeriimn : Polymer are notrslisomen. These isomers have srt emperca!
ferme instead of molecular formula. All hese some have the same rato 0 metal lomo sad the
ligands them. Polymerization canbe illustrated by th coordination polymers of: 2* and Co
il ions,
{Ps )aCI]
NES) PCI]
Pas) JEPANH ICA: Ta
{Pugs CPC)
9 Coordiñation Isomerism: In complexes when be cation andanion both are complexions there
nay be exchange of ligands between these two complex ions engin coordination somes. nthe
hits ofthese isomers, the central metal eatin in the wo corinatn sphere may be the same or
dite.
Som example o coordination isomer ar given low
(ICO (NH) [CE (CN) and (Cr (NH) CO(CNE
(Co) PE CL Jane (NE CH CU]
Co ess ICH (CN ane [Cr en ICON]
A wy w m
(iv) (PU Ja (Pt Clg) and (Pt (NH «CI» PECL)
(ICA) He (CAD and Cr (NE (CHa CNE) (CA
(©) Coordination Postion Isomerism : I biäing camplexs an exchange of aon-bridging
ligands between two metal cations give rise to coordination poston iomecisr,
le
Forexample
a} NE 9
LUE a
OLE): Co Co (NI): Cu
sa o Go ch
NE
TER: de
and (G(H3N)3 Co Co; )s CH
à No, 7
on
LS pa
DL, A
ox
and (CUADO > Coens ch?"
on
‘6 Ligand Isomerism : If ligand tel exists in two or more isomeric forms, then the complexes
containing such ligands also exist in isomeri forms, Examples of isomeric ligands are
a an mi, a
!
NH NH) Ni NH;
12 ipo —
SETE ETT
Dem and padi.
qe NH ba
d CH, O
ours misión pte
Teen a Coordi
AECE
nen Boeing mira CT CC opi
Les
ES
vain
7 =
7. Polyméizañion Isömeriimn : Polymer are notrslisomen. These isomers have srt emperca!
ferme instead of molecular formula. All hese some have the same rato 0 metal lomo sad the
ligands them. Polymerization canbe illustrated by th coordination polymers of: 2* and Co
il ions,
{Ps )aCI]
NES) PCI]
Pas) JEPANH ICA: Ta
{Pugs CPC)
id Vane ra AN
(Co(NH3}3(NO2)3]
ICON; Je 1ICHNO26]
[CORE )4 (NO 2 Ja HCOCNH 2 (NO2)4]
“The isomers in which te same types and number of ligands are coordinated fo the metal atom oc
cation but with different spatial araagemens are elle teriisomes. In other words, teroisomers are
isomers that diffe ony in the spatial arrangement of ligands coordinated to metal cation or atom.
Sterioisomerism is classified into two types
(1) Geometrical isomerism
€) Optical isomerissa
(1) Geometrical Isomerism
Steroisomers in which the relative postions ar oientations ofthe ligands or more specifically
dono: stos rund the metal ction is rent are called geometrical isomers and this phenomenon is
called geometrical isomerism, Geometiel isomers can ot be inter-conveted without breaking of ML
bonds. Geometrical isomers exists only in pais none somes the two particular ligands are adjacent to
cach oer and in theater the two are in opposite sides in the structural formula, Thus, the isomer in
which two particular ligands (citer identical or non-identical) occupy the adjacent positions ofeach
oher is called cis-isomer and th isomer in which two particular ligands occupy opposite postions to
cach ater is called ran.isomer (The atin word cis means nex 10, trans means actos) ci- ad ran-
isomers are different compounds with different popenes like melting points, dipole moments,
solubility, colour and chemical properties For example cis - [PINES Cl Ji polar molecule ad is
tore soluble in water than rans- PL (NH )2C molecule which have zero dipole moment. Als cis-
[Pe(NH3)2Cla] called cisplain is an efeivo amcancer drug where as the trans isomer is
physiologically inactive. Geometrical isomerism is mast common in complexes having coordination
number of 4 and 6, The complexes whch exhibit coordination numbers 2 and 3 do not exhibi
cal isomerism,
Jeometrical isomerism in complexes which exhibit coordination number 4
(A) Tetrhedral Complexes: Teahedral complexes donot exhibit geometrical isomerism whether
the ligands are same or diferent because all the ligands inthis geometry are a adjacent postions
relative to each othe, ie, each ligand is resent at 1098 from each ofthe ater thee ligands.
(8) Square Planar Complexes:
{Mag} [Mash] [MAA], [MAAabI"* and (M(AA)22}"* ype square planar
complexes do not exbbit geometrical omis because all the possible spatial aangeneat
ligands round the metal cation is the same, m Ei
(Ma zb2}"* type Complexes:
Examples of hs pe of complexes ar [PLN )2C1,], [PL(py)¿Cla] ete. which exit
geometrical isomerism. cis- and irons isomers of [Pt ‘example, are shown in
Fest (PLONE )2Cla)} , for example, are shown
0
Gi [Ma be|"* type Complexes:
Examples of this pe of completes am : (PNG pyCU, (PON QUA,
(e(NHy)2(NO2}CH et. which exhibit geometical isomerism. cise and ans isomers of
[Pt py)a (NHs CI] for example, ar shown in Figure 2.16,
(iy) [Mabed]** type Complexes:
‘Square planar completes of is type exist in thre isomeric forms
‘The dhe somes of PE) AD], can be obtained by Bing on isd,
is, atome udn pl catre ans, ony on ren to) Fu 217 Se
(Co(NH3}3(NO2)3]
ICON; Je 1ICHNO26]
[CORE )4 (NO 2 Ja HCOCNH 2 (NO2)4]
“The isomers in which te same types and number of ligands are coordinated fo the metal atom oc
cation but with different spatial araagemens are elle teriisomes. In other words, teroisomers are
isomers that diffe ony in the spatial arrangement of ligands coordinated to metal cation or atom.
Sterioisomerism is classified into two types
(1) Geometrical isomerism
€) Optical isomerissa
(1) Geometrical Isomerism
Steroisomers in which the relative postions ar oientations ofthe ligands or more specifically
dono: stos rund the metal ction is rent are called geometrical isomers and this phenomenon is
called geometrical isomerism, Geometiel isomers can ot be inter-conveted without breaking of ML
bonds. Geometrical isomers exists only in pais none somes the two particular ligands are adjacent to
cach oer and in theater the two are in opposite sides in the structural formula, Thus, the isomer in
which two particular ligands (citer identical or non-identical) occupy the adjacent positions ofeach
oher is called cis-isomer and th isomer in which two particular ligands occupy opposite postions to
cach ater is called ran.isomer (The atin word cis means nex 10, trans means actos) ci- ad ran-
isomers are different compounds with different popenes like melting points, dipole moments,
solubility, colour and chemical properties For example cis - [PINES Cl Ji polar molecule ad is
tore soluble in water than rans- PL (NH )2C molecule which have zero dipole moment. Als cis-
[Pe(NH3)2Cla] called cisplain is an efeivo amcancer drug where as the trans isomer is
physiologically inactive. Geometrical isomerism is mast common in complexes having coordination
number of 4 and 6, The complexes whch exhibit coordination numbers 2 and 3 do not exhibi
cal isomerism,
Jeometrical isomerism in complexes which exhibit coordination number 4
(A) Tetrhedral Complexes: Teahedral complexes donot exhibit geometrical isomerism whether
the ligands are same or diferent because all the ligands inthis geometry are a adjacent postions
relative to each othe, ie, each ligand is resent at 1098 from each ofthe ater thee ligands.
(8) Square Planar Complexes:
{Mag} [Mash] [MAA], [MAAabI"* and (M(AA)22}"* ype square planar
complexes do not exbbit geometrical omis because all the possible spatial aangeneat
ligands round the metal cation is the same, m Ei
(Ma zb2}"* type Complexes:
Examples of hs pe of complexes ar [PLN )2C1,], [PL(py)¿Cla] ete. which exit
geometrical isomerism. cis- and irons isomers of [Pt ‘example, are shown in
Fest (PLONE )2Cla)} , for example, are shown
0
Gi [Ma be|"* type Complexes:
Examples of this pe of completes am : (PNG pyCU, (PON QUA,
(e(NHy)2(NO2}CH et. which exhibit geometical isomerism. cise and ans isomers of
[Pt py)a (NHs CI] for example, ar shown in Figure 2.16,
(iy) [Mabed]** type Complexes:
‘Square planar completes of is type exist in thre isomeric forms
‘The dhe somes of PE) AD], can be obtained by Bing on isd,
is, atome udn pl catre ans, ony on ren to) Fu 217 Se
other examples of such type of square planar complexes which can exis in thre isomeric ons are
[BUCH (NH )CIBH, [Pt Coy} (NH) (NEO) (NO )]* ete
(6) [M(AB)¿]** type Complexes :
Here Mis central mealcaonand AB a unsymmetical bidentate and which A and Bare
to différent door alors. Examplesofsuch ype of complexes ar: [Pt (ly) [Cu (ly) Jete. The cis
and trans isomers of{P* (ly) ar bosta in Figure 2.1.
(i) Bridged Binuclear Square Planar Compleres of Mig by (ype:
‘The bridged bimclear square plana complex of Ma 2b4 type can exist a three isomeric fonos
(cis. trans- and unsymemei) Th tine sori forms of {Pt (PEs CH for example aestownin
Figure 219, Bt only ci and rans-somes of most of the complexes ofthis ype have bee fund.
¿o ee
Bye Na” Nes
NN
a’ Na’ No
EN.
a’ Na’ Ve
CS
(vi) Square plan complexes with symmetic bidentate ligands carrying one or mor substituents
can form goometricl isomers. Foc example, [Pt(pn)a 1%" exists in cis» and trans -isomere forms
igure 220 initie math pop ar is and ans repesheiy wit espct theme plane
ofthe ing atoms.
An another example of complex is that having bidentate ligands wit
th two methyl substiuents as
shown ia Figure 221
GeometcicalIsomecsa in Octshedral Complexes
Im an octahedral complex a metal cation will present in the centre ofan ocabedron and the six
ligands occupy the si comers mumbere from 1 10 6 as shown in Figure 2.2.
[BUCH (NH )CIBH, [Pt Coy} (NH) (NEO) (NO )]* ete
(6) [M(AB)¿]** type Complexes :
Here Mis central mealcaonand AB a unsymmetical bidentate and which A and Bare
to différent door alors. Examplesofsuch ype of complexes ar: [Pt (ly) [Cu (ly) Jete. The cis
and trans isomers of{P* (ly) ar bosta in Figure 2.1.
(i) Bridged Binuclear Square Planar Compleres of Mig by (ype:
‘The bridged bimclear square plana complex of Ma 2b4 type can exist a three isomeric fonos
(cis. trans- and unsymemei) Th tine sori forms of {Pt (PEs CH for example aestownin
Figure 219, Bt only ci and rans-somes of most of the complexes ofthis ype have bee fund.
¿o ee
Bye Na” Nes
NN
a’ Na’ No
EN.
a’ Na’ Ve
CS
(vi) Square plan complexes with symmetic bidentate ligands carrying one or mor substituents
can form goometricl isomers. Foc example, [Pt(pn)a 1%" exists in cis» and trans -isomere forms
igure 220 initie math pop ar is and ans repesheiy wit espct theme plane
ofthe ing atoms.
An another example of complex is that having bidentate ligands wit
th two methyl substiuents as
shown ia Figure 221
GeometcicalIsomecsa in Octshedral Complexes
Im an octahedral complex a metal cation will present in the centre ofan ocabedron and the six
ligands occupy the si comers mumbere from 1 10 6 as shown in Figure 2.2.
pre
In cis-isomers the wo sila igaads or some times two diferen ligands of interest occupy the
corners of ocahedrl adjacent to one another. In cis some the sae ligands ocupy either ofthe
positions (1,2) , (1,3), (1,4), (1,5), (2,3), (3,4), (4,5), (5,2), (6,2) (6,3), (6,4) or (6,5). In trans- isomers
{hese ligands ee ving opposite 1 one another on straight ine which passes through the centre the
tctabedton, In an «mer the two ligands under consideran wl occupy either of ie positions
(9,08) 04 6.5.
nee al he comers of a regular octahedron ar equivalent, hee ato geometrical isomers of
‘complexes of the type[Mag] "* [Ma sbJ"* and[M (AA); ]where AA isa symmetric bidentate ligand.
‘The fllowing types of octahedral complexes exhibit geomet omen :
@ [May b3]"* type Complexes :
“The compleres ofthis type exist in cis - and iran - isomeric for. Examples of this type of
complexes are ; (Co (NH3)4Cl2 ]", [Co(NH}¢(NOz}a]* te. The ci and trans- isomers of
[Co(NH3)4Cl2]* are shown in Figure 2.23.
two” ligands ecupy positions opposite to eath otter (ie. 1,9, Te cs somes has bue-voet
colour ies ans some as green colo
{G{Ma4bel"® type Complexes:
The complexes fthis type ls existin cis- and ans ise Examples ofthis type of complexss
are : (Co{NHLs)¢(Hz0)CH}” [Co(NHs)4 EYE?" ete. The cis- and trans isomers of
(Coi) (HO)CI* ae shown in Figure 224
Incls-iomerH;OandCI” Ligand re adjacent posion wheeainrans-isomers these ligands
are on oppose postions
(i) Facial nd Meridional Tomers
Infacialisumess re ideal donor atoms li ont comers of wire and in meridional
isomers re dental door atoms lie an the comes a plan isting he complex, There ae fout
‘ype complex which exist in ac and mersomerie forms,
@)UMasby}"* type Complexes : 2
Some examples of this type of complexes are :[Co(his)sCls}Co(NH) (NO2)3 1,
[Ce QSHs CI, Jt Facial (or cis) and meridional (or ans) isomers of [Ca (Hs) sCls Jareshownin
Figue 225,
wn
pos
Infacisomex, the tree CCC bond angles are 0" whl the merisomer, two Cl—Co—Cl
Bond angles 90" andenes 180. Also we can say hatin meso tires CT ligands iin one plane
and ve NH, ganic in perpendicular plane. This complex called meridional because each st
‘of ligands can be regarded as lying on a meridian ofa sphere the largest circle that can be drawn on the
surface of the sphere).
(0) IM (AB)31"* type Complexes =
Inthistypeofeomplexes AB is an unsyanmetri bidentate ligand, Well known example of this type
‘of complexes ae :[Co(ly)5 Jan [Cr (hy) ], wher ely NH, Ci, COO”. The facial nd meridional
‘somes fo (Jae sown in Figure 2.26,
In cis-isomers the wo sila igaads or some times two diferen ligands of interest occupy the
corners of ocahedrl adjacent to one another. In cis some the sae ligands ocupy either ofthe
positions (1,2) , (1,3), (1,4), (1,5), (2,3), (3,4), (4,5), (5,2), (6,2) (6,3), (6,4) or (6,5). In trans- isomers
{hese ligands ee ving opposite 1 one another on straight ine which passes through the centre the
tctabedton, In an «mer the two ligands under consideran wl occupy either of ie positions
(9,08) 04 6.5.
nee al he comers of a regular octahedron ar equivalent, hee ato geometrical isomers of
‘complexes of the type[Mag] "* [Ma sbJ"* and[M (AA); ]where AA isa symmetric bidentate ligand.
‘The fllowing types of octahedral complexes exhibit geomet omen :
@ [May b3]"* type Complexes :
“The compleres ofthis type exist in cis - and iran - isomeric for. Examples of this type of
complexes are ; (Co (NH3)4Cl2 ]", [Co(NH}¢(NOz}a]* te. The ci and trans- isomers of
[Co(NH3)4Cl2]* are shown in Figure 2.23.
two” ligands ecupy positions opposite to eath otter (ie. 1,9, Te cs somes has bue-voet
colour ies ans some as green colo
{G{Ma4bel"® type Complexes:
The complexes fthis type ls existin cis- and ans ise Examples ofthis type of complexss
are : (Co{NHLs)¢(Hz0)CH}” [Co(NHs)4 EYE?" ete. The cis- and trans isomers of
(Coi) (HO)CI* ae shown in Figure 224
Incls-iomerH;OandCI” Ligand re adjacent posion wheeainrans-isomers these ligands
are on oppose postions
(i) Facial nd Meridional Tomers
Infacialisumess re ideal donor atoms li ont comers of wire and in meridional
isomers re dental door atoms lie an the comes a plan isting he complex, There ae fout
‘ype complex which exist in ac and mersomerie forms,
@)UMasby}"* type Complexes : 2
Some examples of this type of complexes are :[Co(his)sCls}Co(NH) (NO2)3 1,
[Ce QSHs CI, Jt Facial (or cis) and meridional (or ans) isomers of [Ca (Hs) sCls Jareshownin
Figue 225,
wn
pos
Infacisomex, the tree CCC bond angles are 0" whl the merisomer, two Cl—Co—Cl
Bond angles 90" andenes 180. Also we can say hatin meso tires CT ligands iin one plane
and ve NH, ganic in perpendicular plane. This complex called meridional because each st
‘of ligands can be regarded as lying on a meridian ofa sphere the largest circle that can be drawn on the
surface of the sphere).
(0) IM (AB)31"* type Complexes =
Inthistypeofeomplexes AB is an unsyanmetri bidentate ligand, Well known example of this type
‘of complexes ae :[Co(ly)5 Jan [Cr (hy) ], wher ely NH, Ci, COO”. The facial nd meridional
‘somes fo (Jae sown in Figure 2.26,
I facial isomer three N-donor atoms occupy the comers of a gel face and the three O-donor
‘toms occupy the comes of another trigonal face and in other words, we can say that the facial some,
‘the three possible N—Co—N bond angles are 90. In meridional isomer twoN—Co—N bond angles are
90° and one is 180"
(e) The complex (Co (dies) (NOz)) (Where dien «NH, —CHy —CH — NH — CH —CHz|
NH) also exists in facial and meridional isomeric forms as shown ia Figure 2.27
228
Infact isomers the three N-donor atoms ofa den igand lion the comers of trigonal fice Le, the
three posible N—Co—N bond angles ora dien ligand ate 90. In a meridional isomer two N—Co—N
‘ond angles and one N—Co—N bond angle fora die ligand are 0° and 180 respectively.
9) Mazbaca]"* type Complexes:
‘The complex ion, (Pt (NH3}2 Ps} C2} is an example of[Maabac21"* type complexes. The
posible geometrical isomers ae shown in Figure 228,
‘toms occupy the comes of another trigonal face and in other words, we can say that the facial some,
‘the three possible N—Co—N bond angles are 90. In meridional isomer twoN—Co—N bond angles are
90° and one is 180"
(e) The complex (Co (dies) (NOz)) (Where dien «NH, —CHy —CH — NH — CH —CHz|
NH) also exists in facial and meridional isomeric forms as shown ia Figure 2.27
228
Infact isomers the three N-donor atoms ofa den igand lion the comers of trigonal fice Le, the
three posible N—Co—N bond angles ora dien ligand ate 90. In a meridional isomer two N—Co—N
‘ond angles and one N—Co—N bond angle fora die ligand are 0° and 180 respectively.
9) Mazbaca]"* type Complexes:
‘The complex ion, (Pt (NH3}2 Ps} C2} is an example of[Maabac21"* type complexes. The
posible geometrical isomers ae shown in Figure 228,
rn
AS
(UM abedef]"* type Complexes: [Pr(py) (NS (NO2 (CIB
“There is only one coordination compound, ofthis type. This compound can existin fen possible
isomerie forms bat only tte isomers have been isolated
(Wi) IM (AA)2 22)” type Complexes :
Here AA isa symmetric bidentate ligand, and‘a"is a monodentate ligand. Some example ofthis type
af complexes ae; {Co(en),Ca}" {Caer (NO a] *[Co(en)2(NOs 1 (Rh (C:04)2 Ch
| eto. The possible geometrical isomers {Co(en) Cl, }* are shown in Figure 2.30.
al
(ei) IM (AA) 2ab] type Compleres :
Some examples of this type of complexes are : [Co(en)2 (NH; ICI", [Cole)2 CP",
[CH(OX)2(NOzXC1]” et. The goomeriel isomers of [Cofen) (NH )CIP*areshown in Figure 2.31.
vail ont
Kal u.
Ineis- isomer the ligands NH and” area adjacent positions whereasin rans-isomerthe ligand
NE: and CI” are opposite to one anote
(il) (M(AA)ag ba} type Complexes:
Some examples ofthistypeofeomplexes are: Co(en)(NH)2Cl2J* ,[Co(ea)(9y}2Cl2J" te. The
possible geometrical isomers of Co(ex)(NH3)2Cla} ate shown in Figure 2.32.
tn isomer (D bth he NI ligands ad bed he CT” ligands are on adjacent postions nisomer (D,
“he NH; ligand ax opposte andthe” ligands ar a the adjacent postions whereasin sore (the
CI” ligadas opposite and the NH and re on adjacent positions
(EX) (CAB) 221" type Complexes :
“An example of this type of complex is [Co(#y)2Cla ]” ion. The geometrical isomers ofthis
complex ae shown in Figure 23
GIM(AB)zab"* type Compleses :
“An example of his type of complexes is [Co(ey)2 (NH py)}" ion. The gcomercal isomers of
this complex ion are shown in Figure 2. M.
AS
(UM abedef]"* type Complexes: [Pr(py) (NS (NO2 (CIB
“There is only one coordination compound, ofthis type. This compound can existin fen possible
isomerie forms bat only tte isomers have been isolated
(Wi) IM (AA)2 22)” type Complexes :
Here AA isa symmetric bidentate ligand, and‘a"is a monodentate ligand. Some example ofthis type
af complexes ae; {Co(en),Ca}" {Caer (NO a] *[Co(en)2(NOs 1 (Rh (C:04)2 Ch
| eto. The possible geometrical isomers {Co(en) Cl, }* are shown in Figure 2.30.
al
(ei) IM (AA) 2ab] type Compleres :
Some examples of this type of complexes are : [Co(en)2 (NH; ICI", [Cole)2 CP",
[CH(OX)2(NOzXC1]” et. The goomeriel isomers of [Cofen) (NH )CIP*areshown in Figure 2.31.
vail ont
Kal u.
Ineis- isomer the ligands NH and” area adjacent positions whereasin rans-isomerthe ligand
NE: and CI” are opposite to one anote
(il) (M(AA)ag ba} type Complexes:
Some examples ofthistypeofeomplexes are: Co(en)(NH)2Cl2J* ,[Co(ea)(9y}2Cl2J" te. The
possible geometrical isomers of Co(ex)(NH3)2Cla} ate shown in Figure 2.32.
tn isomer (D bth he NI ligands ad bed he CT” ligands are on adjacent postions nisomer (D,
“he NH; ligand ax opposte andthe” ligands ar a the adjacent postions whereasin sore (the
CI” ligadas opposite and the NH and re on adjacent positions
(EX) (CAB) 221" type Complexes :
“An example of this type of complex is [Co(#y)2Cla ]” ion. The geometrical isomers ofthis
complex ae shown in Figure 23
GIM(AB)zab"* type Compleses :
“An example of his type of complexes is [Co(ey)2 (NH py)}" ion. The gcomercal isomers of
this complex ion are shown in Figure 2. M.
&
x
s
e:
(XI) Oetahedral Complexes Containing Optically Active Bidentat Lignd lik, pr:
‘An important example ofthis type of complex is (Caen) (pr) (NO2}21" in.
wire en CH CH
Il (ethylenediamine)
Nik Ni
ad pr) CH CHC Gropylensdiamne)
tu, |
N
‘The possible geometrical iomersof[Co{en) (pn) (NO )2]* ion are shown in Figure 2.35.
“There are two ci ine and only oe mans isomer, there are oly re geometical some
for {Co(et}(gn)(N0;)2)" ion, Since pr isan unsymmeti optical ative bidet gd, its doa
‘Neatoms ar diferent by marking one and two asterisks.
(Kt Potynncear Campleses:
The geomerical nome of dinuclear bridged octahedral compiex of Fe ), o
{Fe (OH) (HONG ae shown in Figure 2.36
a
x
s
e:
(XI) Oetahedral Complexes Containing Optically Active Bidentat Lignd lik, pr:
‘An important example ofthis type of complex is (Caen) (pr) (NO2}21" in.
wire en CH CH
Il (ethylenediamine)
Nik Ni
ad pr) CH CHC Gropylensdiamne)
tu, |
N
‘The possible geometrical iomersof[Co{en) (pn) (NO )2]* ion are shown in Figure 2.35.
“There are two ci ine and only oe mans isomer, there are oly re geometical some
for {Co(et}(gn)(N0;)2)" ion, Since pr isan unsymmeti optical ative bidet gd, its doa
‘Neatoms ar diferent by marking one and two asterisks.
(Kt Potynncear Campleses:
The geomerical nome of dinuclear bridged octahedral compiex of Fe ), o
{Fe (OH) (HONG ae shown in Figure 2.36
a
To Distinguish els- and trans-Isomers
‘The cis and trans: isomers can be distinguished by the following methods:
(® Dipole Moment Measurements: The rans- somes has dipole moments equal 0 zero because
dipole moment of one M-L bond is cancelled by the dipole moment of other M-L bond lying on the
side. In civisomers the dipole moments of to MEL bonds (which ae ci to one anther)
bute in the same direction resulting in a some value of dipole moment.
(©) Infrared Spectroscopy : In order for a molecle 10 sbsor ifared radiations to cause
ration, there must be change in the pole moment ofthe molecule sit vibrates. case of trans
complexes such s Pt (NH }2ClJandCo(NHS) Cla ]*, the Chmetl-Clsynmetic stretching causes
1 change in the dipole moment ofthe molecule (see Figure 237). Therefore, these two compounds are
inactive and ao band comesponding to symmeticstrching vibrations is observed inthe infrared
pecrum. Incase ofthe cis isomers ofthese complexes both he symmetic and asyaunetic stretching
batons of CrnetalCl bonds cause appreciable changes in dipole moment. Ths, these mode of
baton for ir complexes are IR active and there area mumber of bands in the infaed spectrum.
(ip Chemical Method : Grinberg’s Method
Val ah NE GHCOOH, COOH Nr
Coon
ithe nd es some pt, co forms ltt complete ande ans
ine om a noo-celated complex. The reactions ofr example, cr and ans PL(NH,) CI]
CO and 20100" at shown in Figure 238
see my,
rove: u ins
tonces
Figorez38,
nivel is bras one ol one ne ml CH 2COOH D COOH
coon
sand whereas for one mole of rans isomer two moles of either NACH, COOH or COOHis used.
|
coon
cis iomer forms chelate with chelating ligands because ho two donor atoms coordinate on adjacent
postions resulting in leas strain. But in case of ran isomer, the donor atom of chelating ligands can
not coordinate atthe rans- positions bacause of lrg strain. This lage stain causes the unstabiliy o
the chelated complex.
‘The cis and trans: isomers can be distinguished by the following methods:
(® Dipole Moment Measurements: The rans- somes has dipole moments equal 0 zero because
dipole moment of one M-L bond is cancelled by the dipole moment of other M-L bond lying on the
side. In civisomers the dipole moments of to MEL bonds (which ae ci to one anther)
bute in the same direction resulting in a some value of dipole moment.
(©) Infrared Spectroscopy : In order for a molecle 10 sbsor ifared radiations to cause
ration, there must be change in the pole moment ofthe molecule sit vibrates. case of trans
complexes such s Pt (NH }2ClJandCo(NHS) Cla ]*, the Chmetl-Clsynmetic stretching causes
1 change in the dipole moment ofthe molecule (see Figure 237). Therefore, these two compounds are
inactive and ao band comesponding to symmeticstrching vibrations is observed inthe infrared
pecrum. Incase ofthe cis isomers ofthese complexes both he symmetic and asyaunetic stretching
batons of CrnetalCl bonds cause appreciable changes in dipole moment. Ths, these mode of
baton for ir complexes are IR active and there area mumber of bands in the infaed spectrum.
(ip Chemical Method : Grinberg’s Method
Val ah NE GHCOOH, COOH Nr
Coon
ithe nd es some pt, co forms ltt complete ande ans
ine om a noo-celated complex. The reactions ofr example, cr and ans PL(NH,) CI]
CO and 20100" at shown in Figure 238
see my,
rove: u ins
tonces
Figorez38,
nivel is bras one ol one ne ml CH 2COOH D COOH
coon
sand whereas for one mole of rans isomer two moles of either NACH, COOH or COOHis used.
|
coon
cis iomer forms chelate with chelating ligands because ho two donor atoms coordinate on adjacent
postions resulting in leas strain. But in case of ran isomer, the donor atom of chelating ligands can
not coordinate atthe rans- positions bacause of lrg strain. This lage stain causes the unstabiliy o
the chelated complex.
LG Caton Ca,
(SI
‘Opal isomers or enantiomers are ais ofmoleuls rios whicharenon-superimpossble minor
images ofeach other The tera superinposle mans hat fone scr id over the other of he
same molecule, the poston ofl te atoms wil mc andthe tem.non-superrposable ans that if
oe structure is aid over the other ofthe seme molecal, he poions ofall the atoms vil not match. For
“example, ia pipeteis placed in front of a miro te image reflected is ideaical tothe pipewe itself. The
pipette and its miror image both are superimposable. Ifthe left hand is placed in front of à mirror, the
image flecos wil ook lic the righthand, Tus, can say hat ie ef kand and righthand are minor
image ofeach other, However, hey ae nor superimpoable because when left hand is placed over ight
Hand Keeping both palms down, they d oot mach. Te an superinpssble property of et and right
hands is cla handednes. The optical isomer have bandos and ae suid to chiral (pronounced
Fura, from the greek word, cheir, meaning hand) because lke left and sight hands, chiral molecules are
non siperimposable Isomers that ae suerimpoablo (Le, tt lak handedness) with ther minor
sages ar std to be non hir or achiral, Chiral males pica active because they rotate the
plane of plane poltized tight sit pass through he soon of tem. Uni rdiary ight, which
vibrates in all directions, plane polarized light vibrates only in single plane. Plane polarized light is
tained by passing ordinary ight through placing Oke iol pris) which is made up of quart,
‘Caf, When plane polarized Tigh i passed hr he soin of a chil compound the plane of
polarization i rotated either to the right orto the left. If the plane of polarization is rotated to right, the
isomer is said to be dextrorotatory (dor +), ifthe plane of potarization is rotated 10 left, the isomer is said.
tobelevortatory (r=). The d- and! isomersofachica substance sealed enaatiomers. The d- and
isomers oa the plane of polarized ligt y the equal amount bia opposite direction, An equimolar
mist of d= and = tomers, called a raceme mr pres no net optical rotation because the
cotton produced by the individual enantiomers is excl cancel,
The essa condition fora substance to be cial fr opti atv) is thatthe substance ha no
plage of pme. Ia substance has a plane oT Spey. en rl ci (or tal activo,
{The wbstinces having no plane of Same (Gr minor pe symmety) are Always
on-superinposableon thir minor images
¡OPTICAL ISOMERISM.IN SQUARE PLANAR COMPLEXE
Square planar complexes rarely show optical isomerism with al four igands ae different or
same because they have alt four ligands nthe metal ation the sume plane and bence havea plane
of symmetry. However, there are excepirally some complets whch exhibit optical isomerism, For
«sample, (Gobutylenediamire) (meso-dpheoyletylcocdimine) palladiam (I) or pistioum U)
complexes (also called as isobutyenediamine mesoslbeneiamin paldium (I) or platinum (I)
complexes) re square planar structures and re optical ave. The pial isomers of PI) or PA)
square planar complex ar shown in Figure 239
thylevedauineetreacetets, EDTA fome a square plana complex ion with alladium (1) à
ich BOTA acts a tad gd Te umge im xine opal er as va
Figure 240,
oo ecos Te “coca, oc, |
oh Cty cm | | oon, |
Tien | pie
ao oo 1 Lo Toco
Tetrabedral Completes:
Tetrahedral complexes of [Ma4]*, (Mezbz]" and (Masbj"* type do not show optical
isomerisn because all the possible arangemeis ofthe ligands round the meta cation are the same,
However, (Mabedj"* type teiuhedral complexes show optical isomerism. For example
[As (CH) (CH NSKCGlEsCOO)]” ion show optical isomers as shown in Figure 2.41
5
(SI
‘Opal isomers or enantiomers are ais ofmoleuls rios whicharenon-superimpossble minor
images ofeach other The tera superinposle mans hat fone scr id over the other of he
same molecule, the poston ofl te atoms wil mc andthe tem.non-superrposable ans that if
oe structure is aid over the other ofthe seme molecal, he poions ofall the atoms vil not match. For
“example, ia pipeteis placed in front of a miro te image reflected is ideaical tothe pipewe itself. The
pipette and its miror image both are superimposable. Ifthe left hand is placed in front of à mirror, the
image flecos wil ook lic the righthand, Tus, can say hat ie ef kand and righthand are minor
image ofeach other, However, hey ae nor superimpoable because when left hand is placed over ight
Hand Keeping both palms down, they d oot mach. Te an superinpssble property of et and right
hands is cla handednes. The optical isomer have bandos and ae suid to chiral (pronounced
Fura, from the greek word, cheir, meaning hand) because lke left and sight hands, chiral molecules are
non siperimposable Isomers that ae suerimpoablo (Le, tt lak handedness) with ther minor
sages ar std to be non hir or achiral, Chiral males pica active because they rotate the
plane of plane poltized tight sit pass through he soon of tem. Uni rdiary ight, which
vibrates in all directions, plane polarized light vibrates only in single plane. Plane polarized light is
tained by passing ordinary ight through placing Oke iol pris) which is made up of quart,
‘Caf, When plane polarized Tigh i passed hr he soin of a chil compound the plane of
polarization i rotated either to the right orto the left. If the plane of polarization is rotated to right, the
isomer is said to be dextrorotatory (dor +), ifthe plane of potarization is rotated 10 left, the isomer is said.
tobelevortatory (r=). The d- and! isomersofachica substance sealed enaatiomers. The d- and
isomers oa the plane of polarized ligt y the equal amount bia opposite direction, An equimolar
mist of d= and = tomers, called a raceme mr pres no net optical rotation because the
cotton produced by the individual enantiomers is excl cancel,
The essa condition fora substance to be cial fr opti atv) is thatthe substance ha no
plage of pme. Ia substance has a plane oT Spey. en rl ci (or tal activo,
{The wbstinces having no plane of Same (Gr minor pe symmety) are Always
on-superinposableon thir minor images
¡OPTICAL ISOMERISM.IN SQUARE PLANAR COMPLEXE
Square planar complexes rarely show optical isomerism with al four igands ae different or
same because they have alt four ligands nthe metal ation the sume plane and bence havea plane
of symmetry. However, there are excepirally some complets whch exhibit optical isomerism, For
«sample, (Gobutylenediamire) (meso-dpheoyletylcocdimine) palladiam (I) or pistioum U)
complexes (also called as isobutyenediamine mesoslbeneiamin paldium (I) or platinum (I)
complexes) re square planar structures and re optical ave. The pial isomers of PI) or PA)
square planar complex ar shown in Figure 239
thylevedauineetreacetets, EDTA fome a square plana complex ion with alladium (1) à
ich BOTA acts a tad gd Te umge im xine opal er as va
Figure 240,
oo ecos Te “coca, oc, |
oh Cty cm | | oon, |
Tien | pie
ao oo 1 Lo Toco
Tetrabedral Completes:
Tetrahedral complexes of [Ma4]*, (Mezbz]" and (Masbj"* type do not show optical
isomerisn because all the possible arangemeis ofthe ligands round the meta cation are the same,
However, (Mabedj"* type teiuhedral complexes show optical isomerism. For example
[As (CH) (CH NSKCGlEsCOO)]” ion show optical isomers as shown in Figure 2.41
5
— a +
“Telraheda! complexes of Be (1D, (aná Za (1) with unsyrumeti chelating Higand as exis as
| optical isomers. For example, optical isomers of bis (henzoylacetonato) beylium are shown in
Figure 242.
Co Sis
Se “4
pry, pats os, \ Va
a CE one ju on
Sl aE a No
FG N
of, os
Optical amer in Otahedral Completes:
ctahoiralcompenes ofthe pe of[Mag]"*,(Masbl*™ are optically inactive and do not show
onal isomerism became of he press of plane of symmery (ige 243) For empl,
(Co(Stts)g} and (Co(Nta Cons both have plane of symmetry and hence are opc
inactive. a
| nl
| git Din
| a
Otal mache
© Ma, ba]"* ype Compeses : An inporant example” dt Mis pe “of complex is
{Co(NHs)¢Cia]* ion which exis in i- and rans isomeric forms (Figure 2.44). Bok these om
me ol symmetry and clas are opi inactive Ths, his typeof complexes dont how
es oplealy nase
ns epi nacio
Gi) (Magbel"* type Complexes + An important example of this type of complexes is
LCOQNE3 4 (#,0}C1}* ion. This complexion exists in cis- and trans - forms (Figure 2.45) Both these
forms are achiral Therefore, these forms do pot show optical isomerism,
RUES
(Gi) (Mtayby]"* pe complexes : An important example of this pe of compleres is
(Co(NHs}sC13} This complex exists in facial (Le cs) and meridional (.e, mans) foms (Figure
2.46). Both these forms ar achial and optically inactive. Therefore, these forms do no show opal
‘meropteay mace
69) IMazbacıl"* type complexes : An important example of tis pe of complexes is
PQ (232.01? ion This complex ion exit in five geometria isomers, out ofthese only one
some exit seo opal sms which re mir image of eachother and are oonsperinposble
on eah other a showin Figure 247
“Telraheda! complexes of Be (1D, (aná Za (1) with unsyrumeti chelating Higand as exis as
| optical isomers. For example, optical isomers of bis (henzoylacetonato) beylium are shown in
Figure 242.
Co Sis
Se “4
pry, pats os, \ Va
a CE one ju on
Sl aE a No
FG N
of, os
Optical amer in Otahedral Completes:
ctahoiralcompenes ofthe pe of[Mag]"*,(Masbl*™ are optically inactive and do not show
onal isomerism became of he press of plane of symmery (ige 243) For empl,
(Co(Stts)g} and (Co(Nta Cons both have plane of symmetry and hence are opc
inactive. a
| nl
| git Din
| a
Otal mache
© Ma, ba]"* ype Compeses : An inporant example” dt Mis pe “of complex is
{Co(NHs)¢Cia]* ion which exis in i- and rans isomeric forms (Figure 2.44). Bok these om
me ol symmetry and clas are opi inactive Ths, his typeof complexes dont how
es oplealy nase
ns epi nacio
Gi) (Magbel"* type Complexes + An important example of this type of complexes is
LCOQNE3 4 (#,0}C1}* ion. This complexion exists in cis- and trans - forms (Figure 2.45) Both these
forms are achiral Therefore, these forms do pot show optical isomerism,
RUES
(Gi) (Mtayby]"* pe complexes : An important example of this pe of compleres is
(Co(NHs}sC13} This complex exists in facial (Le cs) and meridional (.e, mans) foms (Figure
2.46). Both these forms ar achial and optically inactive. Therefore, these forms do no show opal
‘meropteay mace
69) IMazbacıl"* type complexes : An important example of tis pe of complexes is
PQ (232.01? ion This complex ion exit in five geometria isomers, out ofthese only one
some exit seo opal sms which re mir image of eachother and are oonsperinposble
on eah other a showin Figure 247
{somes (e) and () ae the minor images (ie, enantiomers) ofeach other and ace optically active
Tsomer (©), (8, (e)and (Dare achiral and optically inactive and us these isomers o notexistasoptica
isomens.
(9) Mabedet)"* type Complexes:
EPL) (MSN ICH is the only complex of this type. The possible number of
¡someta some ofthis complex is 15. ach of these 15 geometrical isomers is chiral and he is
optically active. Therefore, there ae 15 pais of enantiomers total number of optical isomers 30),
‘The optical isomers of one ofthe LS geometrical isomers are shown in Figure 248,
RE mm
et asian ee pa
N,
7 by
ré
(HD IMCAA} I" type Complexes ;
Here (AA) is à symmetic bidentate ligand which may be citer a neta or negative ion. The |
examples ofthis pe of complexes are: {Co(en)s}°* ,{Ce(ox)s} et. each of which is chiral, Such
complexes can ein eter of to coationeri forms (Le, d-and comen) ora racemic mixture of
the vo. rito be nd tha an acta! complex containing three cheat ngs are always chiral nd
‘opically ative. Theo, these complexes are always exist as pis ofenctiomes Optical isomers of
Ces) and (Con) > ions are shown in Figure 2.9.
ro Dre ; rai =
Oe, { Lomo
rea lis vee
Tsomer (©), (8, (e)and (Dare achiral and optically inactive and us these isomers o notexistasoptica
isomens.
(9) Mabedet)"* type Complexes:
EPL) (MSN ICH is the only complex of this type. The possible number of
¡someta some ofthis complex is 15. ach of these 15 geometrical isomers is chiral and he is
optically active. Therefore, there ae 15 pais of enantiomers total number of optical isomers 30),
‘The optical isomers of one ofthe LS geometrical isomers are shown in Figure 248,
RE mm
et asian ee pa
N,
7 by
ré
(HD IMCAA} I" type Complexes ;
Here (AA) is à symmetic bidentate ligand which may be citer a neta or negative ion. The |
examples ofthis pe of complexes are: {Co(en)s}°* ,{Ce(ox)s} et. each of which is chiral, Such
complexes can ein eter of to coationeri forms (Le, d-and comen) ora racemic mixture of
the vo. rito be nd tha an acta! complex containing three cheat ngs are always chiral nd
‘opically ative. Theo, these complexes are always exist as pis ofenctiomes Optical isomers of
Ces) and (Con) > ions are shown in Figure 2.9.
ro Dre ; rai =
Oe, { Lomo
rea lis vee
NEA
Ee
(vi) (M(AA)242]"* type complexes : An important example ofthis ype of complexes is
| {Cte ion, This comple fon exis as ci and on ses, i isomers is chal and
| optically active, Thos, it exists as d- and /- isomers as shown in Figure 250. On the other hand, be
ransisomer is achiral and optically inactive, therefore, this trans isomer does not show optical
| ra y Ä =
MES
| =. | x
Otter examples of | (M(AA)za2]"*
[HC (COCHE D ee
type complexes ame: (en) (NO )2 1".
D (MCAA)2 aby" pe Complexes + An imporant example ofthis ype of complexes is
[Cofen)> (NH; JCI?* ion. This complex ion exist in es and trans forms. er isomer is chiral and
optically active. Therefore, tan be resolved into d-and isomers, The d- and - isomers are shown in
| Fswe 2, One other hand, theres nome child ptite Tees, he ans
isomer can not be resolved into d and I isomers
(ix) (MCAA}azb2{"* type-Complexes + Some examples of this ype of complexes are
ICo(en)(NHs)2C12]",(CO(C¿O, NH )2(NO2)21*,[Co(eokpy)2(Cl2]* et. These complex ions
show geometrical isomerism. The cis isomers are chiral and optically active. Therefore, these cis-
isomers canbe resolved into dard Lisomers. The ans isomers ar achiral and optically inactive and
al isomerism. The optica isomers MC (rs Cl in ar sh in
sans
Acta and opa rate
Acta opa race
SA
Ee
(vi) (M(AA)242]"* type complexes : An important example ofthis ype of complexes is
| {Cte ion, This comple fon exis as ci and on ses, i isomers is chal and
| optically active, Thos, it exists as d- and /- isomers as shown in Figure 250. On the other hand, be
ransisomer is achiral and optically inactive, therefore, this trans isomer does not show optical
| ra y Ä =
MES
| =. | x
Otter examples of | (M(AA)za2]"*
[HC (COCHE D ee
type complexes ame: (en) (NO )2 1".
D (MCAA)2 aby" pe Complexes + An imporant example ofthis ype of complexes is
[Cofen)> (NH; JCI?* ion. This complex ion exist in es and trans forms. er isomer is chiral and
optically active. Therefore, tan be resolved into d-and isomers, The d- and - isomers are shown in
| Fswe 2, One other hand, theres nome child ptite Tees, he ans
isomer can not be resolved into d and I isomers
(ix) (MCAA}azb2{"* type-Complexes + Some examples of this ype of complexes are
ICo(en)(NHs)2C12]",(CO(C¿O, NH )2(NO2)21*,[Co(eokpy)2(Cl2]* et. These complex ions
show geometrical isomerism. The cis isomers are chiral and optically active. Therefore, these cis-
isomers canbe resolved into dard Lisomers. The ans isomers ar achiral and optically inactive and
al isomerism. The optica isomers MC (rs Cl in ar sh in
sans
Acta and opa rate
Acta opa race
SA
Es (M(AB)1"* type Complexes: Animparat example this type of complexes isfCo (gs)
“This complex show geometric! isomerism and exstinfc- and mer-someric forms, Bot hes iors
are chiral and optically active. Therefore, bot these isomers fac- and mer) can be resoved into d- and
‘isomers. The optical isomers OF Ce) Jar shown in Figure 2.53,
CE
a
MES
Moor Lotion
(xi) M(AA)2(BB) type Complexes : Ax important example of this type of complexes is
{Cofen)2(60)" fon. This complex is neither is nor rans- at tas one optical isomer as shown in
Figure 2.54
5
LD
RAS
LK
(si) (M(AA)2(AB)I"* type Comptexes : This type of complexes do not show geometrical
‘isomerism but these ae chiral and optically active, Therefore, these complexes can exist ind and I
isomeric forms as shown in Figure 255.
>
i) IM(AANAB)2]"* type Complexe
andl geomotice! isomers ar chiral nd oúcly ative. Therefore, a the geometricl isomers can
cist in d and J forms as shown in Figure 2.56.
peers)
“This complex show geometric! isomerism and exstinfc- and mer-someric forms, Bot hes iors
are chiral and optically active. Therefore, bot these isomers fac- and mer) can be resoved into d- and
‘isomers. The optical isomers OF Ce) Jar shown in Figure 2.53,
CE
a
MES
Moor Lotion
(xi) M(AA)2(BB) type Complexes : Ax important example of this type of complexes is
{Cofen)2(60)" fon. This complex is neither is nor rans- at tas one optical isomer as shown in
Figure 2.54
5
LD
RAS
LK
(si) (M(AA)2(AB)I"* type Comptexes : This type of complexes do not show geometrical
‘isomerism but these ae chiral and optically active, Therefore, these complexes can exist ind and I
isomeric forms as shown in Figure 255.
>
i) IM(AANAB)2]"* type Complexe
andl geomotice! isomers ar chiral nd oúcly ative. Therefore, a the geometricl isomers can
cist in d and J forms as shown in Figure 2.56.
peers)
LEASE BC SRE EEE TEE ae
(xiv) Octahedeal Complexes Containing Optically Active Ligand } (ev) Oetahedral Complexes Containing Polydentate Ligands such as EDTAC: The important
‘An important example of this type of complexes is [Co(en)(pn}(NOz)2]* ion. This complex ion
exists two cis-and one ans- isomers, each of thes isomers is chiral and optically active Therefore,
‘the cisisemers ext ind and iso forms (Figure 2.57). On he other hand, the rr-isomer has
plane of symmetry and therefore, should be achiral and optically inactive but is some hs optically
active ligand (pr) Thus, it would be optically active
AON N ;
FA
LE
esos
examples of this type of complexes are :[CA(EDTA)]”, (Mg (EDTAJ]”, [Co(EDTAM ete. These
complexes ae ner cis-nar ran but he are ciel nd optically active Teror, Bey rit de
and f-isomers. The d- and Lisomers of [CO(EDTA)]” are shown in Figure 2.58.
(evi) Bridged Binuclear Octahedral Complexes (Le, Polyuuclear Compleses) : Optical
‘isomerism sat limited to monoauclea complexes. Polynuclear complexes containing brigingignds
can also exist as and isomers. For example, the binuclear Co * complexion shown in Figure 2.59.
exist scis-and tran-isomers. The cis-isomers ischial and optically active and thus exists 6 and
isomers as shown in Figure 2.60. The uns isomer is achiral and inactive and thus his isomer is an
intemally optically compensated ie, itis meso form,
a
LS
en;co: Cofen}
| ig AA
(xiv) Octahedeal Complexes Containing Optically Active Ligand } (ev) Oetahedral Complexes Containing Polydentate Ligands such as EDTAC: The important
‘An important example of this type of complexes is [Co(en)(pn}(NOz)2]* ion. This complex ion
exists two cis-and one ans- isomers, each of thes isomers is chiral and optically active Therefore,
‘the cisisemers ext ind and iso forms (Figure 2.57). On he other hand, the rr-isomer has
plane of symmetry and therefore, should be achiral and optically inactive but is some hs optically
active ligand (pr) Thus, it would be optically active
AON N ;
FA
LE
esos
examples of this type of complexes are :[CA(EDTA)]”, (Mg (EDTAJ]”, [Co(EDTAM ete. These
complexes ae ner cis-nar ran but he are ciel nd optically active Teror, Bey rit de
and f-isomers. The d- and Lisomers of [CO(EDTA)]” are shown in Figure 2.58.
(evi) Bridged Binuclear Octahedral Complexes (Le, Polyuuclear Compleses) : Optical
‘isomerism sat limited to monoauclea complexes. Polynuclear complexes containing brigingignds
can also exist as and isomers. For example, the binuclear Co * complexion shown in Figure 2.59.
exist scis-and tran-isomers. The cis-isomers ischial and optically active and thus exists 6 and
isomers as shown in Figure 2.60. The uns isomer is achiral and inactive and thus his isomer is an
intemally optically compensated ie, itis meso form,
a
LS
en;co: Cofen}
| ig AA
1. The NOF ligand cam form... iSOmENS,
2. The comple cis4Co(en)s (NH YC1}** can exists.
3. The complet (Co(N AC J° can exist 88 o SOME
4, The comples {CNH JaCKNO» )] Br can exist as scl isomers as
tomes
5. The complex (Co(EDTAIT isa ….
6. cis{Cofen}2Clo]* is optical
7. Chirali sth essential condition fr nun
8. The complex (QXNH3}3(NO2)s show two geomerical isomers namely.
fans. Lo linkage 2. enantiomers
3. geometria! 4. Ykage, onen "À
5. chelate 6 acive
7. optical getty 3. facia, meidonal y
ve Questions
+f) Namco seiisamers fe compound (Co(WH)sCIaBr fare Mabe
a 62 ao 7
F CE ws a
mn 2. The complees (CCI diaminopropane Ca J* and [Co 1,3-tiaminopopanc)Ch]* represent
A empleo
1 D an Gone (6) linkage isomerism
8 | 6 rien somes @ coordination isomerism
(Se mune of posite men forthe octane complex fon [Co ChBr
al a2 ws w ma
os (98 >
44 Foraconpe, MX, pos gona primate geomet the runkerofposihlesomen is
@2 4
y Yes (os
Whe number of posible general isomers for octahedral Cox) (PME NHS Chis:
w2 CE
@47 @s
2. The comple cis4Co(en)s (NH YC1}** can exists.
3. The complet (Co(N AC J° can exist 88 o SOME
4, The comples {CNH JaCKNO» )] Br can exist as scl isomers as
tomes
5. The complex (Co(EDTAIT isa ….
6. cis{Cofen}2Clo]* is optical
7. Chirali sth essential condition fr nun
8. The complex (QXNH3}3(NO2)s show two geomerical isomers namely.
fans. Lo linkage 2. enantiomers
3. geometria! 4. Ykage, onen "À
5. chelate 6 acive
7. optical getty 3. facia, meidonal y
ve Questions
+f) Namco seiisamers fe compound (Co(WH)sCIaBr fare Mabe
a 62 ao 7
F CE ws a
mn 2. The complees (CCI diaminopropane Ca J* and [Co 1,3-tiaminopopanc)Ch]* represent
A empleo
1 D an Gone (6) linkage isomerism
8 | 6 rien somes @ coordination isomerism
(Se mune of posite men forthe octane complex fon [Co ChBr
al a2 ws w ma
os (98 >
44 Foraconpe, MX, pos gona primate geomet the runkerofposihlesomen is
@2 4
y Yes (os
Whe number of posible general isomers for octahedral Cox) (PME NHS Chis:
w2 CE
@47 @s
| oe
FERIA Cation Chem Siena Mail Cabin Conti"
€ existence of to diferent coloured complexes of CN «Clyde to 17. The complex het exits as a pair ofenantiomen is:
(8) optical isomerism ©) lintage isomerism = (6) ;rans- (Co(H1¿NCHCH2NH2)¿Cl23%
(© geometrical onessms (9) eooniaon omer asc Clg
The ee the Coflll) complexes Besen and © feeb KCIKBALCHS Jr
(a) orton and postion" (@) optical end Linkage yr (0 (OP NCHCHZNH D
(© gcomencal and linkage“ (@) optical and optical Sn ru of ose isomers fn bn a 9 2,.2- ini)
8. The complexes [Co(NH3)a(H120JC1] Br and [OH )4BrzJOLH3Oare examples of: 2 BI wa
(@ ionization isomerism (0) linkage homer à 64 (05
(©) geometie isomerism € optical isomerism 19. Thenumberof possible isomers forthe square planar mononuclear complex {(NHis )2 M(CN}2]of
he pfs a ast common ms cms id cin mer 2: ]_ seul Mi:
(a) Cá (iD and Hg) €) Cu (I) and Hg () 4° / 2 0
OD aná Hg (D ADAM 9 os @3
1 The octahedral complex/complex jon which shows Bft fädil and meridional isomers is 20, Green coloured Ni(PPh¿E0) Bra, has a magnetic moment of 3.20 B.M. The geometry and the
__ a) igscinatoeobal{) (D) tis ethylenediamine cobalUD) , 54. number of isomers possible forthe complex respectively, are
“(e dicrodigyleintocobal{) (4) oxsatoobale(M) \ (9 square plana and one arabe nd ne
15. Which one ofthe following compounds has opi gomers? (© square placa and to da) mabel ai wo
(0) rars{Cofen)2Cha} (en = ihylenedianie) ‘Te oll unter of seioisomers off aCl(NO)3 > = €
GC QE | 027 ws /
(0 Cata y = 2x os ws wy
Fan -CsHs)2] 22, Among he folowing complexes \ +
Hz, The complex [P:CINCSIONH)2 is capable of exhibiting eo [Riedy 57" - ary
(ais ions Di mms GED fu
(e) coordination isomerism optical somera >
3. The complexes [OuN 3), (PC, Jard (PANES) OACI as an example of Ne re
16) ionization isomerism (0) inkage isomerism (6 eis {CaCl (oxalato)? | on
(©) coordination isomerism (4) geometric isomeric the chiral complexes dre ” £ f
Ko) comple of Ni, (NICH, (Ph) ] is paramagnie, The aalogos PA) complex is AD, GG) OOO TS
diemagnete. Theme of isomers tt wiles fortheickel and the palladium compleses re © 6.6.6) OO. >
(2) one, one Gone Le, / \
(©) 40, one CES Ni
‘The numberof isomers that exists for{Mo(CsHsN)(CO)sJis:
(a) one (b) two:
ie Ope a #7 ¡P__——— |
The complex (Co(NH3)s (NOz)]?* is capable of exhibit
LO 219 38 40 50 6 26
€) optical isomerism €) geometia isomerism EG 20 00 LO na BA 10
(e) iniraionisamerism (E) linkage isomerism 4 Ko o no HH 2.0 BH HO
a
Jt
FERIA Cation Chem Siena Mail Cabin Conti"
€ existence of to diferent coloured complexes of CN «Clyde to 17. The complex het exits as a pair ofenantiomen is:
(8) optical isomerism ©) lintage isomerism = (6) ;rans- (Co(H1¿NCHCH2NH2)¿Cl23%
(© geometrical onessms (9) eooniaon omer asc Clg
The ee the Coflll) complexes Besen and © feeb KCIKBALCHS Jr
(a) orton and postion" (@) optical end Linkage yr (0 (OP NCHCHZNH D
(© gcomencal and linkage“ (@) optical and optical Sn ru of ose isomers fn bn a 9 2,.2- ini)
8. The complexes [Co(NH3)a(H120JC1] Br and [OH )4BrzJOLH3Oare examples of: 2 BI wa
(@ ionization isomerism (0) linkage homer à 64 (05
(©) geometie isomerism € optical isomerism 19. Thenumberof possible isomers forthe square planar mononuclear complex {(NHis )2 M(CN}2]of
he pfs a ast common ms cms id cin mer 2: ]_ seul Mi:
(a) Cá (iD and Hg) €) Cu (I) and Hg () 4° / 2 0
OD aná Hg (D ADAM 9 os @3
1 The octahedral complex/complex jon which shows Bft fädil and meridional isomers is 20, Green coloured Ni(PPh¿E0) Bra, has a magnetic moment of 3.20 B.M. The geometry and the
__ a) igscinatoeobal{) (D) tis ethylenediamine cobalUD) , 54. number of isomers possible forthe complex respectively, are
“(e dicrodigyleintocobal{) (4) oxsatoobale(M) \ (9 square plana and one arabe nd ne
15. Which one ofthe following compounds has opi gomers? (© square placa and to da) mabel ai wo
(0) rars{Cofen)2Cha} (en = ihylenedianie) ‘Te oll unter of seioisomers off aCl(NO)3 > = €
GC QE | 027 ws /
(0 Cata y = 2x os ws wy
Fan -CsHs)2] 22, Among he folowing complexes \ +
Hz, The complex [P:CINCSIONH)2 is capable of exhibiting eo [Riedy 57" - ary
(ais ions Di mms GED fu
(e) coordination isomerism optical somera >
3. The complexes [OuN 3), (PC, Jard (PANES) OACI as an example of Ne re
16) ionization isomerism (0) inkage isomerism (6 eis {CaCl (oxalato)? | on
(©) coordination isomerism (4) geometric isomeric the chiral complexes dre ” £ f
Ko) comple of Ni, (NICH, (Ph) ] is paramagnie, The aalogos PA) complex is AD, GG) OOO TS
diemagnete. Theme of isomers tt wiles fortheickel and the palladium compleses re © 6.6.6) OO. >
(2) one, one Gone Le, / \
(©) 40, one CES Ni
‘The numberof isomers that exists for{Mo(CsHsN)(CO)sJis:
(a) one (b) two:
ie Ope a #7 ¡P__——— |
The complex (Co(NH3)s (NOz)]?* is capable of exhibit
LO 219 38 40 50 6 26
€) optical isomerism €) geometia isomerism EG 20 00 LO na BA 10
(e) iniraionisamerism (E) linkage isomerism 4 Ko o no HH 2.0 BH HO
a
Jt
m
NB (PEIPh 7) has been isolated in green and brown species. Identify the two species,
2. Give one example ofeach ofthe following
(a) Ionization isomerism
(6) Linkage isomerism
(© Coordination posit
65 Hyde isomerism
(9 Coordination isomerism,
isomerism (D Ligand isomerism
. Sketch ll possible isomers of (Co{NHis)2 NE )2(C304)I” ion. Lable the isomers according to
the type ofisomersm.
1 A compound {Co(et)»(NOz)2 CI exists in the isomeric forms (A), (B) and (C). (A) reacts
‘neither with AGNO; nor with e ands optically inactive. (B) ceaots with AgNO and forms white
precipitate but not reacts with en ad is optically inactive. (C is optically active and reacts with
both AgNOs and en, Identity each isomer, draw their structures and give suitable reasons for your
5. Symmetrical di4chydroxotetrukiehylenediaminekicoblat(il) chloride (A) reacts wit aq, HCL
to gives product o(en) Cis (B) whichis resolvable with optical isomers, When tiskeptin acidic
solution, the compound changes colour and gives an isomer (C) which is not resolvable. Give
structure of A, B and C and alo write the optical isomers of.
Isitpossible to separate the optical isomers ofa neutral complex by forming diasteiomers?
Describe the type of isomers associated with exrbonatoaquatetraminecobalt(I}) chloride
monohydrate.
A 4 coordinated complex [MA B; Jess in two isomeric forms I and IL. has a dipole moment of
{6.00 units and I 20.1 D, Draw the structures of [and I
Indicate the typeof isomeris exhibited bythe following pis of isomers and suggest one tes for
each set to distinguish them.
ITCHNH3)6][Co(NO2)e Jen (Co; )JIC(NO Je]
@){Co(H20)sCIICI2 -H20 and [Co(H O4 CH 1CI-2H20
What type of isomers are shown by (Co(NHy Js (NOz)]Cland draw their structures?
Draw all the possible geometrical and optical isomers fo the following complexes:
AN] CAM Pc
(e) [Co(dienkNO2)33 (@){Co(dien)2)*
© Pten):CBr BR
For the [Cofen)2 (NO; SCNIJ" ion
(2) Draw all he possible stuctaal somes.
(6) Draw all the possible sterioisomen,
(e) Estimate he total numberof isomers (Structural + striisomes).
goo
try (URAC) for
‘naming of coordination compounds areas follows
1. Ifa coordination compound is ionic (ie, the coordination compound contains eithet a complex
cation or complex anion or both), the cation is named fist followed by the anion and the cation is
separated by a space from the anion, justas in other simple salts, No space is used within the name
‘of the complex ion. For example, in Ka(Fo(CN)5] and [CofNH3)5JCla the cations K and
ICONE) D are named, first followed by the mames of anions (Fe(CN)gJ* and CI"
respectively.
2. Ifa coordination compound is neunl,thename of compourd is written as one word (ke, the mame
of neutral complex compourd is given without space).
3. In the name of a complex ion or non-ionic complex, the ligands are named first but in alphabetical
‘order before the name ofthe metal ion cratom. The numeral prefixes such as di, tr, tetra ete. which
indicate the number of ligands ofa particular type are ignored in determining the orde
4. Oxidation number of meal cation or atom is written in Roman numeral in parentheses immediately
following the name of the meta. There is no space between the name of metal and parentheses.
5. Ifthe complex ion or neutral complex contains more than one ligand of a particular kind, the Greek
peefixes di, ti, tetra, penta, bexa- and so forth are used for 2, 3,4, 5, 6 and so forth respectively
6. I the name of the figand itself contains a Greek prefix, its name is put in parentheses and the
prefines bis, rs, tetrakis, pentaks, hexakis, heptakis ae used for 2, 3, 4, 5,6 and 7 respectively to
specify the number of ligands. For example, the figand ethylenediamine already contains di,
therefore, iftwo or three such ligands are present in a complex, the name is bis (ethylenediamine) or
tris (ethylenediamine),
7. The prefixes bis, is, tetrakis and so fob are also used for complex ligands, For example, io
CH NH; ligands ace present in a complex, the prefix bis-is used, Thus the name ofthe ligand is bis
(wethylamine). If we name it as dimelhylamine, we are referring to the following compound
a Noah
a
Dee
NB (PEIPh 7) has been isolated in green and brown species. Identify the two species,
2. Give one example ofeach ofthe following
(a) Ionization isomerism
(6) Linkage isomerism
(© Coordination posit
65 Hyde isomerism
(9 Coordination isomerism,
isomerism (D Ligand isomerism
. Sketch ll possible isomers of (Co{NHis)2 NE )2(C304)I” ion. Lable the isomers according to
the type ofisomersm.
1 A compound {Co(et)»(NOz)2 CI exists in the isomeric forms (A), (B) and (C). (A) reacts
‘neither with AGNO; nor with e ands optically inactive. (B) ceaots with AgNO and forms white
precipitate but not reacts with en ad is optically inactive. (C is optically active and reacts with
both AgNOs and en, Identity each isomer, draw their structures and give suitable reasons for your
5. Symmetrical di4chydroxotetrukiehylenediaminekicoblat(il) chloride (A) reacts wit aq, HCL
to gives product o(en) Cis (B) whichis resolvable with optical isomers, When tiskeptin acidic
solution, the compound changes colour and gives an isomer (C) which is not resolvable. Give
structure of A, B and C and alo write the optical isomers of.
Isitpossible to separate the optical isomers ofa neutral complex by forming diasteiomers?
Describe the type of isomers associated with exrbonatoaquatetraminecobalt(I}) chloride
monohydrate.
A 4 coordinated complex [MA B; Jess in two isomeric forms I and IL. has a dipole moment of
{6.00 units and I 20.1 D, Draw the structures of [and I
Indicate the typeof isomeris exhibited bythe following pis of isomers and suggest one tes for
each set to distinguish them.
ITCHNH3)6][Co(NO2)e Jen (Co; )JIC(NO Je]
@){Co(H20)sCIICI2 -H20 and [Co(H O4 CH 1CI-2H20
What type of isomers are shown by (Co(NHy Js (NOz)]Cland draw their structures?
Draw all the possible geometrical and optical isomers fo the following complexes:
AN] CAM Pc
(e) [Co(dienkNO2)33 (@){Co(dien)2)*
© Pten):CBr BR
For the [Cofen)2 (NO; SCNIJ" ion
(2) Draw all he possible stuctaal somes.
(6) Draw all the possible sterioisomen,
(e) Estimate he total numberof isomers (Structural + striisomes).
goo
try (URAC) for
‘naming of coordination compounds areas follows
1. Ifa coordination compound is ionic (ie, the coordination compound contains eithet a complex
cation or complex anion or both), the cation is named fist followed by the anion and the cation is
separated by a space from the anion, justas in other simple salts, No space is used within the name
‘of the complex ion. For example, in Ka(Fo(CN)5] and [CofNH3)5JCla the cations K and
ICONE) D are named, first followed by the mames of anions (Fe(CN)gJ* and CI"
respectively.
2. Ifa coordination compound is neunl,thename of compourd is written as one word (ke, the mame
of neutral complex compourd is given without space).
3. In the name of a complex ion or non-ionic complex, the ligands are named first but in alphabetical
‘order before the name ofthe metal ion cratom. The numeral prefixes such as di, tr, tetra ete. which
indicate the number of ligands ofa particular type are ignored in determining the orde
4. Oxidation number of meal cation or atom is written in Roman numeral in parentheses immediately
following the name of the meta. There is no space between the name of metal and parentheses.
5. Ifthe complex ion or neutral complex contains more than one ligand of a particular kind, the Greek
peefixes di, ti, tetra, penta, bexa- and so forth are used for 2, 3,4, 5, 6 and so forth respectively
6. I the name of the figand itself contains a Greek prefix, its name is put in parentheses and the
prefines bis, rs, tetrakis, pentaks, hexakis, heptakis ae used for 2, 3, 4, 5,6 and 7 respectively to
specify the number of ligands. For example, the figand ethylenediamine already contains di,
therefore, iftwo or three such ligands are present in a complex, the name is bis (ethylenediamine) or
tris (ethylenediamine),
7. The prefixes bis, is, tetrakis and so fob are also used for complex ligands, For example, io
CH NH; ligands ace present in a complex, the prefix bis-is used, Thus the name ofthe ligand is bis
(wethylamine). If we name it as dimelhylamine, we are referring to the following compound
a Noah
a
Dee
EA
endings ide 10-0, ite to ito ad at toto. But according to latest IUPAC convenson, ll tb
anionic ligands names are obline by eplacing the las eier e by.
| Pe
| 4, The names ano tins cad with the ero They are usa ci y hno eon
| ar o
“The names of anionic igands are given in Table 1.
1m cas ambiente gud, atom which Bande o sh meta cation specified by pacing
the symbol of the bonded atom after he name ofthe igand separated by hyphen. These ligands are abo
| given specific names foreach mode of attachment. Some examples are given below
Name and Mode of Attachmont of Ambidentate Ligands
TASA
no; | =O, nto Nornire
| | ono”, to orne
sar
| -SCN”, thieyanato - S or thicyanato
| NCS" into orion
some ligands which are given special names.
EEES
| E ue
dinitrogen
doxygen
pridine
| sr
CHINE meylamine
| (CHEN dimethylamine
Nito — Mia hydrazine
MECO we
MEN Aion
CH} )280,DMSO dimethylsulphoxide
Ga Rai or menée
E a
BC, ttichlorophosphine
Ligands having special names:
Nits | ammine
co carbonyl
cs thiocarbony!
#0 aqua
NO ritresyl
9. The vowel ending the numeral prefix ofthe ligands will not be ignored while writing the name. For
‘example, if there ae four NE, and two oxide ligands, then these are named as tetrameine and
trioxide respectively. Mono is an exception, mono + oxide -> monoxide.
10. Fora complex cation or neutral complex, the usual name ofthe metal is used the complex ian
anion, the ending ae ether ads to tbe name of metal or replaces iu, -enor - es ending.
Name of meti obtained by replacing ending - ium by - at.
12,537 Raton Name
aluminium | ‘aluminate
‘scandium | scandate
vanadium | vanadate
zirconium | zirconate
oa | Sie
rhodium | rhodate
eu
endings ide 10-0, ite to ito ad at toto. But according to latest IUPAC convenson, ll tb
anionic ligands names are obline by eplacing the las eier e by.
| Pe
| 4, The names ano tins cad with the ero They are usa ci y hno eon
| ar o
“The names of anionic igands are given in Table 1.
1m cas ambiente gud, atom which Bande o sh meta cation specified by pacing
the symbol of the bonded atom after he name ofthe igand separated by hyphen. These ligands are abo
| given specific names foreach mode of attachment. Some examples are given below
Name and Mode of Attachmont of Ambidentate Ligands
TASA
no; | =O, nto Nornire
| | ono”, to orne
sar
| -SCN”, thieyanato - S or thicyanato
| NCS" into orion
some ligands which are given special names.
EEES
| E ue
dinitrogen
doxygen
pridine
| sr
CHINE meylamine
| (CHEN dimethylamine
Nito — Mia hydrazine
MECO we
MEN Aion
CH} )280,DMSO dimethylsulphoxide
Ga Rai or menée
E a
BC, ttichlorophosphine
Ligands having special names:
Nits | ammine
co carbonyl
cs thiocarbony!
#0 aqua
NO ritresyl
9. The vowel ending the numeral prefix ofthe ligands will not be ignored while writing the name. For
‘example, if there ae four NE, and two oxide ligands, then these are named as tetrameine and
trioxide respectively. Mono is an exception, mono + oxide -> monoxide.
10. Fora complex cation or neutral complex, the usual name ofthe metal is used the complex ian
anion, the ending ae ether ads to tbe name of metal or replaces iu, -enor - es ending.
Name of meti obtained by replacing ending - ium by - at.
12,537 Raton Name
aluminium | ‘aluminate
‘scandium | scandate
vanadium | vanadate
zirconium | zirconate
oa | Sie
rhodium | rhodate
eu
A Capote E f
{cats} NOAA teraaminecbloroniootl (ID chlide
oR
tereaminesbordoriio-N ba (I) horde
(PUN) (NCH ICC diamminechloromethylamine platinum (I) chloride
[Ru(NH3)s (N2)1C1> pentaamuminedinitrogenruthenium (II) chloride
{Cosi }5(604)]C penteemminesuphaoccba (code
[Cott )s CASOS pentaamninecorocbal (UD spe
num ana {Cots )s(ONO)SO4 eatzamuninnivit-O col (D pate
ungen tungstate {FLO (OJO, entaguanitesylzon (sulphate
nobbienum sobre Magnetic moment measurements how dat in complexes of roc, NO e peer +1 oxidation
Name of metals originated from Latin name =
stat, Therefore oxidation state of Fein {Fe( E20) (NOM is + 1.
Coordination Compounds Containing Complex Anion
Naz [fCN)s NO) sedimpentacyaronirsylerate (ID. As sua ari that in complexes
of iron, NO exists in + | oxidation state. Oxidation state of ion in Naz (FCN) s(NO}] is + 2 as
calculate below, Lethe oxidation number of Fe is x. Then
+12 ret 1xs)+1=0
wea?
Nas(i(c(604) BHO} sodiumaguadibonoeyene
EN PS amine plate)
RC) potassium teazidocobalte)
"he rule given above are ilusteated by the following examples CP calcium bocooplsptale{V)
(e) Non-inicr Neutral Complexes: Feres iron hexacynoferaeo)
LCR) Ch] iamminetichorocobl) RUN VOR] tetramethyl
Koi) 8021] ommineiirecheldi) texachloroxovanedatV)
or NAPBCIONO NTS sodium ammincromeehlvonrie-N
amet -N cobalt) patate)
(RAS), (NCS)a] «comaineniothiocarathodiom1) KICOEDTA] poison ehylendiamiteiacee
oR Le se © cobs
riemminetrilhioyanato - N rhodium(I) " h K2[CU(CM)2(0), (02 XNHy)] potassium acminedicyanodixoperoxo
NC) tetracarbonyickl (0) Etromate(V
FelCatis)> bis(eylopentadieny) ea) Kaas] potassium penachlcnirihosnae(V)
RRCRUANEH] dichloro bis (methylamine expe) {PheAshPCt (CI) teraphenylasonian
(CáCetl)a] bie benzene) womit) icone)
(= ON) Actor bs (tea) copper) ‘Naming of Bridged Polynuctear Complexes
19) Complexes Containing Complex Cations Aland tht ages wo mel cations or atoms is denoted by pts waded tthe ame ofthe
¿Coty JO hexzammilecobali(t chloe din ligands For example
LGV) ICI pestaanminechlrocbat(t chee (si) scr —-0-—Crsta)5}*" x
LC (HO) Cts (erzamırindiaquacba() code Ce nee Ro ©
er exakt (eet ioc) kn) clio OR pentane ch (U hope taie chona I)
Ron tris (hylendianine ob) boite oO e debates
{cats} NOAA teraaminecbloroniootl (ID chlide
oR
tereaminesbordoriio-N ba (I) horde
(PUN) (NCH ICC diamminechloromethylamine platinum (I) chloride
[Ru(NH3)s (N2)1C1> pentaamuminedinitrogenruthenium (II) chloride
{Cosi }5(604)]C penteemminesuphaoccba (code
[Cott )s CASOS pentaamninecorocbal (UD spe
num ana {Cots )s(ONO)SO4 eatzamuninnivit-O col (D pate
ungen tungstate {FLO (OJO, entaguanitesylzon (sulphate
nobbienum sobre Magnetic moment measurements how dat in complexes of roc, NO e peer +1 oxidation
Name of metals originated from Latin name =
stat, Therefore oxidation state of Fein {Fe( E20) (NOM is + 1.
Coordination Compounds Containing Complex Anion
Naz [fCN)s NO) sedimpentacyaronirsylerate (ID. As sua ari that in complexes
of iron, NO exists in + | oxidation state. Oxidation state of ion in Naz (FCN) s(NO}] is + 2 as
calculate below, Lethe oxidation number of Fe is x. Then
+12 ret 1xs)+1=0
wea?
Nas(i(c(604) BHO} sodiumaguadibonoeyene
EN PS amine plate)
RC) potassium teazidocobalte)
"he rule given above are ilusteated by the following examples CP calcium bocooplsptale{V)
(e) Non-inicr Neutral Complexes: Feres iron hexacynoferaeo)
LCR) Ch] iamminetichorocobl) RUN VOR] tetramethyl
Koi) 8021] ommineiirecheldi) texachloroxovanedatV)
or NAPBCIONO NTS sodium ammincromeehlvonrie-N
amet -N cobalt) patate)
(RAS), (NCS)a] «comaineniothiocarathodiom1) KICOEDTA] poison ehylendiamiteiacee
oR Le se © cobs
riemminetrilhioyanato - N rhodium(I) " h K2[CU(CM)2(0), (02 XNHy)] potassium acminedicyanodixoperoxo
NC) tetracarbonyickl (0) Etromate(V
FelCatis)> bis(eylopentadieny) ea) Kaas] potassium penachlcnirihosnae(V)
RRCRUANEH] dichloro bis (methylamine expe) {PheAshPCt (CI) teraphenylasonian
(CáCetl)a] bie benzene) womit) icone)
(= ON) Actor bs (tea) copper) ‘Naming of Bridged Polynuctear Complexes
19) Complexes Containing Complex Cations Aland tht ages wo mel cations or atoms is denoted by pts waded tthe ame ofthe
¿Coty JO hexzammilecobali(t chloe din ligands For example
LGV) ICI pestaanminechlrocbat(t chee (si) scr —-0-—Crsta)5}*" x
LC (HO) Cts (erzamırindiaquacba() code Ce nee Ro ©
er exakt (eet ioc) kn) clio OR pentane ch (U hope taie chona I)
Ron tris (hylendianine ob) boite oO e debates
fa complex ha, (wo, three or four bridging ligando of same nd then the refer di, ri peur
ware used respestivly, Fac example
a
[CA Lo la
di chloro bis [éfammine platinum (1) Chloride
‘OR diammine platinum (1) - di choro diammine platinum QU) chloride
If a complex has two or more different Kind of ligands, then prefix is used for each kind of
‘bridging ligand. The name of bridging ligands are writen in the alphabetca order. For example
i ges po
o EL, out
AM amido == hydroxo Bf tetranmainecobalt (IM)
OR tetrzmmine cobalt (I) >= arido- 4 hydronotetraummine cobalt (I)
OR amido =p hydroxocetamminedicobat (UD.
2 Nito
& [CNT TT TA
No, 7"
u - amido - 1 - superoxo his | tetraamminecobalt (IIT)]
on IK amido -- sopernooctsmarneicobalt UD,
OR tirammine cobalt (U) amd -syperooteatmmine cobal (I)
Fortis complexion, nagneie moment ei Oz ende
prod)
te ting dh teri (u ig Bars an il, be
ligands are named first. For example EN
co
Core <> Foo),
tii carbon bis (ricarbonylirofO)]
e. ti ue carbonyl nexacarbonylizon(0)
Ite bridging ligand bridges more than two metal centres, pre ele used o indicate the
number of metal centres bridged with a given ligand. For exaipe, in basic berytium eciat,
[Be10(CH:C00)1,0* ligand bridges four Be atoms. Therefor, he name ofthis compound is
4.010 hexa- -aceao tetrberfium (1)
‘The structure of basic heryium acetates shown in Figure 3.1
Hye
Rene 3 Lire ai oups OS
Same ote examples of ridged poynucear completes ar how below
o [HN sCo—NHs — CAN (OIC
Ramin cosa) > mido taria quo) chloride
Nt
@ A yay
KO
amido - ja nitro bisfteraammine cobalt]
OR amido - y-itro octemminediccbalQl)
OR tetraammine cobalt (11) --emido- proto termmine cobalt)
NE
AR
CONTI Cat cr
0
eamido- p=soperoxo bis [riamuninechoracaa!
NB
w ¡A Co LC 2G”
CE
ttammine cobalt amido - upon ianminsichloe col)
Note: A symmetrie bridged dinuclear complex, can be named by any three methods as shown
ess in examples (), (i) and (i) ut an unsymmer complex can be named by only one method as
given in example (iv)
a
0) [(SnCI3)2 RA) RSC) JA
Sa 5
ie u-chlorobisrichlorostanylhodan(t]
ware used respestivly, Fac example
a
[CA Lo la
di chloro bis [éfammine platinum (1) Chloride
‘OR diammine platinum (1) - di choro diammine platinum QU) chloride
If a complex has two or more different Kind of ligands, then prefix is used for each kind of
‘bridging ligand. The name of bridging ligands are writen in the alphabetca order. For example
i ges po
o EL, out
AM amido == hydroxo Bf tetranmainecobalt (IM)
OR tetrzmmine cobalt (I) >= arido- 4 hydronotetraummine cobalt (I)
OR amido =p hydroxocetamminedicobat (UD.
2 Nito
& [CNT TT TA
No, 7"
u - amido - 1 - superoxo his | tetraamminecobalt (IIT)]
on IK amido -- sopernooctsmarneicobalt UD,
OR tirammine cobalt (U) amd -syperooteatmmine cobal (I)
Fortis complexion, nagneie moment ei Oz ende
prod)
te ting dh teri (u ig Bars an il, be
ligands are named first. For example EN
co
Core <> Foo),
tii carbon bis (ricarbonylirofO)]
e. ti ue carbonyl nexacarbonylizon(0)
Ite bridging ligand bridges more than two metal centres, pre ele used o indicate the
number of metal centres bridged with a given ligand. For exaipe, in basic berytium eciat,
[Be10(CH:C00)1,0* ligand bridges four Be atoms. Therefor, he name ofthis compound is
4.010 hexa- -aceao tetrberfium (1)
‘The structure of basic heryium acetates shown in Figure 3.1
Hye
Rene 3 Lire ai oups OS
Same ote examples of ridged poynucear completes ar how below
o [HN sCo—NHs — CAN (OIC
Ramin cosa) > mido taria quo) chloride
Nt
@ A yay
KO
amido - ja nitro bisfteraammine cobalt]
OR amido - y-itro octemminediccbalQl)
OR tetraammine cobalt (11) --emido- proto termmine cobalt)
NE
AR
CONTI Cat cr
0
eamido- p=soperoxo bis [riamuninechoracaa!
NB
w ¡A Co LC 2G”
CE
ttammine cobalt amido - upon ianminsichloe col)
Note: A symmetrie bridged dinuclear complex, can be named by any three methods as shown
ess in examples (), (i) and (i) ut an unsymmer complex can be named by only one method as
given in example (iv)
a
0) [(SnCI3)2 RA) RSC) JA
Sa 5
ie u-chlorobisrichlorostanylhodan(t]
= = D as 3 PRESTO:
ow RUN TS cated, ON “Thus, oxidation state of Pin both the complex ions i +2 which is a stable oxidation state
No, 7
tr imido- 1 peroo rafale) cabal) nitrate
oH
(HN) Cr LOHR > CNHs)"
(ON), CH Ca
tri ne hydroxo bis{uiammine chromic)
o tei ydroxohexaammine dicobal (U)
Naming of Coordination Compounds having Cation and Anion both as Complex
fons
‘fan onie complex compound contin both the cation and anion as complex ions, he metal ction
in complex cation Pas its usual name but in complex aioe, the meal name ends in ate. Though, iis
fiel o calculate the oxidation states of two metals imo two complex ions yet, for caleulmion of
‘oxidation number of metals the hit and tial method is used. For his itis to be known the common
oxidation states ofthe two relevant metals.
The hit and trial method of calculation of oxidation states is illustrated by considering some
‘examples as given below
Example 1: (PrONHS )(PrCl4]
In complex of platinum, the common (or sable) oxidation sats are +2 and +4. Thus the positive
and negative charges on complex cation and complex anion should satisfy one ofthese two oxidation
ses or both,
“To decide whether Pin both the complexion has +2 or 4 or +2 in one complexion and +4 in the
‘other, we calculate he oxidation states of Pin bat complex ons by considering the following pins
(6) Ifwe consider-1 charge on anon, thea charge one cation will be +1. Thus, oxidation state of
tin complex cation ad complex anion can be calculated as
Complex cation, Complex anion
PINS Le par
240241 1
1
‘Thus, oxidation states of Pt are +1 and +3 which are not shown by platinum. Therefore, itis
wrong.
{Gi IF consider ~2ehogeon comple non, then charge on complex cation will be #2. Tus
‘oxidation states oF Pin he te oe an be aloud as
Complex cation
(PQs ro
540242
2
ñ Gi) HF we consíder-3 charge on ion, hen charge on complex cation will be +3.
Complex cation Complex anion
PR (Pcl
24028 sod
ve 1
‘Therefore, oxidation state of Ptare+1 and 3,
(Gv) Now in the last if we consider, 4 charge on complex anion, then charge on cation willbe +4.
‘Therefore oxidation states of Prin complex cation and complex anion will be +4 and 0
respectively
Complex cation Complex anion
IP Or
4 edad
“The oxidation states calculated in points number (1), (i) and (iv) are not the common oxidation
states of Pt. The oxidaion stat calculated in point number) is +2 in both the complex ions which sthe
‘one of the two common oxidation stes and it sts the charges on te complex cation and anin,
Therefore, the name ofthe compl is
tetraammineplatinundl}) etracloroplatinate(1)
Example 2: [PEN [PICL]
Oxidation stats of Pin both he complexions canbe called as discussed eater
‘Complex cation ‘Complex anion
o CNRS pay eo prie
40-2241 rs
28 ea
@ [LO gla (pci
40-2242 34
4 12
i PENH) CH] ra
140-2233 140-3
5 Port
ow RUN TS cated, ON “Thus, oxidation state of Pin both the complex ions i +2 which is a stable oxidation state
No, 7
tr imido- 1 peroo rafale) cabal) nitrate
oH
(HN) Cr LOHR > CNHs)"
(ON), CH Ca
tri ne hydroxo bis{uiammine chromic)
o tei ydroxohexaammine dicobal (U)
Naming of Coordination Compounds having Cation and Anion both as Complex
fons
‘fan onie complex compound contin both the cation and anion as complex ions, he metal ction
in complex cation Pas its usual name but in complex aioe, the meal name ends in ate. Though, iis
fiel o calculate the oxidation states of two metals imo two complex ions yet, for caleulmion of
‘oxidation number of metals the hit and tial method is used. For his itis to be known the common
oxidation states ofthe two relevant metals.
The hit and trial method of calculation of oxidation states is illustrated by considering some
‘examples as given below
Example 1: (PrONHS )(PrCl4]
In complex of platinum, the common (or sable) oxidation sats are +2 and +4. Thus the positive
and negative charges on complex cation and complex anion should satisfy one ofthese two oxidation
ses or both,
“To decide whether Pin both the complexion has +2 or 4 or +2 in one complexion and +4 in the
‘other, we calculate he oxidation states of Pin bat complex ons by considering the following pins
(6) Ifwe consider-1 charge on anon, thea charge one cation will be +1. Thus, oxidation state of
tin complex cation ad complex anion can be calculated as
Complex cation, Complex anion
PINS Le par
240241 1
1
‘Thus, oxidation states of Pt are +1 and +3 which are not shown by platinum. Therefore, itis
wrong.
{Gi IF consider ~2ehogeon comple non, then charge on complex cation will be #2. Tus
‘oxidation states oF Pin he te oe an be aloud as
Complex cation
(PQs ro
540242
2
ñ Gi) HF we consíder-3 charge on ion, hen charge on complex cation will be +3.
Complex cation Complex anion
PR (Pcl
24028 sod
ve 1
‘Therefore, oxidation state of Ptare+1 and 3,
(Gv) Now in the last if we consider, 4 charge on complex anion, then charge on cation willbe +4.
‘Therefore oxidation states of Prin complex cation and complex anion will be +4 and 0
respectively
Complex cation Complex anion
IP Or
4 edad
“The oxidation states calculated in points number (1), (i) and (iv) are not the common oxidation
states of Pt. The oxidaion stat calculated in point number) is +2 in both the complex ions which sthe
‘one of the two common oxidation stes and it sts the charges on te complex cation and anin,
Therefore, the name ofthe compl is
tetraammineplatinundl}) etracloroplatinate(1)
Example 2: [PEN [PICL]
Oxidation stats of Pin both he complexions canbe called as discussed eater
‘Complex cation ‘Complex anion
o CNRS pay eo prie
40-2241 rs
28 ea
@ [LO gla (pci
40-2242 34
4 12
i PENH) CH] ra
140-2233 140-3
5 Port
Ly
PRES
REST ind a
(0) Pa
190-244
1216
‘The oxidation states calculated ia point number (), (i) and (iv) ae notthe common oxidation states
of Pt
‘The oxidation stats of Pt calculated in point marie (ji) are 44 and 42 in comple cation and anion
respectively which are the common oxidation states of P. Therefore the name ofthe complex
‘eraamminedicocoplatinum(TV) tetrachloroplatnate(t)
‘An anther method to decide the oxidation states of Pt in complex ons:
Prin oxidation sae of +2 always frm complexes or complexions of coordination number dand Pe
in oxidation state of +4 alway fonas complexes of coordination number a. For example :
CPO}, ROA]
In this complex compound, coordination number of Pt in both the complex cation and complex
anions 4. Therefore oxidation state of Pin both the complex ions is #2. Thus name ofthe complex is.
‘eearaninepltiound{) tetrachioroplatinateS)
(i) (PE Cig Ch)
In this complex, coordination mumber of Pt in complex cation is 6 and in complex anion is 4.
Therefore the oxidation states of Prin complex cation and complex anion are +4 and 42 respectively
‘Therefore the name ofthe comple is
‘etranmninedichlropltinum(LV) terachlorpatinate1)
Example 3 : {CH(NH3)g] {CaF}
In such type of complexes the common oxidation states of both Cr and Co are +2 and +3
respectively. Thus either ofthese oxidation states ofboth would satis the charges on complex cation
and complex anion, Oxidation sates of Cand Co can be calculated ss
Complex etion ‘Complex anion
@ [CANIS [Coro
Bryan
sen
Natshow by Cr Nor shown by Co
(trcomee)
| @ LUN
240212
12
Showmby Cr Notshawnby Co
incorrect)
0) IC) [cof
63
128 18
Shown by Cr Showabyco
(Carex)
ww (CL Lore“
2624
144 raid
Nerstown by Cr Shown ly Co
(rear)
Q] CNT
1. 2.
Not shown by Cr Not stow by Co
(incorrect),
0) UA (cof
3246
otstownby Cr Not shown by Co
(comet)
“The cautions given above for oxidation states of Cr and Co show hat oxidation states of Cr and
Co in compix cation and complex anion is +3 which satisfies the charges où complex cation and
Complex anion ard is the common oxidation state for both. Therefore, the name of the complex
compounds is ee
herasmmine chrome) hexailuorocobatat(tt)
Some Examples of Such Type of Complexes are Given Below
6) [Coten)a] [CREM ct tri(ethylenediamine)oobet(U besacyanoctromate 11)
OPIO tetrapyridinepatinun(Q)tetachorpltnae)
PRES
REST ind a
(0) Pa
190-244
1216
‘The oxidation states calculated ia point number (), (i) and (iv) ae notthe common oxidation states
of Pt
‘The oxidation stats of Pt calculated in point marie (ji) are 44 and 42 in comple cation and anion
respectively which are the common oxidation states of P. Therefore the name ofthe complex
‘eraamminedicocoplatinum(TV) tetrachloroplatnate(t)
‘An anther method to decide the oxidation states of Pt in complex ons:
Prin oxidation sae of +2 always frm complexes or complexions of coordination number dand Pe
in oxidation state of +4 alway fonas complexes of coordination number a. For example :
CPO}, ROA]
In this complex compound, coordination number of Pt in both the complex cation and complex
anions 4. Therefore oxidation state of Pin both the complex ions is #2. Thus name ofthe complex is.
‘eearaninepltiound{) tetrachioroplatinateS)
(i) (PE Cig Ch)
In this complex, coordination mumber of Pt in complex cation is 6 and in complex anion is 4.
Therefore the oxidation states of Prin complex cation and complex anion are +4 and 42 respectively
‘Therefore the name ofthe comple is
‘etranmninedichlropltinum(LV) terachlorpatinate1)
Example 3 : {CH(NH3)g] {CaF}
In such type of complexes the common oxidation states of both Cr and Co are +2 and +3
respectively. Thus either ofthese oxidation states ofboth would satis the charges on complex cation
and complex anion, Oxidation sates of Cand Co can be calculated ss
Complex etion ‘Complex anion
@ [CANIS [Coro
Bryan
sen
Natshow by Cr Nor shown by Co
(trcomee)
| @ LUN
240212
12
Showmby Cr Notshawnby Co
incorrect)
0) IC) [cof
63
128 18
Shown by Cr Showabyco
(Carex)
ww (CL Lore“
2624
144 raid
Nerstown by Cr Shown ly Co
(rear)
Q] CNT
1. 2.
Not shown by Cr Not stow by Co
(incorrect),
0) UA (cof
3246
otstownby Cr Not shown by Co
(comet)
“The cautions given above for oxidation states of Cr and Co show hat oxidation states of Cr and
Co in compix cation and complex anion is +3 which satisfies the charges où complex cation and
Complex anion ard is the common oxidation state for both. Therefore, the name of the complex
compounds is ee
herasmmine chrome) hexailuorocobatat(tt)
Some Examples of Such Type of Complexes are Given Below
6) [Coten)a] [CREM ct tri(ethylenediamine)oobet(U besacyanoctromate 11)
OPIO tetrapyridinepatinun(Q)tetachorpltnae)
‘TUPAC NE Cordial Compounds
Gi (COQ) CHE) Cas
In his complex, it is seen clearly thatthe charge on complex cation and complex anion will be 43
and 1 respectively, Therefore, oxidation states of Co and Crean becaleulaedas +
Complex e Complex anion
ICON)" {CAN ¿QT?
140243 240-6221
3 3
“The oxidation sates of both Co and Cris +3. Therefore, name ofthe complex is:
hhexaamsnine cobalt!) teraarninedichiorockromate( ii)
GC) (CSN ZAC |
In complexes Zn shows only +2 oxidaion stat, therefore, charge on complex anion is -2 and,
‘therefore, te cage on complex ation wal be 42.
Complex ation Complex anion
ICE) (NC (cle
240-128
3
Oxidation sates of Cr = 43
‘Ths, the name ofthe comple is:
pentaansninetiocyanato-N chromisenll) tetrachlerozineteI)
(IEA FeCl
Inthis comple, ts seen hat he chärge on complex cations +3 and ebsgeon complex anion is-1
Therefore, oxidation state of Fe in complex cation and complex anion can be celeulated as:
Complex cation ‘Complex anion
[Feen]
240043
3 Pr
The oxidation state of Fe in both the complex ions is +3, Therefore, the name of the complex
compound is
‘rs(thylenediamine)iron(I}) tetrachoroferatett)
CORE) Br )IafZaCL4]
In this complex, charges on complex cation and complex anion are +1 and -2 respectively
‘Therefore, the oxidation states of cobalt and zinc can be calculated a
Complex cation Complex aston
(CoN) Br? mayo
240-2241
PE
‘Therefore, oxdiation states of cobalt and zinc are +3 and +2 respectively.
‘Therefore, the name of he complex is
tetraamuminedibromocobal(itl) tetrachlorozincatect)
TN
{thasbeen observed experimental aro elements of group IL, Ca, Ag, Ati oxidation
stat and Hg in +2 oxidation state form complexes ofcoardination number. Therefore in his complex
oxidation tate of Agis + in both the complexions. Therefore, he name ofthe complex compound is
iammine silver) dicyanoargentate()
(ii) (Ral SN) [PHC
Int complex, coordination number of Pts 4, therefore, oxidation state of Pris +2. This indicates,
that charge on complex anion is -2 and onthe complex cation is +2.
Complex cation
ON
4040-42
22
The oxidation numer calculations show that the oxidation sat of both Ruand Pris42. Therefore,
the name of he complex compound is
Pentuammminginitrogenruhendumfl) tetrachloropatintel)
Gi (COQ) CHE) Cas
In his complex, it is seen clearly thatthe charge on complex cation and complex anion will be 43
and 1 respectively, Therefore, oxidation states of Co and Crean becaleulaedas +
Complex e Complex anion
ICON)" {CAN ¿QT?
140243 240-6221
3 3
“The oxidation sates of both Co and Cris +3. Therefore, name ofthe complex is:
hhexaamsnine cobalt!) teraarninedichiorockromate( ii)
GC) (CSN ZAC |
In complexes Zn shows only +2 oxidaion stat, therefore, charge on complex anion is -2 and,
‘therefore, te cage on complex ation wal be 42.
Complex ation Complex anion
ICE) (NC (cle
240-128
3
Oxidation sates of Cr = 43
‘Ths, the name ofthe comple is:
pentaansninetiocyanato-N chromisenll) tetrachlerozineteI)
(IEA FeCl
Inthis comple, ts seen hat he chärge on complex cations +3 and ebsgeon complex anion is-1
Therefore, oxidation state of Fe in complex cation and complex anion can be celeulated as:
Complex cation ‘Complex anion
[Feen]
240043
3 Pr
The oxidation state of Fe in both the complex ions is +3, Therefore, the name of the complex
compound is
‘rs(thylenediamine)iron(I}) tetrachoroferatett)
CORE) Br )IafZaCL4]
In this complex, charges on complex cation and complex anion are +1 and -2 respectively
‘Therefore, the oxidation states of cobalt and zinc can be calculated a
Complex cation Complex aston
(CoN) Br? mayo
240-2241
PE
‘Therefore, oxdiation states of cobalt and zinc are +3 and +2 respectively.
‘Therefore, the name of he complex is
tetraamuminedibromocobal(itl) tetrachlorozincatect)
TN
{thasbeen observed experimental aro elements of group IL, Ca, Ag, Ati oxidation
stat and Hg in +2 oxidation state form complexes ofcoardination number. Therefore in his complex
oxidation tate of Agis + in both the complexions. Therefore, he name ofthe complex compound is
iammine silver) dicyanoargentate()
(ii) (Ral SN) [PHC
Int complex, coordination number of Pts 4, therefore, oxidation state of Pris +2. This indicates,
that charge on complex anion is -2 and onthe complex cation is +2.
Complex cation
ON
4040-42
22
The oxidation numer calculations show that the oxidation sat of both Ruand Pris42. Therefore,
the name of he complex compound is
Pentuammminginitrogenruhendumfl) tetrachloropatintel)
laming of Complexes Containing Hydrated Water Molecules
In the coordination compounds which have hydrated water molecules, the number of water
ecules are designated inthe last ofthe name ofa complex compound separated by a space as shown
How
m0 monohydrate
umo sesquihydrate
2,0 dihydrate
30 teiydrate and so fh
‘An important example is given below
Kz [Fe(CN)s(NO}}-2H20
potassium pentacyanontrosyiferat() dihydrate
Jaming of Geometrical Isomers
Geometrical isomers are named either by using the prefixes ci and trans-ot fac (Le, facial) and
er. (a, meridional) o by numbering system. Ifa complex shows only two geometrical isomers, the
fixes is os ans and fac- or mer-ate used before the name of the compound separating by hyphen.
more than two gsometrial isomers are possible fo a complex, then oly numbering system can be
bd, Fr example
cs tetramamindichlorocobslt(I})
‘rans tetreamminedichlorocobal(U)
ecctisqutrichlorocheomviue(UD)
-mer-tiaquatichlorochromium(l)
(E Bein)
h
“JE sigan
A
Lye
Naming of Optical Isomers
Optical isomers are designated either by dor +) or (or) where de and are standing for
destrrotaary ad levorotatory respectively For example
arifetylenediamine)cabal(t)
NT
on
2.
a
drisfeihylenediamine)eobait)
In the coordination compounds which have hydrated water molecules, the number of water
ecules are designated inthe last ofthe name ofa complex compound separated by a space as shown
How
m0 monohydrate
umo sesquihydrate
2,0 dihydrate
30 teiydrate and so fh
‘An important example is given below
Kz [Fe(CN)s(NO}}-2H20
potassium pentacyanontrosyiferat() dihydrate
Jaming of Geometrical Isomers
Geometrical isomers are named either by using the prefixes ci and trans-ot fac (Le, facial) and
er. (a, meridional) o by numbering system. Ifa complex shows only two geometrical isomers, the
fixes is os ans and fac- or mer-ate used before the name of the compound separating by hyphen.
more than two gsometrial isomers are possible fo a complex, then oly numbering system can be
bd, Fr example
cs tetramamindichlorocobslt(I})
‘rans tetreamminedichlorocobal(U)
ecctisqutrichlorocheomviue(UD)
-mer-tiaquatichlorochromium(l)
(E Bein)
h
“JE sigan
A
Lye
Naming of Optical Isomers
Optical isomers are designated either by dor +) or (or) where de and are standing for
destrrotaary ad levorotatory respectively For example
arifetylenediamine)cabal(t)
NT
on
2.
a
drisfeihylenediamine)eobait)
ESO
Af a complex has optically active moecles, Te configuration of the whole molecule or ion is
represa by do end tha ofthe gend moles by D- or L-
For example
‘eis d4Co(en) (D-Pr)NO2)2]* and eis-H[Cofen) (L-po)(NO2)21*
IUPAC Nomenclature on the Basis of Charge Number
net charge onthe complex io is call tb charge number A charge number cun be used as
eo On mie Te cs nd mp ently a eran
‘The number along With te sign ofthe charge is oclosed in paretheses. No space i ef between the
number and the rest ofthe name.
For example
ICONE) hexzammincoobal(3+)
[FEN Y" hexscyanoferate (3-) or hekagyanidoferrate(3-)
[Co(NH3)3(NO2)3) ‘triamminetrinitrito-N-cobalt(0)
1CANO2)6 1" hhexanitito-N-cobaltate (3-)
1. Oxidation state of Ptin complex cation and complex anion in[PHONE Cha JEPICH J
and apie E
Es jé
2. Oxidation state of cobalt in | (H3N)4( Co(NHy), de ns and Ht is a
OS
„complex
3 (CG) (NUS O]. rade god an y share for.
Ni W
Inthe complex [Hs MI¿COG( COD | he prefix eis used forte igs ae
%
„and.
“The IUPAC name ofthe complex fac {CO(CHs NH )sCI5 …
‘The IUPAC name ofthe complex (Be 40{CH3000) is
Ni? (ag) reacts with alcoolic solution ofdimethylglyoxime in alkaline medium, a red colour
complex is formed. The TUPAC name ofthis products un
‘The complex (CO(NHs)3(NO3}s] show two geometrical isomers namely ..
pan
… ad
fans. L 4,82 2. 43, bridged
3. als, eycinato 4 NH5,03
5. factichiorocs(metbylaning}cob ati)
6. wa-oxohexaqeaoetttetraberyium
7. bis(dimetiyllyoxinatonickel{l) 8. facial, meridional}
tive Que:
1. The IUPAC name ofeisfCnfen),Ch]" is
4G) biseihylenediaminedihleobagm BL, 7
eee A
(de deis 1 2-6
4d) ais dichlorodi(ethylenediamine)cobalt(Ln) uo. es
2. The IUPAC came: of trans {Can «(NH Ja” is: w
(6) rans-diaminetetraioihicycanatochromte(t) Y X
(©) trans daraineteristhiocyanstocbromateT)
(0) tans teteisoticeyanatodiamnieshromiom(U],
(4) trans-diamminetetaisotbioeyanatochromiuanI)
Af a complex has optically active moecles, Te configuration of the whole molecule or ion is
represa by do end tha ofthe gend moles by D- or L-
For example
‘eis d4Co(en) (D-Pr)NO2)2]* and eis-H[Cofen) (L-po)(NO2)21*
IUPAC Nomenclature on the Basis of Charge Number
net charge onthe complex io is call tb charge number A charge number cun be used as
eo On mie Te cs nd mp ently a eran
‘The number along With te sign ofthe charge is oclosed in paretheses. No space i ef between the
number and the rest ofthe name.
For example
ICONE) hexzammincoobal(3+)
[FEN Y" hexscyanoferate (3-) or hekagyanidoferrate(3-)
[Co(NH3)3(NO2)3) ‘triamminetrinitrito-N-cobalt(0)
1CANO2)6 1" hhexanitito-N-cobaltate (3-)
1. Oxidation state of Ptin complex cation and complex anion in[PHONE Cha JEPICH J
and apie E
Es jé
2. Oxidation state of cobalt in | (H3N)4( Co(NHy), de ns and Ht is a
OS
„complex
3 (CG) (NUS O]. rade god an y share for.
Ni W
Inthe complex [Hs MI¿COG( COD | he prefix eis used forte igs ae
%
„and.
“The IUPAC name ofthe complex fac {CO(CHs NH )sCI5 …
‘The IUPAC name ofthe complex (Be 40{CH3000) is
Ni? (ag) reacts with alcoolic solution ofdimethylglyoxime in alkaline medium, a red colour
complex is formed. The TUPAC name ofthis products un
‘The complex (CO(NHs)3(NO3}s] show two geometrical isomers namely ..
pan
… ad
fans. L 4,82 2. 43, bridged
3. als, eycinato 4 NH5,03
5. factichiorocs(metbylaning}cob ati)
6. wa-oxohexaqeaoetttetraberyium
7. bis(dimetiyllyoxinatonickel{l) 8. facial, meridional}
tive Que:
1. The IUPAC name ofeisfCnfen),Ch]" is
4G) biseihylenediaminedihleobagm BL, 7
eee A
(de deis 1 2-6
4d) ais dichlorodi(ethylenediamine)cobalt(Ln) uo. es
2. The IUPAC came: of trans {Can «(NH Ja” is: w
(6) rans-diaminetetraioihicycanatochromte(t) Y X
(©) trans daraineteristhiocyanstocbromateT)
(0) tans teteisoticeyanatodiamnieshromiom(U],
(4) trans-diamminetetaisotbioeyanatochromiuanI)
E TIR PIO Mein
3. offdation number of Os in [NOXP Pb Ils (NE is: we Rat
(a) #2 © A HT e
(0) +5 as 7 A
4, The IUPAC name ofmer{C00NO) ins AU
(9 meretsleneianinetinitocobal(t)
(©) mer dityleiaramisetrinivocobal UI)
(© merdiyercsiamicetinisocoali)
mertiirodietylencisminecobalt 1D
TUPAC name Na FC) NOJis
(6) sodium penaasonitesyt ron)
(9) sodium pentacyanonirosonum mac)
(© sodium sinesoatumpentaeyano fete)
sodium itcosypentacyano fea)
Wich one fe ling ia conet representation of eri nel enr
un?
GINO) FCN) or
ONF (Ot a
The TUPAC nomenclature of Na[PC is ajos
(6) sativa heachorophashine(V) (sodium hexachlorophaspate(V) 7
(©) secu heachlorophesphine (sodium hesachlorophosphite(Y)
> ARSIDERS
LO 20 20 40 FM 6@ 7
a
1. Weite he IUPAC name ofthe following complexes +
OLE TRICK] (0) (CANE) {COR}
OC) ]INKCN)} (6) (Co(NH3)5ONO]
4 Aca CO INiQNH3)2(H0)(NO»)}Br
2. Write the formula of following complexes:
À (often ein coseno) dite
(©) Diamine ding iano cabal) chloride
(© Pentamine isotioeyanst um tecachiorozincate()
(@ Sodium citioniphstosrgentey
(€) Tetcammine catonstocobalfil chloride
(9 Poussin eraftoroargetate
ada
Theories for Meta
‘There sete boris expan he au of bong in sion mel lee
(0) Valence Bond Theos (VBT) =
@) Crystal Fiel Theory CET) — aut!
(©) Ligand Field Theory (LFT or Molecular Orbital Theory (MOT) or Adjusted Crystal Field
‘Theory (ACHT) a
(1) Valence Bond Theory
Tris theory developed ely by Pauling This theory is based on te fllowing assumptions
(D Fiesta cn cto a as moy be) es ables nbs ft
oxbitls on he Ligands.
(2) Since te maxinum angola overlap of to orbial forms the strongest bond, therefore, these
vacant atomic obials of metal are hybridized to forma now set of equivalent boing orbital,
called bid orbitals. These orbitals have same geometry and arme energy. These orbitals also
have deficit directional properties Le, these orbitals point in the icon of ligands. The
gebmetry and hybridization ae related 10 one another. Once you know the geometry of a
complex compound, you automatically keow which orale afte metal cation o atom uses
Thereatoeshipbetwoen the geometry ofthe complex aná hybridizaontsgivenió Table 4.1.
(3) The bonding in metal complexes arises when a filled ligand orbital containing alone pair of
electrons overlaps a vacant hybrid orbital on e metal cation or atom to fora s coordinate
covalent bond (Figue 4.1).
ou) G@>1o —ondDio
Vocsreme = Ugandoril Coote cat
Hd contanng pair ond
“ct
Figure
(4 The magnetic moment (ie, he number of unpaicd cletrons) and te cortinain numberof
the meta cto or so decido the hybridization and geomenyof te comple Three,
magnetic moment, coordination number, hybridization and geomesy ae rested to one
3. offdation number of Os in [NOXP Pb Ils (NE is: we Rat
(a) #2 © A HT e
(0) +5 as 7 A
4, The IUPAC name ofmer{C00NO) ins AU
(9 meretsleneianinetinitocobal(t)
(©) mer dityleiaramisetrinivocobal UI)
(© merdiyercsiamicetinisocoali)
mertiirodietylencisminecobalt 1D
TUPAC name Na FC) NOJis
(6) sodium penaasonitesyt ron)
(9) sodium pentacyanonirosonum mac)
(© sodium sinesoatumpentaeyano fete)
sodium itcosypentacyano fea)
Wich one fe ling ia conet representation of eri nel enr
un?
GINO) FCN) or
ONF (Ot a
The TUPAC nomenclature of Na[PC is ajos
(6) sativa heachorophashine(V) (sodium hexachlorophaspate(V) 7
(©) secu heachlorophesphine (sodium hesachlorophosphite(Y)
> ARSIDERS
LO 20 20 40 FM 6@ 7
a
1. Weite he IUPAC name ofthe following complexes +
OLE TRICK] (0) (CANE) {COR}
OC) ]INKCN)} (6) (Co(NH3)5ONO]
4 Aca CO INiQNH3)2(H0)(NO»)}Br
2. Write the formula of following complexes:
À (often ein coseno) dite
(©) Diamine ding iano cabal) chloride
(© Pentamine isotioeyanst um tecachiorozincate()
(@ Sodium citioniphstosrgentey
(€) Tetcammine catonstocobalfil chloride
(9 Poussin eraftoroargetate
ada
Theories for Meta
‘There sete boris expan he au of bong in sion mel lee
(0) Valence Bond Theos (VBT) =
@) Crystal Fiel Theory CET) — aut!
(©) Ligand Field Theory (LFT or Molecular Orbital Theory (MOT) or Adjusted Crystal Field
‘Theory (ACHT) a
(1) Valence Bond Theory
Tris theory developed ely by Pauling This theory is based on te fllowing assumptions
(D Fiesta cn cto a as moy be) es ables nbs ft
oxbitls on he Ligands.
(2) Since te maxinum angola overlap of to orbial forms the strongest bond, therefore, these
vacant atomic obials of metal are hybridized to forma now set of equivalent boing orbital,
called bid orbitals. These orbitals have same geometry and arme energy. These orbitals also
have deficit directional properties Le, these orbitals point in the icon of ligands. The
gebmetry and hybridization ae related 10 one another. Once you know the geometry of a
complex compound, you automatically keow which orale afte metal cation o atom uses
Thereatoeshipbetwoen the geometry ofthe complex aná hybridizaontsgivenió Table 4.1.
(3) The bonding in metal complexes arises when a filled ligand orbital containing alone pair of
electrons overlaps a vacant hybrid orbital on e metal cation or atom to fora s coordinate
covalent bond (Figue 4.1).
ou) G@>1o —ondDio
Vocsreme = Ugandoril Coote cat
Hd contanng pair ond
“ct
Figure
(4 The magnetic moment (ie, he number of unpaicd cletrons) and te cortinain numberof
the meta cto or so decido the hybridization and geomenyof te comple Three,
magnetic moment, coordination number, hybridization and geomesy ae rested to one
3 3 Cain Cents
another, The knowledge of magnetic moment canbe of reat help in ascetining he nature of
Sigand and type of complex.
(6) Each ligand ts atleast one octal containing a one pi of elecrns. Pauling classified the
liga ito two categories: () strong clecton doratng ligands or simply strong ligands like
CO etc. (i) weak ligands or highly eletoneguive liginds, like F",CI", oxygen
containing igands ec. a
(9 Strong ligands have the tendency o air up the d-clectrons of mets cation or atom to provide
‘th necessary orbitals for hybridization Bul he pirng of electrons does ot ioat the land's
‘ule of maximum muliplity. On the other hand, weak ligands donothave the tendency to pair
bed elecrons ce, in presence of weak ligands electronic configuration ofthe electrons
is same ein fee metal ction or atom.
D The bond fomed between metal ard song ligand such as CN”, CO is considered ta be
Feat On the eter had, the bord formed beeen ml and weak or highly
decronegative grd like F is not covalent but itis ion
(& The bond formed between metal and strong ligand like CN”, CO ex. is considered to be
orales. Tis woud requir in many cases the pang of delecuon to provide the necessary
tial for hybridization,
(0) Inoctabodral complexes, the central metal cation i eter dsp orsp a ybeiize, The
<r involved in dsp? bybriiztion belong to the ine tll {13 -obials and
these complex are called as inner orbital complexe. In ete of sp? hybridization, the de
orbitals belong o outer most sell, n - orbitals and the complexes ar called outer orbital
Complexes. The othedral complexe involving d?sp-Aybization are more stable than
tose ofp’. Tie. oral involved in bia in xa compos à
anda.
In tada) complexes, the metal cation or atom is either sp? or si?-bybrdized. The
débits involved in sd -hybridiation ate dy, dye and,
In square planar complexes, the metal cation is dip? tybridized. The p- and d- orbitals
‘involved in diz? Aybriizao ae pr, pyand da leaving pa ad oral projecting
>. above si bel te plane ofthe complex,
Go) cai of second a il series arson mel cole, ie eras ievlvd in
ization are faner orbitals Le. (a ~ 1) de orbital, because the outer d- oils Le, ad
‘orbitals became too diffuse to bond well
(11) The complexes having 00e or more unpaired electrons are paremagnei and the complexes.
having only paired electrons are diamsgneic Be
Hybrid Ocbitals for Common Coordination Geometries
@ ¿Orbis arabes [Bond Angle ()| Geametey sample
2 Io sand py | 180% | Linea [Agi]
ale 5 Pad py [ur [eur ey
para
=
Péri Banding i Complex * 3
4 lo 5 Po By and py | 109 Tantedat |(Cocu,
Nu
a le Sedge dyn dag | 109 Terahatad 103,007
cor
rs
5 Ps Py 0 Square planar psico]
se ae)
“18 2
Pda a | 90° Square planar (CNE )4
pa sr, - je)
ee a? |90%,520% | Trigonad Fe{CO)s
5 jae $ De Py Pa leon
5 à $ Par Pao Pr and | 90°,90° Square Ns"
Ed aa pyramidal
a? dp. py, Ape, 99° | toner oil PE
Bday and ida rail | et
6 |g ET Outer oral (CA OL,
y '
DRE E pre
‘Now lets discuss the valence bond theory for octahedra, trhedrat and square planar complexes
taking some examples
Octahedral Complexes
(A) Inner Orbital Complexes: Let us discuss imer orbital complexing aking some examples
1.(CHCNJel"" ion: Inthis complex. oxidation state of cobalt is +3. Th valence shell electronic
configuraonofCa**is34%, Magaetic measurements indicate that{Co(CN)¢]* isdiamsgneti. AU six
1 -lectronsare therefore, paired and occupy Ihre ofthe five 34-etbial. The CN” ligands are strong
anderer, case pring of 34 electrons. The vacant two 3-abitals combine withthe vacant 4 und
portal to form six dsp? bi orbital. These six hybrid orbital vertap with six filled orbitals of
gad, onen ech ofthe ian nd ts six connate covalent Bonds a formed
En E
eS man
om = o na]
(coe m STE
promet
Asien Salon
¿atan
octet
another, The knowledge of magnetic moment canbe of reat help in ascetining he nature of
Sigand and type of complex.
(6) Each ligand ts atleast one octal containing a one pi of elecrns. Pauling classified the
liga ito two categories: () strong clecton doratng ligands or simply strong ligands like
CO etc. (i) weak ligands or highly eletoneguive liginds, like F",CI", oxygen
containing igands ec. a
(9 Strong ligands have the tendency o air up the d-clectrons of mets cation or atom to provide
‘th necessary orbitals for hybridization Bul he pirng of electrons does ot ioat the land's
‘ule of maximum muliplity. On the other hand, weak ligands donothave the tendency to pair
bed elecrons ce, in presence of weak ligands electronic configuration ofthe electrons
is same ein fee metal ction or atom.
D The bond fomed between metal ard song ligand such as CN”, CO is considered ta be
Feat On the eter had, the bord formed beeen ml and weak or highly
decronegative grd like F is not covalent but itis ion
(& The bond formed between metal and strong ligand like CN”, CO ex. is considered to be
orales. Tis woud requir in many cases the pang of delecuon to provide the necessary
tial for hybridization,
(0) Inoctabodral complexes, the central metal cation i eter dsp orsp a ybeiize, The
<r involved in dsp? bybriiztion belong to the ine tll {13 -obials and
these complex are called as inner orbital complexe. In ete of sp? hybridization, the de
orbitals belong o outer most sell, n - orbitals and the complexes ar called outer orbital
Complexes. The othedral complexe involving d?sp-Aybization are more stable than
tose ofp’. Tie. oral involved in bia in xa compos à
anda.
In tada) complexes, the metal cation or atom is either sp? or si?-bybrdized. The
débits involved in sd -hybridiation ate dy, dye and,
In square planar complexes, the metal cation is dip? tybridized. The p- and d- orbitals
‘involved in diz? Aybriizao ae pr, pyand da leaving pa ad oral projecting
>. above si bel te plane ofthe complex,
Go) cai of second a il series arson mel cole, ie eras ievlvd in
ization are faner orbitals Le. (a ~ 1) de orbital, because the outer d- oils Le, ad
‘orbitals became too diffuse to bond well
(11) The complexes having 00e or more unpaired electrons are paremagnei and the complexes.
having only paired electrons are diamsgneic Be
Hybrid Ocbitals for Common Coordination Geometries
@ ¿Orbis arabes [Bond Angle ()| Geametey sample
2 Io sand py | 180% | Linea [Agi]
ale 5 Pad py [ur [eur ey
para
=
Péri Banding i Complex * 3
4 lo 5 Po By and py | 109 Tantedat |(Cocu,
Nu
a le Sedge dyn dag | 109 Terahatad 103,007
cor
rs
5 Ps Py 0 Square planar psico]
se ae)
“18 2
Pda a | 90° Square planar (CNE )4
pa sr, - je)
ee a? |90%,520% | Trigonad Fe{CO)s
5 jae $ De Py Pa leon
5 à $ Par Pao Pr and | 90°,90° Square Ns"
Ed aa pyramidal
a? dp. py, Ape, 99° | toner oil PE
Bday and ida rail | et
6 |g ET Outer oral (CA OL,
y '
DRE E pre
‘Now lets discuss the valence bond theory for octahedra, trhedrat and square planar complexes
taking some examples
Octahedral Complexes
(A) Inner Orbital Complexes: Let us discuss imer orbital complexing aking some examples
1.(CHCNJel"" ion: Inthis complex. oxidation state of cobalt is +3. Th valence shell electronic
configuraonofCa**is34%, Magaetic measurements indicate that{Co(CN)¢]* isdiamsgneti. AU six
1 -lectronsare therefore, paired and occupy Ihre ofthe five 34-etbial. The CN” ligands are strong
anderer, case pring of 34 electrons. The vacant two 3-abitals combine withthe vacant 4 und
portal to form six dsp? bi orbital. These six hybrid orbital vertap with six filled orbitals of
gad, onen ech ofthe ian nd ts six connate covalent Bonds a formed
En E
eS man
om = o na]
(coe m STE
promet
Asien Salon
¿atan
octet
Res
2. {Co (NO>)e1* ton: In his complex ion, oxidation stat of cobalt is + 2 and its valence shel
electronic configuration is 34. Magnetic moment measurements indicate that this complexion is
paramagnetic corresponding to presence of one unpsiredelecton. The NOF ligands are strong, they,
therefore, cause pring of metal 34 electors, Paling suggested that two vacant 3d orbitals are made
avale by promotion of an unpaired elton from a habil to Ssorbital so that Co? jon pots
À parie.
‘The presence of an unpiced électron in Soil supported by he fat that, s- orbital bas very
igh energy and the electron present in its sel bond and can he removed easly Experimental à
ds also observed that [Co(NO2)6 1°" is oxidized by ai or HO) easily to give [Co(NO7)g]”. This
indicates that the complex [Co(NO2 Js" is unstable in air. Ths, this complex should be prepared in
ines atmosphere.
Mt
Coam
bos
ES MENO
e EDAD O
(cunt in EEN (1 vase
Aprilia
gi
3.1Mn (CN) ion : In this complex ion, oxidation states of Ma is + 3 and ts valence shell
tectonic configuration is 34. Magnetic mess »ments show that his complex ion is paramagnetic
ning to two unpaired electrons. AI i o. electron occupy just thee ofthe five 3d orbitals
esving two 34: orbitals vacant, These two vacant 32- obits combine with he vaca 4 and dp-
bas give six dsp? «hybrid orbitals. These hybrid orbitals form bonds with igands by accepting
x pair of electrons, one pair ftom each of the six ligands, Since CN” isa strong ligand and has a
dency lo par up the d- electrons on metal but it causes pairing of two eleetons only leving two.
eons as unpaired, Lai the electrons become paired, hen wil volte the Hand's rule of maximum
ipl.
Maton
Bea
Mal ion
MEN) ion bgp hyhidization
«en ny
Soe, eme
in ide
4-ICE(CMGF om la this complex ion, oxidation ste of Ces + 3 and is valence shell
"tonic configuration is 34°. Magnetic measurement show tht this complex ion is
men is complex ion is paramagnetic
responding (the presence of three unpuiced electrons, AI the thee 3d ~ electrons occupy just hree
‘of te five 3d - orbitals Leaving two 3d obitals a vacant. These two vacant orbitals combine withthe
vacant 4s and 4p-ocitels to give six d?sp*-tybeid orbitals, These ix hybrid orbitals form bonds with
ligands by accepting six lone pair flgands, oe pi fiom each ofthe six ligands. The thre orbital of
the metal cation have thee unpaired electrons and are degenerate Thus, even inthe presence of strong
ligands pairing of electrons will not occu If paiingof electrons ocur, then it will violate Hund’ sale of
maximum multiplicity
o PR
en Too
Pon GERTDOCID
LCI ion
Ferien Faller
¿o ition
cata
‘SIV (NIls)¢]°* fom: In thiscoplex in, xico sico vanadium is + 3 nd is valence sell
cri coligustion is 142. Magnetic measurements indicat tht this complex ion i pramagnetic
coreponting o two unpaired econ, A he to 3d leas occupy just tuo of tke five 34 =
cab leaving the 34 orbital vacant wo of which combine wi vacat ds and ép orbitals o give
sx «hybrid obits. The dsp? hd ofits far bond wih he igands accepting sx pis
ofelectons, one pi rom each ofthe six ligan. Ou of three 34 uaybrdized orbitals, two oras
tae two unpaired electrons one unaired electron in each and one orbital remains vacant, These three
hybrid 34 - obials are degencae. Ths, evn inthe presence of tong ligands parng of
elocuons wil ot occur If ping of elections ger, thn it will volt Hund’ re of maximum.
mall
PR
es goa
vee = CLOUD
vow e COC
O od
Es ition
‘esata
2. {Co (NO>)e1* ton: In his complex ion, oxidation stat of cobalt is + 2 and its valence shel
electronic configuration is 34. Magnetic moment measurements indicate that this complexion is
paramagnetic corresponding to presence of one unpsiredelecton. The NOF ligands are strong, they,
therefore, cause pring of metal 34 electors, Paling suggested that two vacant 3d orbitals are made
avale by promotion of an unpaired elton from a habil to Ssorbital so that Co? jon pots
À parie.
‘The presence of an unpiced électron in Soil supported by he fat that, s- orbital bas very
igh energy and the electron present in its sel bond and can he removed easly Experimental à
ds also observed that [Co(NO2)6 1°" is oxidized by ai or HO) easily to give [Co(NO7)g]”. This
indicates that the complex [Co(NO2 Js" is unstable in air. Ths, this complex should be prepared in
ines atmosphere.
Mt
Coam
bos
ES MENO
e EDAD O
(cunt in EEN (1 vase
Aprilia
gi
3.1Mn (CN) ion : In this complex ion, oxidation states of Ma is + 3 and ts valence shell
tectonic configuration is 34. Magnetic mess »ments show that his complex ion is paramagnetic
ning to two unpaired electrons. AI i o. electron occupy just thee ofthe five 3d orbitals
esving two 34: orbitals vacant, These two vacant 32- obits combine with he vaca 4 and dp-
bas give six dsp? «hybrid orbitals. These hybrid orbitals form bonds with igands by accepting
x pair of electrons, one pair ftom each of the six ligands, Since CN” isa strong ligand and has a
dency lo par up the d- electrons on metal but it causes pairing of two eleetons only leving two.
eons as unpaired, Lai the electrons become paired, hen wil volte the Hand's rule of maximum
ipl.
Maton
Bea
Mal ion
MEN) ion bgp hyhidization
«en ny
Soe, eme
in ide
4-ICE(CMGF om la this complex ion, oxidation ste of Ces + 3 and is valence shell
"tonic configuration is 34°. Magnetic measurement show tht this complex ion is
men is complex ion is paramagnetic
responding (the presence of three unpuiced electrons, AI the thee 3d ~ electrons occupy just hree
‘of te five 3d - orbitals Leaving two 3d obitals a vacant. These two vacant orbitals combine withthe
vacant 4s and 4p-ocitels to give six d?sp*-tybeid orbitals, These ix hybrid orbitals form bonds with
ligands by accepting six lone pair flgands, oe pi fiom each ofthe six ligands. The thre orbital of
the metal cation have thee unpaired electrons and are degenerate Thus, even inthe presence of strong
ligands pairing of electrons will not occu If paiingof electrons ocur, then it will violate Hund’ sale of
maximum multiplicity
o PR
en Too
Pon GERTDOCID
LCI ion
Ferien Faller
¿o ition
cata
‘SIV (NIls)¢]°* fom: In thiscoplex in, xico sico vanadium is + 3 nd is valence sell
cri coligustion is 142. Magnetic measurements indicat tht this complex ion i pramagnetic
coreponting o two unpaired econ, A he to 3d leas occupy just tuo of tke five 34 =
cab leaving the 34 orbital vacant wo of which combine wi vacat ds and ép orbitals o give
sx «hybrid obits. The dsp? hd ofits far bond wih he igands accepting sx pis
ofelectons, one pi rom each ofthe six ligan. Ou of three 34 uaybrdized orbitals, two oras
tae two unpaired electrons one unaired electron in each and one orbital remains vacant, These three
hybrid 34 - obials are degencae. Ths, evn inthe presence of tong ligands parng of
elocuons wil ot occur If ping of elections ger, thn it will volt Hund’ re of maximum.
mall
PR
es goa
vee = CLOUD
vow e COC
O od
Es ition
‘esata
A
A Re
Various ioner orbital octahedral complexes are state in Table 4 2.
48) Outer Orbital Octahedrat Complexes‘ Imourer orbital complexes the central metal cations
spd? -hybridized. Insp?d” hybridization, «orbital of outer shell (ie, nd - orbitals are involved, Let
- THEE 5 discuss complexes by taking some examples:
Eel dia (8) ICOFGA ion + In this complex ion, oxidation state of cobalt is + 3 and its valence hall
Complex Ton‘ } State of electronic configuration is 34°. Magnetic moment measurements show that this complex is
Metal ‘paramagnetic corresponding to four unpaired electrons. Also, F is a weak ligand, there will be no
ring 003 elecwons of theme cation Thus, theres no vacant 34-orbtaland none frías
valable to acoept elecron pars fromthe pda Consequently the vacant, 4 ad two ofthe fivedd
mo | +3 ut [sx F -orbitals combine to give six sp"? -hybidization. These hybrid orbitals form bonds by accepting six
> pairs of electrons, one | vom each of the six ligands.
el, à u Mow 4
engi rip ae, ree 2 ey MIND OOO
"in = FEET CA
¡Cr (H,0)5]% +3 34° [weak ii 'd’-bybcidization
Ka 3 (Cota? in (EIC jm; Fée)
pres Steep
Gap | +3 | 5 fons
4 @IFe (H20)s(NO)|"* ion: Inthiscomplex ion, oxidation state ofFeis+1 because NO exists in
+L oxidation state in complexes of Fe and its valence shell electronic configuration is 34° sl. Magnetic
nr | +2 | 6 am 3 (moment measurement of his comple in indicate ts experimental magro monat 5259 8M.
which comesponds 1 the unpird electos ia the complex ion, The sigle NO” song ind has
Tie tendency to pair up the electors i pais up only two unpaired electron, Since HO wea
7 A Tigand, therefore, I hs no tendery o alu the clins and non of he ve 34- rías is aca.
Biene | +2 | 3° [sm \ Therefore, he és, 4 and two ofthe Ave daa (Le. >,» ond dd à ) combine fo give 8
pare spd? hybrid orbitals. These hybrid orbitals form bonds with six Hgands by accepting six pairs of
A 2 2 2 elsezons oe par rom ech of hess Hands
SN 30° [tong em |
u da
E | strong di, CE) SRE UD
| parie Fein AO oo
[Fest +2 | 346 oN tn raion oy ios EINE ÉD épées
7 ‘ i
—_ NO" — strong. és -yoridzation Pita cie
Amor +4 sd8 | weak it
> o
VA Ep Arien
A Re
Various ioner orbital octahedral complexes are state in Table 4 2.
48) Outer Orbital Octahedrat Complexes‘ Imourer orbital complexes the central metal cations
spd? -hybridized. Insp?d” hybridization, «orbital of outer shell (ie, nd - orbitals are involved, Let
- THEE 5 discuss complexes by taking some examples:
Eel dia (8) ICOFGA ion + In this complex ion, oxidation state of cobalt is + 3 and its valence hall
Complex Ton‘ } State of electronic configuration is 34°. Magnetic moment measurements show that this complex is
Metal ‘paramagnetic corresponding to four unpaired electrons. Also, F is a weak ligand, there will be no
ring 003 elecwons of theme cation Thus, theres no vacant 34-orbtaland none frías
valable to acoept elecron pars fromthe pda Consequently the vacant, 4 ad two ofthe fivedd
mo | +3 ut [sx F -orbitals combine to give six sp"? -hybidization. These hybrid orbitals form bonds by accepting six
> pairs of electrons, one | vom each of the six ligands.
el, à u Mow 4
engi rip ae, ree 2 ey MIND OOO
"in = FEET CA
¡Cr (H,0)5]% +3 34° [weak ii 'd’-bybcidization
Ka 3 (Cota? in (EIC jm; Fée)
pres Steep
Gap | +3 | 5 fons
4 @IFe (H20)s(NO)|"* ion: Inthiscomplex ion, oxidation state ofFeis+1 because NO exists in
+L oxidation state in complexes of Fe and its valence shell electronic configuration is 34° sl. Magnetic
nr | +2 | 6 am 3 (moment measurement of his comple in indicate ts experimental magro monat 5259 8M.
which comesponds 1 the unpird electos ia the complex ion, The sigle NO” song ind has
Tie tendency to pair up the electors i pais up only two unpaired electron, Since HO wea
7 A Tigand, therefore, I hs no tendery o alu the clins and non of he ve 34- rías is aca.
Biene | +2 | 3° [sm \ Therefore, he és, 4 and two ofthe Ave daa (Le. >,» ond dd à ) combine fo give 8
pare spd? hybrid orbitals. These hybrid orbitals form bonds with six Hgands by accepting six pairs of
A 2 2 2 elsezons oe par rom ech of hess Hands
SN 30° [tong em |
u da
E | strong di, CE) SRE UD
| parie Fein AO oo
[Fest +2 | 346 oN tn raion oy ios EINE ÉD épées
7 ‘ i
—_ NO" — strong. és -yoridzation Pita cie
Amor +4 sd8 | weak it
> o
VA Ep Arien
Some outer orbital octhedal complexes ar illustrated in Table 43. + Tetrahodrai Complexes
Table 43 In erraheital complexes he metal cation is either por. -hybridied. Let us consider the some
example state e hybridization ad geometry
NI CU ion: His comple on, oxidation tt of is ais voce shel electron
configuration 34°. Magnet moment measurements indicate hui paramagnetic eomesponding to
(wo unpurdeetas Since CI isa weak ligand, cto, o pang of esas wi cer in 34-
‘otha. None ofthe five 3d ita is vacant, Vaca 4 and 4p-obitlseombie to give four =
Layo bals because {NCA i a tetrahedral complex on, These four hybrid orbitals form bonds
it for ligan y hing four aio electrons, one ai for each of th fou ligand.
“0%
E TAMA
Ni ion CARO CO
Ro is AE «Patria
es
D]
(@)Ni(CO)g + Inthis compound oxidation state of nickel is zero and is valence shell electronic
ER"
mat | +2 | set
—
MEA] +2 | 145
(Fer) A configuration is 34*45?, Magnetic moment measurements indicate that Ni(CO) is diamagnetic Le. it
ar +3 load DA 5 Bat no unpaiedelecrns. CO a stong ligand and has th tendeney to pair pt d-cetrons Dung
LFeB20) Po ns the pairing of electrons the two electrons of 4s-orbitals shift into one of the five 3¢- orbitals. Thus, there
isno vacant 34 orbital Tas, the vacant orbitals available for hybridization are A and 4p 1 give four
. Panel sp! yo oils.
(Corey 43 | 346 | weak Fees 4 u
Pis E BEA —
E = COUP in [DIET sp yriiztioa
icone | +2 | 57 | stone | MENÉS LOI | 3 gee Es ——
nenn pa
ZOO m: bi ge de a Mos De at de
po onfiguation of Ma is3d° 4s". In Ma jon all the five 34, 4-oibials are vacant. The vacan 4 a
wor | 42 | act 2 run a 4 4 Mal nal eve don a ie a nd
three 3d: orbitals combine o give fur sd -hybrid orbital, Thus, Ma”? ion iss - hybrid in his
pre complexion a shown below
Mos a
From te for going discusion itis cocluded that the otahedral complexes of d2,¢2- metal aay MI +
| sons ac avg ins al compl ver the ligands are we or song Tos cabal
‘complexes of dŸ, 4? and dl° mera) cations are always outer orbital ‘complexes either the ligands are
strong or weak, The complexes of d‘,d5,d® and d” metal cation
ligands ce weak i
Mion
BO in
Table 43 In erraheital complexes he metal cation is either por. -hybridied. Let us consider the some
example state e hybridization ad geometry
NI CU ion: His comple on, oxidation tt of is ais voce shel electron
configuration 34°. Magnet moment measurements indicate hui paramagnetic eomesponding to
(wo unpurdeetas Since CI isa weak ligand, cto, o pang of esas wi cer in 34-
‘otha. None ofthe five 3d ita is vacant, Vaca 4 and 4p-obitlseombie to give four =
Layo bals because {NCA i a tetrahedral complex on, These four hybrid orbitals form bonds
it for ligan y hing four aio electrons, one ai for each of th fou ligand.
“0%
E TAMA
Ni ion CARO CO
Ro is AE «Patria
es
D]
(@)Ni(CO)g + Inthis compound oxidation state of nickel is zero and is valence shell electronic
ER"
mat | +2 | set
—
MEA] +2 | 145
(Fer) A configuration is 34*45?, Magnetic moment measurements indicate that Ni(CO) is diamagnetic Le. it
ar +3 load DA 5 Bat no unpaiedelecrns. CO a stong ligand and has th tendeney to pair pt d-cetrons Dung
LFeB20) Po ns the pairing of electrons the two electrons of 4s-orbitals shift into one of the five 3¢- orbitals. Thus, there
isno vacant 34 orbital Tas, the vacant orbitals available for hybridization are A and 4p 1 give four
. Panel sp! yo oils.
(Corey 43 | 346 | weak Fees 4 u
Pis E BEA —
E = COUP in [DIET sp yriiztioa
icone | +2 | 57 | stone | MENÉS LOI | 3 gee Es ——
nenn pa
ZOO m: bi ge de a Mos De at de
po onfiguation of Ma is3d° 4s". In Ma jon all the five 34, 4-oibials are vacant. The vacan 4 a
wor | 42 | act 2 run a 4 4 Mal nal eve don a ie a nd
three 3d: orbitals combine o give fur sd -hybrid orbital, Thus, Ma”? ion iss - hybrid in his
pre complexion a shown below
Mos a
From te for going discusion itis cocluded that the otahedral complexes of d2,¢2- metal aay MI +
| sons ac avg ins al compl ver the ligands are we or song Tos cabal
‘complexes of dŸ, 4? and dl° mera) cations are always outer orbital ‘complexes either the ligands are
strong or weak, The complexes of d‘,d5,d® and d” metal cation
ligands ce weak i
Mion
BO in
In Mn” ion energy of vacant 4s-orbital becomes lower than that of vacant 3d- orbitals (aufbacu
principle)
ln sd? hybridization vacaat dy, dy and dx orbitals ae involved,
(9102 io à In his complex in, xian sat of Cri +6 and valence shell eee
‘configuration of Cr is 34° 4s!, Ce® ion has no electron in 3d- orbitals, The 4s - and three 3d - vacant
‘bis ofeeh i on combine to give ou sd hybrid oil. Ths exc” onin 07 omis
sd. hybridized. One of the seven oxide ions, shares both the Cr ions.
Pyridin
skoda
se byhidiion Lund
lus o unpaired electron, therefore, it is diamagnetic, Some tetrahedral complexes ar illustrated
in Tabled. =
Table 4.4
Oxidation Ino. of Unpaired
State Elétrons (m)
+2 3
[recy +2 4
{cu +2 as
Wu aa | 34° 2 1
{X=G1, Br" CNS") | Form
a > +
ar eo | 34° | CEO) eT o
beer arr] sae
| rien
‘Square Planar Complexes
Tn square planar complexes, the centra metal cion dp”. hybidized. The dp hybrid orbitals
point towards tbe four comers of a square.
Letus consider some examples to discuss the hybridization in square planar complexes
ICP” ion = in this complex ion, oxidation site of Ni is + 2 and its valence shell
electronic configuration is 34Ÿ. Magnetic moment measurement indicate (hat this complex jon is
diamagnetic, it has no unpaired electrons. Since CN” is a strong ligands, therefore, these ligands
‘cause to pairup the tuo unpaire electrons in one d orbital resuling na vacant orbital. This vacant
34 bal gets hybeidized withthe vacant 4s and two ofthe dporbial to give four dop?- hybrid
bias. These hybrid orbitals form bonds to the igands by accepting four pair of ligand electrons, one
ai fom each ofthe four igands
e e
ES MED
Ms EREEMOLLD
MP ion TETE +? iano
ag orion EY
OCA (Haya i
configuration is 34°. Magnetic moment mesuremens diate that this complex oni paramagnetic
corespondingto presence of one unpaired electron. There isn possibility of pring of electrons by the
Hard even te gan is song because there is only one urpuird elcron ia 34 - ovis. Since
coordination number of Cu* in in [Cu(NHa a + is 4, therefore, according to VRT, Cu ion should
ep hybrid and he sucre i traba om
ce Mu + A7
e Goon
02" on mrmnoon
ni ion, oxidation tte of eopperis +2 and valence shell electronic
Gt ion (EEE) Pinon
ar Aoi Fe
principle)
ln sd? hybridization vacaat dy, dy and dx orbitals ae involved,
(9102 io à In his complex in, xian sat of Cri +6 and valence shell eee
‘configuration of Cr is 34° 4s!, Ce® ion has no electron in 3d- orbitals, The 4s - and three 3d - vacant
‘bis ofeeh i on combine to give ou sd hybrid oil. Ths exc” onin 07 omis
sd. hybridized. One of the seven oxide ions, shares both the Cr ions.
Pyridin
skoda
se byhidiion Lund
lus o unpaired electron, therefore, it is diamagnetic, Some tetrahedral complexes ar illustrated
in Tabled. =
Table 4.4
Oxidation Ino. of Unpaired
State Elétrons (m)
+2 3
[recy +2 4
{cu +2 as
Wu aa | 34° 2 1
{X=G1, Br" CNS") | Form
a > +
ar eo | 34° | CEO) eT o
beer arr] sae
| rien
‘Square Planar Complexes
Tn square planar complexes, the centra metal cion dp”. hybidized. The dp hybrid orbitals
point towards tbe four comers of a square.
Letus consider some examples to discuss the hybridization in square planar complexes
ICP” ion = in this complex ion, oxidation site of Ni is + 2 and its valence shell
electronic configuration is 34Ÿ. Magnetic moment measurement indicate (hat this complex jon is
diamagnetic, it has no unpaired electrons. Since CN” is a strong ligands, therefore, these ligands
‘cause to pairup the tuo unpaire electrons in one d orbital resuling na vacant orbital. This vacant
34 bal gets hybeidized withthe vacant 4s and two ofthe dporbial to give four dop?- hybrid
bias. These hybrid orbitals form bonds to the igands by accepting four pair of ligand electrons, one
ai fom each ofthe four igands
e e
ES MED
Ms EREEMOLLD
MP ion TETE +? iano
ag orion EY
OCA (Haya i
configuration is 34°. Magnetic moment mesuremens diate that this complex oni paramagnetic
corespondingto presence of one unpaired electron. There isn possibility of pring of electrons by the
Hard even te gan is song because there is only one urpuird elcron ia 34 - ovis. Since
coordination number of Cu* in in [Cu(NHa a + is 4, therefore, according to VRT, Cu ion should
ep hybrid and he sucre i traba om
ce Mu + A7
e Goon
02" on mrmnoon
ni ion, oxidation tte of eopperis +2 and valence shell electronic
Gt ion (EEE) Pinon
ar Aoi Fe
se dein, sucesion ONE Ja is found
ut according to ESR and X-rys SUS on ar? hybride itis considered tha he unpaired
be square planar. Thus, to mike" 082: emcee
inthe 34 2 otitis to be prom we
dridco
ÉD suse
ae
pri"
«pete electron is present in tb Higher eneny Apr
Inthe above lesronie onfigurion. 9% Cu)" den may be easily orita ©
bil and is expected to be los asi *
a Re
wi qe ER He
BT EI" ion does not exist Le. oxidation of
Bu, examens sve town tat Ci.
Se pa
Tru (NEE at 10 (Cu NH sl” isnot (O(N) fan Cs ni pts
Firall Hogginsuggeted tains P
hor bow: ,
Ariza.
como pF Tee
a
tits Apra rias unytcidize e, does eat
In this configuration one of the three af ges above and below the plane ofthe ion Cu,
re planar 2 ion is
in rene es squeceplanar end Cu SS
LG CN comple ot o msi gen Tabl 45
cen ii dp,
PA
Bisa
(racy +2 4
aap yin
mau +2 ss | ARTE é
i tybridization
POR] 42 548 o
de adrien
Limitations of VET
1. Iteould not explain the nature ofligands Le, which ligand i strong and which one is weak
2. Iteauld not explain why the pairing of electrons ocur in he presence of strong ligands.
3. From this theory magnetic moment cn be calculated by knowing the number of unpaired electrons
butit could not explain the effect of timpertureon magnetie moment. could also net explain why
the experimental value of magnetic moments greater than the calculated in some complexes.
4. It could not explain the distortion in some octahedral complexes like [Cr(H20}¢]°* and
fue?
5. Ttcould not explain the colour and eecrani spot of complexes,
6. Iteould not explain reaction rates and mechanism of reactions of complexes.
7, Weoould not explein he structure of{Cu(NHs)g}* ion,
(2) Crystal Field Theory (CFT)
‘Valence bond theory is seat visualize the bndingin complexes but it ls to explain the nature
of ligands, colour and electronic spec, effet of temperature on magnetic moment and megnetc
suseptiblis, why some complexes re high spn and others ae [ow spin, stability of complexes Zo
explain these properties Bethe and van Vleck proposed the crystal Yield theory. This theory was
‘orginally applied to ionic crystal andi, therefore, called crystal Feld theory
“This theory i based on the following sumptions: ~
D lon Higands suchas C1" ,OH”,CN” are regarded as negative point charges (or simply port
charges) and he neutral ligands such as 0,8, py are regarded as point poe (or Si
poles) because these ligands ae diol IF the gard is neutral molecule lie EzO, Nts the
negative end of the dipole is directed toward’ the metal o:
few. eee
Sr Ne
ame)
ut according to ESR and X-rys SUS on ar? hybride itis considered tha he unpaired
be square planar. Thus, to mike" 082: emcee
inthe 34 2 otitis to be prom we
dridco
ÉD suse
ae
pri"
«pete electron is present in tb Higher eneny Apr
Inthe above lesronie onfigurion. 9% Cu)" den may be easily orita ©
bil and is expected to be los asi *
a Re
wi qe ER He
BT EI" ion does not exist Le. oxidation of
Bu, examens sve town tat Ci.
Se pa
Tru (NEE at 10 (Cu NH sl” isnot (O(N) fan Cs ni pts
Firall Hogginsuggeted tains P
hor bow: ,
Ariza.
como pF Tee
a
tits Apra rias unytcidize e, does eat
In this configuration one of the three af ges above and below the plane ofthe ion Cu,
re planar 2 ion is
in rene es squeceplanar end Cu SS
LG CN comple ot o msi gen Tabl 45
cen ii dp,
PA
Bisa
(racy +2 4
aap yin
mau +2 ss | ARTE é
i tybridization
POR] 42 548 o
de adrien
Limitations of VET
1. Iteould not explain the nature ofligands Le, which ligand i strong and which one is weak
2. Iteauld not explain why the pairing of electrons ocur in he presence of strong ligands.
3. From this theory magnetic moment cn be calculated by knowing the number of unpaired electrons
butit could not explain the effect of timpertureon magnetie moment. could also net explain why
the experimental value of magnetic moments greater than the calculated in some complexes.
4. It could not explain the distortion in some octahedral complexes like [Cr(H20}¢]°* and
fue?
5. Ttcould not explain the colour and eecrani spot of complexes,
6. Iteould not explain reaction rates and mechanism of reactions of complexes.
7, Weoould not explein he structure of{Cu(NHs)g}* ion,
(2) Crystal Field Theory (CFT)
‘Valence bond theory is seat visualize the bndingin complexes but it ls to explain the nature
of ligands, colour and electronic spec, effet of temperature on magnetic moment and megnetc
suseptiblis, why some complexes re high spn and others ae [ow spin, stability of complexes Zo
explain these properties Bethe and van Vleck proposed the crystal Yield theory. This theory was
‘orginally applied to ionic crystal andi, therefore, called crystal Feld theory
“This theory i based on the following sumptions: ~
D lon Higands suchas C1" ,OH”,CN” are regarded as negative point charges (or simply port
charges) and he neutral ligands such as 0,8, py are regarded as point poe (or Si
poles) because these ligands ae diol IF the gard is neutral molecule lie EzO, Nts the
negative end of the dipole is directed toward’ the metal o:
few. eee
Sr Ne
ame)
TERA
(2) Meta-igandbondisaot ment ie, teres no overlaping of orbitals, instead the booting io
complexes i purely lets nature. In complexes two ypesofetetosai Forces come
into account, One isthe attraction between te metal cation and the negatively har ligand or
the negative end ofthe polar ligand (Le, dipole), The second typeof electrostatic interactions
the electrostatic repusion between the lone pais of electrons on the igands andthe letronsin
the d: orbitals ofthe metal cation and the repulsion between nuclei of metal cation and the
figazds but toa small extent. An another repulsion lso comes into account hat occurs among,
the ligands
6) The five d-orbitalsina fee metal ionare degenerate (ie, have same energy) When a complex
is formed, he electrostatic fed ofthe ligands destroy the degeneracy ofthese dot Le,
these orbitals now have different energies. The orbital yng in the ctetion ofthe igands are
‘ised in energy more tha those ving aay rom the ligand because ofthe repulsion between
the d- electors and te gas
Taorder to understand the CT, ti neessary to know the geometry and orientations ofthe five
dors
Shape of dorbitals
APP
E A lelabeteen te mend
Mere a pudo y wd. Seon es
Jn so far as there are only five independent d - orbitals, one of them ( the d > ) is regarded as the
ier combina ed» ad as gue 42) bere ot a se o
cas have een ese
eK
das pS ES
NA surtt a à ol ls ie do
‘The orbital 2,2 has the probably finding electron slong the and axes voces he orbital
4.2. bas te probably of Sinn electron long and jaxes Therefore, when these two abia are
combined, the es d (od, 2 2. 2) xl has probability of finding electron along z-axis
twice that of along thes and y- ans. Ted abit also has some faction of probity along te 2
and y-axes. This component has doughnut shape (Le, ring shape), Therefor, the ive d-obials
Shown in Figure 4.3 ae dy dy dardo. ed.
do.
des de
Higure 43: Shapes and-oriearation o£d=orbitala,,
‘The three orbital dd and de li in between the axes, These three orbital le in 7, yz and zu
Planes respectively. Thed._othialonxand yanes andthe d 2 bia on 2axisThesbape of à
diferent from the other four.
Al the five d-obitels are gerade because Ihe opposite Isbes have inversion centre (Fe, centre
symmetcy) with respect to phase of wave functions. The plus (+) ard minus (- ) signs indicate
diféret phase ofthe lobes of orbital
Crystal Field Spiiting in Octahedral Complexes
In a re (or sole) mel cation al ie fie obits are degenerate (Le, these Hate sam
energy). la an ocabedal complex, say [MLG]"* the metal cation is placed a cette of the
‘ctahedson and the six ligands ar atthe six comers. These six comers are dircted along the catsian
coordinates Le, along x y and axes (Figure 4.4)
igure #4 Octal sucre of (ML on
‘When all the six ligands are at infinito distance from the metal cation, the five -obials of he fice
‘metal cation will not be affected by th ligand eletostari field and will remain degenerate, When the
ligand inove towords the metal cation, there are two electrostatic forces. One isthe action betwee
(2) Meta-igandbondisaot ment ie, teres no overlaping of orbitals, instead the booting io
complexes i purely lets nature. In complexes two ypesofetetosai Forces come
into account, One isthe attraction between te metal cation and the negatively har ligand or
the negative end ofthe polar ligand (Le, dipole), The second typeof electrostatic interactions
the electrostatic repusion between the lone pais of electrons on the igands andthe letronsin
the d: orbitals ofthe metal cation and the repulsion between nuclei of metal cation and the
figazds but toa small extent. An another repulsion lso comes into account hat occurs among,
the ligands
6) The five d-orbitalsina fee metal ionare degenerate (ie, have same energy) When a complex
is formed, he electrostatic fed ofthe ligands destroy the degeneracy ofthese dot Le,
these orbitals now have different energies. The orbital yng in the ctetion ofthe igands are
‘ised in energy more tha those ving aay rom the ligand because ofthe repulsion between
the d- electors and te gas
Taorder to understand the CT, ti neessary to know the geometry and orientations ofthe five
dors
Shape of dorbitals
APP
E A lelabeteen te mend
Mere a pudo y wd. Seon es
Jn so far as there are only five independent d - orbitals, one of them ( the d > ) is regarded as the
ier combina ed» ad as gue 42) bere ot a se o
cas have een ese
eK
das pS ES
NA surtt a à ol ls ie do
‘The orbital 2,2 has the probably finding electron slong the and axes voces he orbital
4.2. bas te probably of Sinn electron long and jaxes Therefore, when these two abia are
combined, the es d (od, 2 2. 2) xl has probability of finding electron along z-axis
twice that of along thes and y- ans. Ted abit also has some faction of probity along te 2
and y-axes. This component has doughnut shape (Le, ring shape), Therefor, the ive d-obials
Shown in Figure 4.3 ae dy dy dardo. ed.
do.
des de
Higure 43: Shapes and-oriearation o£d=orbitala,,
‘The three orbital dd and de li in between the axes, These three orbital le in 7, yz and zu
Planes respectively. Thed._othialonxand yanes andthe d 2 bia on 2axisThesbape of à
diferent from the other four.
Al the five d-obitels are gerade because Ihe opposite Isbes have inversion centre (Fe, centre
symmetcy) with respect to phase of wave functions. The plus (+) ard minus (- ) signs indicate
diféret phase ofthe lobes of orbital
Crystal Field Spiiting in Octahedral Complexes
In a re (or sole) mel cation al ie fie obits are degenerate (Le, these Hate sam
energy). la an ocabedal complex, say [MLG]"* the metal cation is placed a cette of the
‘ctahedson and the six ligands ar atthe six comers. These six comers are dircted along the catsian
coordinates Le, along x y and axes (Figure 4.4)
igure #4 Octal sucre of (ML on
‘When all the six ligands are at infinito distance from the metal cation, the five -obials of he fice
‘metal cation will not be affected by th ligand eletostari field and will remain degenerate, When the
ligand inove towords the metal cation, there are two electrostatic forces. One isthe action betwee
fl con gs nd ud eos epson ven eto con
ane de Gear feo amin bee eo a me
a ll Umm cc be el con ed ee wae ete unes
dato ant one par of cos. When te panda br he el ton
ee cana non he pds. These o eps cae et él
raat gst ined gc on mean nd pet om
ne Te feof pin Been met tees ne lips cs
a en para! egy fe mel lc. Reni dt gs de emo o
ne Il ira e essed
ct tner, dept qua sec om ect dais Tee
em el wi ab be ae swt nal re ati wl aia
eee tint appeal sonda he ene ers feo i anal
acon ey nel ave ci. Tenor al ete die
amd oa Sc ls o hal,» ad) dci os eas
dnd dencre tn! pci pod Ter de
D de os erro tn pl ed, ste
tag? stands oie bed ha ofen ave ve fom
een raie cong ate gee) Tee Za ick
ca a pitino sso ron cgi ae
Sp wh yp an) ving ese es wee wih te
scm rb eed MA) Teste yp add y oia reads ich
a es tty mi hal red a ah py
oa
| Arge u
| | HER
| Fromme deta orten ‘
| RE En ei
Figure 45,
Since he distance between the metal cation and the ligands has remaied he seme, the net potential
energy (or average energy ofthe system must remain the same as tat of the spherical feld before
spliting, This state of average energy is called the baryoenter
The separation of five c-abial of metal cation into wo set of different energies is called crystal
‘ied splicing, The ergy difference between two sets of orbital which aise from an octahedral e is
measured in terms of the parameter Ay of 10 Dg, where o in À, stands for octahedral
Since te energy oftasycentre remains constant the total energy decrease oft set must be equal to
‘he coral energy increase of ey set. Therefore, since there are two e, oia, they mus! increase by 0.6
A or 6a e eg inst dose 3 04 oF D pe etn. Ti et in
energy of fg otbitals stabilizes the complex by 04 A, and the incteae in energy of eg orbitals
estabilizes the complex by 06 Ag.
Crystal Field Spliting in Tetrahedral Complexes
A regular tetrahedral geomoty is obtained when a metal cation or stom spaced at the centre oa
Cube and four ligands oocupy the alternate comers ofthe cube as shown in Figue 46
Bitar 44cTerandeal srangemen of four ligands sound e mea oni cubo.
‘The x,y and x axes ate passed through the centres ofthe faces ofthe cube. None ofthe ligando
_appcoach directly any ofthe metal orbitals, Instead they all approach 10 some degre in between the
met orbita
Man eee ome Figure 47 ha the thre ob (dd y, add) ae frs (05)
Tem sto nt ca cy
(0.71, br ise eng ofthe sid ofthe cube berne, we ca td, dz addy
area 1) os frase sisters hd. oa nl
af tester
}
An
and) boto those dicto be cetes the cube (ie, da, and). Fath oft fved- obits
in terahedral field represented i Figure 4.7.
———
ane de Gear feo amin bee eo a me
a ll Umm cc be el con ed ee wae ete unes
dato ant one par of cos. When te panda br he el ton
ee cana non he pds. These o eps cae et él
raat gst ined gc on mean nd pet om
ne Te feof pin Been met tees ne lips cs
a en para! egy fe mel lc. Reni dt gs de emo o
ne Il ira e essed
ct tner, dept qua sec om ect dais Tee
em el wi ab be ae swt nal re ati wl aia
eee tint appeal sonda he ene ers feo i anal
acon ey nel ave ci. Tenor al ete die
amd oa Sc ls o hal,» ad) dci os eas
dnd dencre tn! pci pod Ter de
D de os erro tn pl ed, ste
tag? stands oie bed ha ofen ave ve fom
een raie cong ate gee) Tee Za ick
ca a pitino sso ron cgi ae
Sp wh yp an) ving ese es wee wih te
scm rb eed MA) Teste yp add y oia reads ich
a es tty mi hal red a ah py
oa
| Arge u
| | HER
| Fromme deta orten ‘
| RE En ei
Figure 45,
Since he distance between the metal cation and the ligands has remaied he seme, the net potential
energy (or average energy ofthe system must remain the same as tat of the spherical feld before
spliting, This state of average energy is called the baryoenter
The separation of five c-abial of metal cation into wo set of different energies is called crystal
‘ied splicing, The ergy difference between two sets of orbital which aise from an octahedral e is
measured in terms of the parameter Ay of 10 Dg, where o in À, stands for octahedral
Since te energy oftasycentre remains constant the total energy decrease oft set must be equal to
‘he coral energy increase of ey set. Therefore, since there are two e, oia, they mus! increase by 0.6
A or 6a e eg inst dose 3 04 oF D pe etn. Ti et in
energy of fg otbitals stabilizes the complex by 04 A, and the incteae in energy of eg orbitals
estabilizes the complex by 06 Ag.
Crystal Field Spliting in Tetrahedral Complexes
A regular tetrahedral geomoty is obtained when a metal cation or stom spaced at the centre oa
Cube and four ligands oocupy the alternate comers ofthe cube as shown in Figue 46
Bitar 44cTerandeal srangemen of four ligands sound e mea oni cubo.
‘The x,y and x axes ate passed through the centres ofthe faces ofthe cube. None ofthe ligando
_appcoach directly any ofthe metal orbitals, Instead they all approach 10 some degre in between the
met orbita
Man eee ome Figure 47 ha the thre ob (dd y, add) ae frs (05)
Tem sto nt ca cy
(0.71, br ise eng ofthe sid ofthe cube berne, we ca td, dz addy
area 1) os frase sisters hd. oa nl
af tester
}
An
and) boto those dicto be cetes the cube (ie, da, and). Fath oft fved- obits
in terahedral field represented i Figure 4.7.
———
HT ios Chia
Figure At,
apr piton id
pe enr peer sus ety
mar hepa ae
de à a ie ion centre. The difference in energy of e and 17 sets is
Jeans, ae eat eed ine ema ae
shown Figure 44, oma
The crystal field spliing is just reverse of the octahedral compl
os" nn Omi
en ven ent
Es
Eres Gel ies rectal oles,
#18
(9 None of he ligands point directly towards an ofthe five dot Therefore, the splitting i
redee by roughly two tied tn tetrahedral and octahedral complexes the 4, dye and dy orbitals
ae a o Le at qual distance fom the gus, There, in bth the comple can ligand
sce es ral in egal amount. octal completes, ligando approach directly to
% of zontal and ep them soni. Baia ether ones hen eb an a
711 Gt aproxiatly equal to th 20) a compare tht o oc complexes,
‘erst teme! comple, th Has eel hse iss 2 ines tan bat of
dal complexes. Ths, det thi ft, siting deca by din aaa complexes
AS compare to octahedral complexes.
The, by = Faden, CREER
5
Fetbedrlcomplenes ae always high spin because :() A,
Je Le, A, is muck smaller than
ae and i i lay ess tan pig exer. De o these two reasons no
Pai of eeeons oa ind," 45,4 and taba camp, Therefore, he tetrahedral
<omplees ofthese coniguratins ar always high spin wheter the ind xe strang or weak,
Factors Affecting the Magnitude of 4
‘Thee ae several factors that affect the magnitude oF pling (4) ofa. érbal bythe surrounding
ligands. E
(0 Orton Stato the Meat Cation: The ghee xan an of te mea air, the
eter vil be th ag
cir ovation state of the metal causes the Hands to appeach me closely to it and,
therefore, ligands cause more sping of metal d- obits Fos cramp,
A, for (Co(t20)6)** =9200 en
andy ferfCo(tt.0)«}>* = 20760 o
£2) Same Oran State of Metal Cation but the Number of écrans i Different : ln
ara Be ses fan tennis (y 24- sers ia co having the metal cation
Far(Co(tOrei"*, 8, =9200em (u)
For[NiRO)6P", à, =8500cm" 43)
Figure At,
apr piton id
pe enr peer sus ety
mar hepa ae
de à a ie ion centre. The difference in energy of e and 17 sets is
Jeans, ae eat eed ine ema ae
shown Figure 44, oma
The crystal field spliing is just reverse of the octahedral compl
os" nn Omi
en ven ent
Es
Eres Gel ies rectal oles,
#18
(9 None of he ligands point directly towards an ofthe five dot Therefore, the splitting i
redee by roughly two tied tn tetrahedral and octahedral complexes the 4, dye and dy orbitals
ae a o Le at qual distance fom the gus, There, in bth the comple can ligand
sce es ral in egal amount. octal completes, ligando approach directly to
% of zontal and ep them soni. Baia ether ones hen eb an a
711 Gt aproxiatly equal to th 20) a compare tht o oc complexes,
‘erst teme! comple, th Has eel hse iss 2 ines tan bat of
dal complexes. Ths, det thi ft, siting deca by din aaa complexes
AS compare to octahedral complexes.
The, by = Faden, CREER
5
Fetbedrlcomplenes ae always high spin because :() A,
Je Le, A, is muck smaller than
ae and i i lay ess tan pig exer. De o these two reasons no
Pai of eeeons oa ind," 45,4 and taba camp, Therefore, he tetrahedral
<omplees ofthese coniguratins ar always high spin wheter the ind xe strang or weak,
Factors Affecting the Magnitude of 4
‘Thee ae several factors that affect the magnitude oF pling (4) ofa. érbal bythe surrounding
ligands. E
(0 Orton Stato the Meat Cation: The ghee xan an of te mea air, the
eter vil be th ag
cir ovation state of the metal causes the Hands to appeach me closely to it and,
therefore, ligands cause more sping of metal d- obits Fos cramp,
A, for (Co(t20)6)** =9200 en
andy ferfCo(tt.0)«}>* = 20760 o
£2) Same Oran State of Metal Cation but the Number of écrans i Different : ln
ara Be ses fan tennis (y 24- sers ia co having the metal cation
Far(Co(tOrei"*, 8, =9200em (u)
For[NiRO)6P", à, =8500cm" 43)
(65) Principal Quantum Number (1) ofthe orbital ofthe Metal Cation : In case of complexes
saving the metal cations with sedation sats ard ane number od clecrons, the magnitude of
for analogous complexes within a given group increase about 30% o 50% from 3 1 dd and by about
ie same amount from 4d to $e tis because
(i) On moving 34 to dd and to Sd te size of the d- orbitals increases and electron density
ecreases in them. Therefore, the Hands can approach he metal ation wit lage de oia
more closely.
(i) There is es teri hindrance rund age mea cation
For example : For (Co(NH3)6]°*, 4, = 23000 cas
For{Rh(NH 6)", 6, = 34100"
For NH) PA =41200ca"*
{9 Nature of Ligands : The lgand ar cl a weak and strong ligands. The ligands which
a smli degree of spliting of d- bas ar call weskligundsand te ligands which cause arg
ing ar called strong ligands. The couse gand have been aranged in order of ir increasing,
stal field splitting power to cause splitting of orbitals from a study of their effects on the spectra of
sition metal ions,
F< Br” <S*< SCN" <CI<Nj <P" cuen <OH <CHHOH<C20Ë <
0? < H20 <NCS” < gly < NH3, py<en, SO" <NHZOH<bpy, phen<
< NO} <CHG, CgH3 < R3P<CN™ <CO
‘Tis order is usualy called as spctrach sal eri,
“Theorder ofthe fil teng of he common nds independent ofthe nature of the meta cation
fe the geomety ofthe comple
(5) Number of Ligands : The magnitude of. ald ping (A increases with increas of the
mb of ligands. For example, > By
‘Though number aigu in square plana comple sal than tat ofoctahedrlcompless,
magnitude of y is rete than. ie becas torta quae plana complexes are formed
Iy much strong ligands with d°= mal cation of d- series transition metals cation and 4d or 5d series
® ransition metal eation with ether weak orstrong ligands, The very strong ligands and 4d or Sd series
fusion metal cations are responsible fr iger crystal fell sping. Alo, in square planar
wnpexes of 2%. metal cations, the dz oil wit two clon is stabilized andthe vacant 7
tal is destabilize.
rystal Field Splitting in-Lanthanoid Complexes
‘The seven f orbials of lathanofds in their otahdral complexes are also split like dosis of
sition metal complexes. The ental el pling off cb is smaller than that of d- orbitals in
tahedral complexes. The 4f orbitals are buried in dep, therfore, the ligands can not approach close
po o Mhe4f orbital to cause much rytl field spliting. D
| par?
Distribution of c-electrons in Octahedral Complex
Thedistibtion of ¢-elecronsia ta ande oi depends upon the magnitude oy. When the
magnitude, isrlatvly smal etica tata te Ged ota Ce os ando, sj
dem (hare ame exc), db cion ad yn he ps
cording to Mund's rule of maximum multiplen e. pag of electrons sl tale place arly when
cach of ive d orig I singly file. Tes, in Sampler Korg anal alu of 2 be Teen
(on cco) bn So Sony re hard as
ce ag oil andthe ato cron an 10h copy te ral isc
me
nd, 30, O, ou
Ant $45, aan, man
Totes complees o pa electos wies place Le, arangenent of len ren
res ee meta cn
The competes in which he maid of le, ers of gan yb ite
sila ando distin elotes ng and, ea dos a Sey and nee
‘acinus Wes cols te fsx nt oops the, obit and he
remit fu ctor ce hee oils Tas oia
DAA PM A
a i
In these complexes the pairing of electrons takes place in fay anbitals for 4 ,d3,4S and 47
configura. Whete he ve of 4, i sl ar ge, hei o ference in ed con
configuration ford", d?,d?, d°, 4° anda" systems ie, foc these System there is no pairing ofelectran
inocahdr comport
‘Weak Field (or Ligand) or High Spin or Spin Free Compiexes
In weak feld octahedral complexes of ses tansition metas with oxidation number $43, he
‘valu off is small and there wil be no ping of electrons. Theredor, in the weak field complexes
ofd* d°,df and d? configuration, there is roping of electrons. These complexes have maximun
tuber of unpaired electrons. These complexes having maximum number of anpaired elec ase +
called high spin or sin fee complexes. The tem high spinor pin fre is used because these conplexes
Have same number of spin as ind» orbitals of fee metal ations.
Strong Field (or Ligand) or Low Spin or Spin Paired Complexes
In strong field octahedral complexes of 3d: series transition metals with oxidation number, in
general +2, the value ofA is large. Inthe strong field complexes of, 5,4% and d configurations
pairing of d- electrons will take place in fag orbitals according to Hond's rule, These complexes having
maximum number of paired electrons are called low spin or spin paired complexes. The term low spin ot
spin pied is used because thse complexes have remuer of pred electons (or sin) tan stot
fre metal cations.
liso be noted hat weak field otaedal complexes always are not the high spin complexes. The
metal eatin of 3-anstion series wi oxidation number of + and the and Serios ar io
‚metal cations always form low spin complexes with weak ligands, For cxample,(Ni Fc ion oxidation
saving the metal cations with sedation sats ard ane number od clecrons, the magnitude of
for analogous complexes within a given group increase about 30% o 50% from 3 1 dd and by about
ie same amount from 4d to $e tis because
(i) On moving 34 to dd and to Sd te size of the d- orbitals increases and electron density
ecreases in them. Therefore, the Hands can approach he metal ation wit lage de oia
more closely.
(i) There is es teri hindrance rund age mea cation
For example : For (Co(NH3)6]°*, 4, = 23000 cas
For{Rh(NH 6)", 6, = 34100"
For NH) PA =41200ca"*
{9 Nature of Ligands : The lgand ar cl a weak and strong ligands. The ligands which
a smli degree of spliting of d- bas ar call weskligundsand te ligands which cause arg
ing ar called strong ligands. The couse gand have been aranged in order of ir increasing,
stal field splitting power to cause splitting of orbitals from a study of their effects on the spectra of
sition metal ions,
F< Br” <S*< SCN" <CI<Nj <P" cuen <OH <CHHOH<C20Ë <
0? < H20 <NCS” < gly < NH3, py<en, SO" <NHZOH<bpy, phen<
< NO} <CHG, CgH3 < R3P<CN™ <CO
‘Tis order is usualy called as spctrach sal eri,
“Theorder ofthe fil teng of he common nds independent ofthe nature of the meta cation
fe the geomety ofthe comple
(5) Number of Ligands : The magnitude of. ald ping (A increases with increas of the
mb of ligands. For example, > By
‘Though number aigu in square plana comple sal than tat ofoctahedrlcompless,
magnitude of y is rete than. ie becas torta quae plana complexes are formed
Iy much strong ligands with d°= mal cation of d- series transition metals cation and 4d or 5d series
® ransition metal eation with ether weak orstrong ligands, The very strong ligands and 4d or Sd series
fusion metal cations are responsible fr iger crystal fell sping. Alo, in square planar
wnpexes of 2%. metal cations, the dz oil wit two clon is stabilized andthe vacant 7
tal is destabilize.
rystal Field Splitting in-Lanthanoid Complexes
‘The seven f orbials of lathanofds in their otahdral complexes are also split like dosis of
sition metal complexes. The ental el pling off cb is smaller than that of d- orbitals in
tahedral complexes. The 4f orbitals are buried in dep, therfore, the ligands can not approach close
po o Mhe4f orbital to cause much rytl field spliting. D
| par?
Distribution of c-electrons in Octahedral Complex
Thedistibtion of ¢-elecronsia ta ande oi depends upon the magnitude oy. When the
magnitude, isrlatvly smal etica tata te Ged ota Ce os ando, sj
dem (hare ame exc), db cion ad yn he ps
cording to Mund's rule of maximum multiplen e. pag of electrons sl tale place arly when
cach of ive d orig I singly file. Tes, in Sampler Korg anal alu of 2 be Teen
(on cco) bn So Sony re hard as
ce ag oil andthe ato cron an 10h copy te ral isc
me
nd, 30, O, ou
Ant $45, aan, man
Totes complees o pa electos wies place Le, arangenent of len ren
res ee meta cn
The competes in which he maid of le, ers of gan yb ite
sila ando distin elotes ng and, ea dos a Sey and nee
‘acinus Wes cols te fsx nt oops the, obit and he
remit fu ctor ce hee oils Tas oia
DAA PM A
a i
In these complexes the pairing of electrons takes place in fay anbitals for 4 ,d3,4S and 47
configura. Whete he ve of 4, i sl ar ge, hei o ference in ed con
configuration ford", d?,d?, d°, 4° anda" systems ie, foc these System there is no pairing ofelectran
inocahdr comport
‘Weak Field (or Ligand) or High Spin or Spin Free Compiexes
In weak feld octahedral complexes of ses tansition metas with oxidation number $43, he
‘valu off is small and there wil be no ping of electrons. Theredor, in the weak field complexes
ofd* d°,df and d? configuration, there is roping of electrons. These complexes have maximun
tuber of unpaired electrons. These complexes having maximum number of anpaired elec ase +
called high spin or sin fee complexes. The tem high spinor pin fre is used because these conplexes
Have same number of spin as ind» orbitals of fee metal ations.
Strong Field (or Ligand) or Low Spin or Spin Paired Complexes
In strong field octahedral complexes of 3d: series transition metals with oxidation number, in
general +2, the value ofA is large. Inthe strong field complexes of, 5,4% and d configurations
pairing of d- electrons will take place in fag orbitals according to Hond's rule, These complexes having
maximum number of paired electrons are called low spin or spin paired complexes. The term low spin ot
spin pied is used because thse complexes have remuer of pred electons (or sin) tan stot
fre metal cations.
liso be noted hat weak field otaedal complexes always are not the high spin complexes. The
metal eatin of 3-anstion series wi oxidation number of + and the and Serios ar io
‚metal cations always form low spin complexes with weak ligands, For cxample,(Ni Fc ion oxidation
sate ENG is +4) sow spin and diamagncti, though F” 5 a weak ligand. (Rh (H20)¢]"* is low spin
and dismagneti though HO sa weak ligand. An exception is observed fr 4. series transition metals
in which Co™ forms low spin complexes with H¿0azd0”, though HOandO* are the weak gens.
Pairing Energy
‘The energy required to force he two unpaired electrons in one orbital is called the pring energy.
‘When more than one electrons ar paired, P becomes the mean pairing energy. It may be obtained
from the analysis of electronic spectra.
114, >P, it favours te low spin complexes,
154, < P, a ivours the high pin complexes,
fA, =P, high spin and low spin complexes equally exist.
In general, for4d-and Sd. series tanstion metal complexes, magnitude of gi reten tbat of P.
Distribution of & electrons in Tetrahedral Complexes
‘The magnitude of A, interahedral complexes is very small. Therefore its considered that energy
fe aná tz orbitalsis nearly sume, both the eand ‘sets are degenerate. Distribution ofd-clesronsin.
“aná z oritls will ke place according to Hund’ rule ¡e pairing of electron wil take place only
‘when each of the five d- orbitals singly occupied. The frst two electrons occupy thee orbital ra, th
and Sth electos occupy the 1 oils, 6th and Uh electron occupy the e-rbitals and the last three
electrons will oceupy the f obits. Ian be shown as
onl, fé, 0.9800
usas,
Far tarahdrl complets, y <P.
‘Crystal Field Stabilization Energy in Octahedral Complexes
In an octal comple, the dnl ofthe metal ction are split into two sts of diet
enorges, 2 fer cry ade fbighe energy. The separation between thee vo sets galo
4g ($109). The ng sh energy of- 04.84 (<= 4 Dg) and thee set hasancrorgyof +06
-+6 Dg) relative tothe biyoeäte. Mis ( and plus (+ ) signs indicate decrease and increase in
energy reve 1 he brete spectively. The complex fon with one een in ne of he 3,
orbitals has an energy of -0.4 A relive tthe barycenter. This indicates tatin complex ion of dl.
configuration 0.4 Ay energy is ele, Th release energy i called the rl id liza
enengy (CESE) ofthe compe on.
For dl complex, élecironie ist! e),
Ford! compis deco cons, €
CRSE=-04x 14-048,
Ford? con dci cnfguonis 2, 2
CESE=-04X24,=-084,
Ford? compis dci confus}, 2.
CFSE=-04%3.45=-124,,
Ford high in comple, ali oniguation is e
CESE =-04x3+06x18,=-064,
4° big spin complex wth electronic configuration ¿£, ef.
s CESE=[-04p+069)4,
Since no ping of lero ocu high sin complexe, 0 ping neg à
inv pi igh spin complexes, tree, no ping energy i
Foro spincomplewesotd® fd anda” meat ion, ping of leon cei él. To
rir up de two less nee am xr energy Is og which scalp
require which called paiing energy (P).
irn, frágiles, rai conga sl, 42
CSER[-04x8+06x0]A, +P
, --158,+P
Ferd lp comp, cn fun}, 2 ts cas fl rico
air up into ice ls of, e
Therefore, CESE={-04 54060], 427
=-294, 12?
Ford low in cabal comple with leone conga, ef
CFSE =[-04p+06 4914, + mp
acte pani ate sumer of etai ay and e abil resp.
m= Number fair a ton cased by he ge
is the mean psig cg The ried ang cc is compensated Som CSE.
Let un sie dis cla of CESE of some high spin and low in conplees,
(Ford® hgh gro engins cf. el.
CFSE [-04p+06 445
DATENT EE TA
. 2-044,
In his case, 0 puig ce In because no pang of electron scat by thie.
‘Though thas one paroles butts ot cased by the ligand. This pai was already preset
asbl a own below ny te ligan, Tas ps y present ind
‘Thus, for
arılıTı]ı
nn de Gr
Ford® low pin oad conte cons cotgution iff.
CFSE=[=04%6+06%0)4, +28
244,422
and dismagneti though HO sa weak ligand. An exception is observed fr 4. series transition metals
in which Co™ forms low spin complexes with H¿0azd0”, though HOandO* are the weak gens.
Pairing Energy
‘The energy required to force he two unpaired electrons in one orbital is called the pring energy.
‘When more than one electrons ar paired, P becomes the mean pairing energy. It may be obtained
from the analysis of electronic spectra.
114, >P, it favours te low spin complexes,
154, < P, a ivours the high pin complexes,
fA, =P, high spin and low spin complexes equally exist.
In general, for4d-and Sd. series tanstion metal complexes, magnitude of gi reten tbat of P.
Distribution of & electrons in Tetrahedral Complexes
‘The magnitude of A, interahedral complexes is very small. Therefore its considered that energy
fe aná tz orbitalsis nearly sume, both the eand ‘sets are degenerate. Distribution ofd-clesronsin.
“aná z oritls will ke place according to Hund’ rule ¡e pairing of electron wil take place only
‘when each of the five d- orbitals singly occupied. The frst two electrons occupy thee orbital ra, th
and Sth electos occupy the 1 oils, 6th and Uh electron occupy the e-rbitals and the last three
electrons will oceupy the f obits. Ian be shown as
onl, fé, 0.9800
usas,
Far tarahdrl complets, y <P.
‘Crystal Field Stabilization Energy in Octahedral Complexes
In an octal comple, the dnl ofthe metal ction are split into two sts of diet
enorges, 2 fer cry ade fbighe energy. The separation between thee vo sets galo
4g ($109). The ng sh energy of- 04.84 (<= 4 Dg) and thee set hasancrorgyof +06
-+6 Dg) relative tothe biyoeäte. Mis ( and plus (+ ) signs indicate decrease and increase in
energy reve 1 he brete spectively. The complex fon with one een in ne of he 3,
orbitals has an energy of -0.4 A relive tthe barycenter. This indicates tatin complex ion of dl.
configuration 0.4 Ay energy is ele, Th release energy i called the rl id liza
enengy (CESE) ofthe compe on.
For dl complex, élecironie ist! e),
Ford! compis deco cons, €
CRSE=-04x 14-048,
Ford? con dci cnfguonis 2, 2
CESE=-04X24,=-084,
Ford? compis dci confus}, 2.
CFSE=-04%3.45=-124,,
Ford high in comple, ali oniguation is e
CESE =-04x3+06x18,=-064,
4° big spin complex wth electronic configuration ¿£, ef.
s CESE=[-04p+069)4,
Since no ping of lero ocu high sin complexe, 0 ping neg à
inv pi igh spin complexes, tree, no ping energy i
Foro spincomplewesotd® fd anda” meat ion, ping of leon cei él. To
rir up de two less nee am xr energy Is og which scalp
require which called paiing energy (P).
irn, frágiles, rai conga sl, 42
CSER[-04x8+06x0]A, +P
, --158,+P
Ferd lp comp, cn fun}, 2 ts cas fl rico
air up into ice ls of, e
Therefore, CESE={-04 54060], 427
=-294, 12?
Ford low in cabal comple with leone conga, ef
CFSE =[-04p+06 4914, + mp
acte pani ate sumer of etai ay and e abil resp.
m= Number fair a ton cased by he ge
is the mean psig cg The ried ang cc is compensated Som CSE.
Let un sie dis cla of CESE of some high spin and low in conplees,
(Ford® hgh gro engins cf. el.
CFSE [-04p+06 445
DATENT EE TA
. 2-044,
In his case, 0 puig ce In because no pang of electron scat by thie.
‘Though thas one paroles butts ot cased by the ligand. This pai was already preset
asbl a own below ny te ligan, Tas ps y present ind
‘Thus, for
arılıTı]ı
nn de Gr
Ford® low pin oad conte cons cotgution iff.
CFSE=[=04%6+06%0)4, +28
244,422
AR
REE
SBN cla Bont Cp
y 425
Ta his use there are thre pai of electrons but only two are caused by de ligands and one veas
already present in d+ or 3
vest tee en
Mersch oye omis
‘The CFSE's of! to” high spin and low spin complexes sr given in Table 46.
Table 48 : CFSE Values for Octahedral Complexes of d to d" Metal Cations
qa Tih avn
det EL Chan
Crystal Field Stabilization Energy in Tetrahedral Complexes
An a toraedrel comple, the de orbitals ofthe meal con ar split into two st of different
eras, coflowe energy and ofhighe energy. The seperation betwena hese vo eis sequal io À
Theescthasaneneayof-06 8, andthe 1, sethas an enemy of + 04 Ay reliveto the bryecare. For
24" tera complex with e? ef configuration,
CPSE=[-06p+04g ja,
ETAT ETS Esas)
-027p+0.8gA,
‘Since erabdal complexes are high pin and no paring of electrons vcurs (A, <P) Therefore,
‘no pring energy is included in the above equation. The CFSE values of tetrahedra complexes o£d! to
dl meal ion given in Table 47
# ‘Table 47 : CFSE Values for Tetrahedral Complexes
er E
de “028,
q en 0544,
8 ad 0368,
a ee DIA,
a en o
# en -0274,
e “e -05t4,
é es 0364,
2 ad -0184,
a ee o
Tetragonal Distortion or Jahn-Teller Distortion
‘The six coord competes in wich al the si ines between meta con and de ligan
are same and sid be reglroohedal complexes, A compen wil be lr cta whe he
leon amngemenin ande obs ssymneric (Le, tah ante, bisa loci
non depart) Ii baste o the fc tat metal range ecto wil ee al cr
ligands equal.
REE
SBN cla Bont Cp
y 425
Ta his use there are thre pai of electrons but only two are caused by de ligands and one veas
already present in d+ or 3
vest tee en
Mersch oye omis
‘The CFSE's of! to” high spin and low spin complexes sr given in Table 46.
Table 48 : CFSE Values for Octahedral Complexes of d to d" Metal Cations
qa Tih avn
det EL Chan
Crystal Field Stabilization Energy in Tetrahedral Complexes
An a toraedrel comple, the de orbitals ofthe meal con ar split into two st of different
eras, coflowe energy and ofhighe energy. The seperation betwena hese vo eis sequal io À
Theescthasaneneayof-06 8, andthe 1, sethas an enemy of + 04 Ay reliveto the bryecare. For
24" tera complex with e? ef configuration,
CPSE=[-06p+04g ja,
ETAT ETS Esas)
-027p+0.8gA,
‘Since erabdal complexes are high pin and no paring of electrons vcurs (A, <P) Therefore,
‘no pring energy is included in the above equation. The CFSE values of tetrahedra complexes o£d! to
dl meal ion given in Table 47
# ‘Table 47 : CFSE Values for Tetrahedral Complexes
er E
de “028,
q en 0544,
8 ad 0368,
a ee DIA,
a en o
# en -0274,
e “e -05t4,
é es 0364,
2 ad -0184,
a ee o
Tetragonal Distortion or Jahn-Teller Distortion
‘The six coord competes in wich al the si ines between meta con and de ligan
are same and sid be reglroohedal complexes, A compen wil be lr cta whe he
leon amngemenin ande obs ssymneric (Le, tah ante, bisa loci
non depart) Ii baste o the fc tat metal range ecto wil ee al cr
ligands equal.
When either tag Of ez orbials are asymmenically flled Le, ciber fog oF eg orbials are
ciccwicaiy degenerate the regular octahedral geomet isnot he sable bt it roms ino a
distorted ocheirl geometry
“The ey orbitals paint directly towards the ligands therefore, when ¢ orbitals ae electronically
degenerate (Le, unsymmewially filed), some ligands are reeled more than the others. Therefore,
ther isa signifiant distortion in octahedral complexes. On he terhand, the 17 orbital iin between
theligads, therefor, the electronically degenerate fa, orbials cause avery small distortion.
In general, the distortion that cu comp nal distorion, A
teragonal istriön cecus when te two tans ligands onthe z-axis in anocahedral comple, sey M4,
removed iter towards the metal ion oF away fom the meta ion atom Motion of the rans- ligands
along the z-axis towards the metal cation produces a ergonal compression and motion ofthese ligands
aay from the meal cation produces 2 teragoral elongation. The shape of regular octabedral,
teragonaly compressed and ttagonaliy elongated compleses ar shown in Figure 49.
Ny
¿
Rz Ai |
N JN AN
i le
a a e
24949 Regi set sm (Tengen
The term tetragonal distorted is derived fom the fact hat when viewed along the z-axis, an
estadal comple looks like trago. The condon wich case such type of distortion vas
cried by the Jahn-Teller theorem, This theorem states that aby nonlinear molecule in an
‘letronically degenerate tates unsabl an e mos becomes distorte In such away sto
remove degeneracy, lower ts symmetry and lower tener.
Thetermelcetoncly degenerate stat refs othe ston a which an electrons can be granged
in me tan one orbits of equivalen energy. This station ases when the degenerate orbit are
usec filled, For example, in oenhedlly cortito Cu?“ io, e configuration is
iso degenerate because it has wo posite amegenens of locos fed, dl, oF
ED Em
CE
Electronica degenerate ae fre court
ith i iy on pose rangement tn ns ina leona
Bong, Te >, fr example, confusion noche symety x nondegnerte and
symmetic. Only one arrangement is possible for tree electrons because it is not possible to put wo
clectoas in one orbital which vilstes the Hund rule of maximum multiplicity.
Sate fa
Single arrangement ford? configuration
In arelrocthedrl ici he tale, d and ar degenerate. However fc
«clar uyameriall le cir. ordeal nine one elecon more han e
tes te pobre spit. th, riss an clon more han. 2 il
then the ligands approsching along z-axis will be repelled more than te ligends approaching along x-
and as is because ofthe fit hat on did à it gtc an hat of 2
(eb. Therefore, the ligands slong be ar ae themetal cation relative o these oa
and axes which move towards he tal ain, The easn france between metal ction andthe
Mens tobe shorter on x- and axes thatthe lig igand repulsion deceased as he igen move
away from the metal cation on z-axis, Therefore, distance between the metal cation and the ligands on
zaxis becomes larger and the distances between metal cation and ligands on x and y-axes become
store, ius, he complex undergoesatetragonal elongation Le, out distortion).
‘Size theligandson z-axis are a age dice or mt cation dan hat ofthe ligands on xandy
axes Therefore, be , abia will experience decease in repulsion (om the ligands and, therefore,
cry ofthe ds ori will decrease and hence ted rial is sablied. The d 7. obital wll
«pesen an inerase in repulsion fon the igus resulting an increase in energy ad hence the
da Wil therefor, be destabilized, wit the are reining costar. a similar way the
«Posies ofomialshaving componente, dy snd, lacs and tha of, vil increase and
tate dese e a obi eave Te, eel a at os
pie evo levels, an upper 2 à end e over, and culs is pli nto two levels, an
upper dy anda lower doubly degenerate dy add) The eraporal elongation is generally called the
‘etagonal disorion and is observed in most of temporal dented complexes, Crystal il sping
‘in tragonl elongation (ot) is shown in Figure 4.10
AP d y omit coins one elesron more tha the debi then he ligands apposching
long xan yates will be repelled mor than he gas sprshing slog the axis. tis because of
the it hat he eetron destin da à rl 5 eae thn that of 2 orbital, Tere, te
ligands log hex and rares are moved vay fom he ma cation lative 10 those on z-axis which
move towards the metal cation. Te eason fr be distance between metal cation andthe ligand to be
bare ons is that the lügen gan repulsion à decreed as ligas move away for the meal
con ons-ad panes, Therefore, he distance between the meta ction andthe ligands on and y-axes
‘ones lager and become shorter on 2 ans, Teer, the comples undergoes 2 tetragonal
compresion (Le 2-in distin)
ciccwicaiy degenerate the regular octahedral geomet isnot he sable bt it roms ino a
distorted ocheirl geometry
“The ey orbitals paint directly towards the ligands therefore, when ¢ orbitals ae electronically
degenerate (Le, unsymmewially filed), some ligands are reeled more than the others. Therefore,
ther isa signifiant distortion in octahedral complexes. On he terhand, the 17 orbital iin between
theligads, therefor, the electronically degenerate fa, orbials cause avery small distortion.
In general, the distortion that cu comp nal distorion, A
teragonal istriön cecus when te two tans ligands onthe z-axis in anocahedral comple, sey M4,
removed iter towards the metal ion oF away fom the meta ion atom Motion of the rans- ligands
along the z-axis towards the metal cation produces a ergonal compression and motion ofthese ligands
aay from the meal cation produces 2 teragoral elongation. The shape of regular octabedral,
teragonaly compressed and ttagonaliy elongated compleses ar shown in Figure 49.
Ny
¿
Rz Ai |
N JN AN
i le
a a e
24949 Regi set sm (Tengen
The term tetragonal distorted is derived fom the fact hat when viewed along the z-axis, an
estadal comple looks like trago. The condon wich case such type of distortion vas
cried by the Jahn-Teller theorem, This theorem states that aby nonlinear molecule in an
‘letronically degenerate tates unsabl an e mos becomes distorte In such away sto
remove degeneracy, lower ts symmetry and lower tener.
Thetermelcetoncly degenerate stat refs othe ston a which an electrons can be granged
in me tan one orbits of equivalen energy. This station ases when the degenerate orbit are
usec filled, For example, in oenhedlly cortito Cu?“ io, e configuration is
iso degenerate because it has wo posite amegenens of locos fed, dl, oF
ED Em
CE
Electronica degenerate ae fre court
ith i iy on pose rangement tn ns ina leona
Bong, Te >, fr example, confusion noche symety x nondegnerte and
symmetic. Only one arrangement is possible for tree electrons because it is not possible to put wo
clectoas in one orbital which vilstes the Hund rule of maximum multiplicity.
Sate fa
Single arrangement ford? configuration
In arelrocthedrl ici he tale, d and ar degenerate. However fc
«clar uyameriall le cir. ordeal nine one elecon more han e
tes te pobre spit. th, riss an clon more han. 2 il
then the ligands approsching along z-axis will be repelled more than te ligends approaching along x-
and as is because ofthe fit hat on did à it gtc an hat of 2
(eb. Therefore, the ligands slong be ar ae themetal cation relative o these oa
and axes which move towards he tal ain, The easn france between metal ction andthe
Mens tobe shorter on x- and axes thatthe lig igand repulsion deceased as he igen move
away from the metal cation on z-axis, Therefore, distance between the metal cation and the ligands on
zaxis becomes larger and the distances between metal cation and ligands on x and y-axes become
store, ius, he complex undergoesatetragonal elongation Le, out distortion).
‘Size theligandson z-axis are a age dice or mt cation dan hat ofthe ligands on xandy
axes Therefore, be , abia will experience decease in repulsion (om the ligands and, therefore,
cry ofthe ds ori will decrease and hence ted rial is sablied. The d 7. obital wll
«pesen an inerase in repulsion fon the igus resulting an increase in energy ad hence the
da Wil therefor, be destabilized, wit the are reining costar. a similar way the
«Posies ofomialshaving componente, dy snd, lacs and tha of, vil increase and
tate dese e a obi eave Te, eel a at os
pie evo levels, an upper 2 à end e over, and culs is pli nto two levels, an
upper dy anda lower doubly degenerate dy add) The eraporal elongation is generally called the
‘etagonal disorion and is observed in most of temporal dented complexes, Crystal il sping
‘in tragonl elongation (ot) is shown in Figure 4.10
AP d y omit coins one elesron more tha the debi then he ligands apposching
long xan yates will be repelled mor than he gas sprshing slog the axis. tis because of
the it hat he eetron destin da à rl 5 eae thn that of 2 orbital, Tere, te
ligands log hex and rares are moved vay fom he ma cation lative 10 those on z-axis which
move towards the metal cation. Te eason fr be distance between metal cation andthe ligand to be
bare ons is that the lügen gan repulsion à decreed as ligas move away for the meal
con ons-ad panes, Therefore, he distance between the meta ction andthe ligands on and y-axes
‘ones lager and become shorter on 2 ans, Teer, the comples undergoes 2 tetragonal
compresion (Le 2-in distin)
A ENACT,
‘ete or Metal Lin PS Coes PIE,
Em
ut 10 0) Degree lin e cai 0) Deets dil hin
Since the ligands on x and y-axes are atlonger ice from mea! cation thin hat ofthe ligands on
- suis, therefore, the d 2,2 oral will experience a deerese in rpuision from the ligands and,
therfore, energy ofd 2 orbital will dotease. The 3 orbital will experience an increase in eplsion
om re ligands resulting in an increase in energy, with he barycentre remaining constant, Ina similar
[vay the energies ofthe octal havingx-and-companea (dy abil) will decrease and hat of having
=-component (ie. d and da.) will inreas, The crystal fi spliing in tetragonal compression (or
in) complexes is shown in Figure 4.11
‘Since in teragoal compresion fur and on and y-axes reel the high density of electrons in
3,7 orbital whereas in agonal elongation only two ligands on ans reel he hgh density of
electons in d,s orbital Therefore ther s moe repulsion in tagonal compression than at of
tetragonal elongation. Therefor, tagona lorgaion is mor stable than tetragonal compren
‘Thus, tetragonal elongation is known to bea tetragonal distortion,
‘The sinn Jae stone are general oberen igh pi (2, e) low in
E, eat? (6, e cuasi ocd geome besas in these confus
e bals are electronically degenerate and post towards the igands deny. Some examples of
chmpounds which undergo song la-Teller disrion in octahodra feld are CF> and May,
(E.G, ef), NANO; (Lonspin, de, some copper (I) compounds such as Cu, Ch,
Cubes CuCla- 480, (d?, 14.6) In all these compounds the metal cations are octakedaly
surrounded by th ligands at ota re until filed, therefore, thee ae two longer
onde on z-axis and fou sore bonds on x- and yes.
The Jahn-Telle theorem doesnot pedir wich typeof disorion wil take place.
ANi (11) complex surrounded by four strong and two weak ligands undergoes tetragonal distortion
but not due to Jaho-Telle distarion because ey oils (4.2 „2 and d 2) ee not electronics
degenerate. The varying elecran tepulsions betwee WHE non-equivalent ligands and the de electrons of
‘heme cation split orbite geatenentand 9 to smal extent as shown in Figure 4.2.
Inthis case ie magnitud of exceeds the pig energy (P) all the ix igands ro Wea, hen Ni
D form eps cth del comple. On haber hand, fal the igands ar song en Ni) ma
square planar complex.
des S
i
dap de
we UE
à
Dors
Sethe
QC] KU}
Figure 42, Sleeve rangement o (a) Weak ctra el and x;
Ben MEN eu ee
‘The octahedral complexes in wich fg orbitals are electoncally degenerate (Le, asymmetrically
filled also undergo Jahn-Teller distortions but the distonions are very weak tobe observed because the
tag orbitals donot point direct atthe ligands and relaively less affected by the ligands The 4%, low
‘ete or Metal Lin PS Coes PIE,
Em
ut 10 0) Degree lin e cai 0) Deets dil hin
Since the ligands on x and y-axes are atlonger ice from mea! cation thin hat ofthe ligands on
- suis, therefore, the d 2,2 oral will experience a deerese in rpuision from the ligands and,
therfore, energy ofd 2 orbital will dotease. The 3 orbital will experience an increase in eplsion
om re ligands resulting in an increase in energy, with he barycentre remaining constant, Ina similar
[vay the energies ofthe octal havingx-and-companea (dy abil) will decrease and hat of having
=-component (ie. d and da.) will inreas, The crystal fi spliing in tetragonal compression (or
in) complexes is shown in Figure 4.11
‘Since in teragoal compresion fur and on and y-axes reel the high density of electrons in
3,7 orbital whereas in agonal elongation only two ligands on ans reel he hgh density of
electons in d,s orbital Therefore ther s moe repulsion in tagonal compression than at of
tetragonal elongation. Therefor, tagona lorgaion is mor stable than tetragonal compren
‘Thus, tetragonal elongation is known to bea tetragonal distortion,
‘The sinn Jae stone are general oberen igh pi (2, e) low in
E, eat? (6, e cuasi ocd geome besas in these confus
e bals are electronically degenerate and post towards the igands deny. Some examples of
chmpounds which undergo song la-Teller disrion in octahodra feld are CF> and May,
(E.G, ef), NANO; (Lonspin, de, some copper (I) compounds such as Cu, Ch,
Cubes CuCla- 480, (d?, 14.6) In all these compounds the metal cations are octakedaly
surrounded by th ligands at ota re until filed, therefore, thee ae two longer
onde on z-axis and fou sore bonds on x- and yes.
The Jahn-Telle theorem doesnot pedir wich typeof disorion wil take place.
ANi (11) complex surrounded by four strong and two weak ligands undergoes tetragonal distortion
but not due to Jaho-Telle distarion because ey oils (4.2 „2 and d 2) ee not electronics
degenerate. The varying elecran tepulsions betwee WHE non-equivalent ligands and the de electrons of
‘heme cation split orbite geatenentand 9 to smal extent as shown in Figure 4.2.
Inthis case ie magnitud of exceeds the pig energy (P) all the ix igands ro Wea, hen Ni
D form eps cth del comple. On haber hand, fal the igands ar song en Ni) ma
square planar complex.
des S
i
dap de
we UE
à
Dors
Sethe
QC] KU}
Figure 42, Sleeve rangement o (a) Weak ctra el and x;
Ben MEN eu ee
‘The octahedral complexes in wich fg orbitals are electoncally degenerate (Le, asymmetrically
filled also undergo Jahn-Teller distortions but the distonions are very weak tobe observed because the
tag orbitals donot point direct atthe ligands and relaively less affected by the ligands The 4%, low
spin d* and 45, high spin d® and d” octahedral complexes undergo slight or weak Jaha-Teller
dstonions. The octahedral complex of d! configuration shows zán distortion, In this case peut
Astron does not remove the degeneracy, ice even afer distortion there are sil 0 dy and dar
orbital which ae available fr he electron to occupy.
‘The octahedral complex o? configuran shows ;ut distortion. The two orbitals dy and dye
having one electron each remove the degeneracy since both these two orbitels have component and
repel the ligands more strongly on -axis than he ipands on x and y-axes,
For the same reason, relatively weak distortions are expected in tetrahedrl complexes with
a, 21,4? anda? configurations. Inthe d? anda? tetrahedral complexes one ofthe f orbitals bas one
electron more than the thers which causes an elongation in he tetrahedron, Onthe other bend, ind and
a? tetrahedral complexes, one of the three f orbitals has one electron les then the others. This situation
causes a fattening ofthe tetahedral complex.
Static and Dynamic Jahn-Teller Distortions,
Some complexes show tragen distin under ll conditions Le, insoié as wel sin soon,
citer tower oreatively higher temperatures This tortion called te static Jak Tell distortion
Tnthesecomplesesthespilting oz, n/a, otal quite highs that he bea energy valle
willnotbe uen tales population foal in distorted geometry. This ype of abner
fags a ‘wen ez oss ae eectonially degenerate. Hene, this disoia is song and
em —
There are some exceptions 10 the Jahneler distortion in which certain physical properties
soretpon to syrmetri sete when distortions ar expected. thee complexes no dston can
be detected a room temperature because the direcion of distri (say an elongation of one as an
osahedron) randomly moves among the able syranety axes ofthe complexes mor rai than
she physical metsuement.inthesecomplencs real energy availabe a rom tempera cases
10 equalize the population of te comple in in the totragonal elongated and teagosal compressed
comes. This called yuamic Jao- Tele disarin. Ts, he physical measurement dees en
Average situe with 0 or wea drin. The dsorion can be detected at rezing temperate
because cooling of th compound wil show the asiations enough resulting ina singe ét)
sercture, Dynamic Jahn Tell: disyion ox i complexes in which spliting of fgg and! or
ova male eee
For example: +
~The complex [Ti (H30)6]°* and{Fe(H,0)¢}** show dynamic Jahn-Teller distortion and appear
cher. In these complexes bo the types of got (Le, tetragonal elongation ‘al egal
-compresion)exstin equilibrium. nthe: competes the distortions mal sncethe degeneracy ces
ag ofits, a
std .
oe. AI Pye
qu
‘Square Planar Complexes
In an ot comple oF (with weak igen, the elecone configuration of Ni (D is
1 ke, tg Andale gmmetcally lé, he electron density ind cl lng axis
isgreterdanthatof 2; otal long thex-andy-axes because d 2 orbitals the liner combination
ofd 2,2 and 7_ à tal. The electon density in d 2 orbita wil reel he ligands on zis more
strongly whereas telecom density ind. orbital will rep the fgands on wand axes o lesser
extent, Therefore, Ihe distance between metal cation and ligand on zasis is age han that on and
ras. Ts, ergy of dp cba becomes lower relative tothe d 2 Le. there is pli 1 e
‘orbitals. But incase of weak ld complexes like [Ni(H¿0)6]% and [Ni(NH,)g]* the spliting i
smal because charge on metal aio is ot high andthe ligands are aso not too strong. Therefore, these
complexes are cosidrdtobegulacoctaodrl andthe energy ofd 2 and, wilbesameie eg
bil are degenerate. But ifiheignds ae sufciently strong, the difference in energy between these
to orbitals becomes larger andthe unpaired electron inthe d > 2 erbital ean dropdown and psirwith
the ecron lady inthed a oa. Now hed, orbita becomes empty. There, son sands
can approach the metal cation along a and y-axes without any difficulty ste d 2 exit is empty.
“The ligands approaching he metal cation along axis experience very strong cepustons fom he filed
4 orbital. Thus, only feu ligan can form bonds with the metal catión
‘The amount of tetragonal elongation ad thespiting of d-orbitals depends upon the rat of metal
ation and he ligand The metal cations wih configuration frm square planas complex wit tong
tigands such as CN Nit} for square planar complex{Ni(CN), wiésrongCN” gado. Since
(D crystal fed spliting fr dd and Sd series transition metals and for highly charged metals very
large, i ligands repulsion are minimized duet age size ofthe metals. Therefore al the complexes
of Pa (1D), Pe GH), Au (UD are square pana inespectve ofthe nature ofthe ligands ie, whether the
ligands are weak or strong. The ysl fil pliting in square planar complexes shown in Figure 4.10
In squat planar complexes of Co (1), Ni (I) and Cul} the energy of obial neatly same as
je and dz orbitals whereas in square planar complex of Pa (1D), Pr (abd Au (1D, energy of d 2
“orbital is iower than that of and da abia
CETTE ES
‘The spectroscopie sul ave
her la} Ge.ap>ao
‘Consequences of Jahn-Teller Distortion
(1) Stability of Cu” Complexes:
Fore give gad the lative suit o omplxes with dpesive metal fous of ist ation
series. follow the onder Be? < Sr?" < Ca?" < Mg?" <Mn?ee? <a? < Ni < Cu
> Zn?*, This series is cal the Irving William series, The extra stability of Cu) complexes is
dstonions. The octahedral complex of d! configuration shows zán distortion, In this case peut
Astron does not remove the degeneracy, ice even afer distortion there are sil 0 dy and dar
orbital which ae available fr he electron to occupy.
‘The octahedral complex o? configuran shows ;ut distortion. The two orbitals dy and dye
having one electron each remove the degeneracy since both these two orbitels have component and
repel the ligands more strongly on -axis than he ipands on x and y-axes,
For the same reason, relatively weak distortions are expected in tetrahedrl complexes with
a, 21,4? anda? configurations. Inthe d? anda? tetrahedral complexes one ofthe f orbitals bas one
electron more than the thers which causes an elongation in he tetrahedron, Onthe other bend, ind and
a? tetrahedral complexes, one of the three f orbitals has one electron les then the others. This situation
causes a fattening ofthe tetahedral complex.
Static and Dynamic Jahn-Teller Distortions,
Some complexes show tragen distin under ll conditions Le, insoié as wel sin soon,
citer tower oreatively higher temperatures This tortion called te static Jak Tell distortion
Tnthesecomplesesthespilting oz, n/a, otal quite highs that he bea energy valle
willnotbe uen tales population foal in distorted geometry. This ype of abner
fags a ‘wen ez oss ae eectonially degenerate. Hene, this disoia is song and
em —
There are some exceptions 10 the Jahneler distortion in which certain physical properties
soretpon to syrmetri sete when distortions ar expected. thee complexes no dston can
be detected a room temperature because the direcion of distri (say an elongation of one as an
osahedron) randomly moves among the able syranety axes ofthe complexes mor rai than
she physical metsuement.inthesecomplencs real energy availabe a rom tempera cases
10 equalize the population of te comple in in the totragonal elongated and teagosal compressed
comes. This called yuamic Jao- Tele disarin. Ts, he physical measurement dees en
Average situe with 0 or wea drin. The dsorion can be detected at rezing temperate
because cooling of th compound wil show the asiations enough resulting ina singe ét)
sercture, Dynamic Jahn Tell: disyion ox i complexes in which spliting of fgg and! or
ova male eee
For example: +
~The complex [Ti (H30)6]°* and{Fe(H,0)¢}** show dynamic Jahn-Teller distortion and appear
cher. In these complexes bo the types of got (Le, tetragonal elongation ‘al egal
-compresion)exstin equilibrium. nthe: competes the distortions mal sncethe degeneracy ces
ag ofits, a
std .
oe. AI Pye
qu
‘Square Planar Complexes
In an ot comple oF (with weak igen, the elecone configuration of Ni (D is
1 ke, tg Andale gmmetcally lé, he electron density ind cl lng axis
isgreterdanthatof 2; otal long thex-andy-axes because d 2 orbitals the liner combination
ofd 2,2 and 7_ à tal. The electon density in d 2 orbita wil reel he ligands on zis more
strongly whereas telecom density ind. orbital will rep the fgands on wand axes o lesser
extent, Therefore, Ihe distance between metal cation and ligand on zasis is age han that on and
ras. Ts, ergy of dp cba becomes lower relative tothe d 2 Le. there is pli 1 e
‘orbitals. But incase of weak ld complexes like [Ni(H¿0)6]% and [Ni(NH,)g]* the spliting i
smal because charge on metal aio is ot high andthe ligands are aso not too strong. Therefore, these
complexes are cosidrdtobegulacoctaodrl andthe energy ofd 2 and, wilbesameie eg
bil are degenerate. But ifiheignds ae sufciently strong, the difference in energy between these
to orbitals becomes larger andthe unpaired electron inthe d > 2 erbital ean dropdown and psirwith
the ecron lady inthed a oa. Now hed, orbita becomes empty. There, son sands
can approach the metal cation along a and y-axes without any difficulty ste d 2 exit is empty.
“The ligands approaching he metal cation along axis experience very strong cepustons fom he filed
4 orbital. Thus, only feu ligan can form bonds with the metal catión
‘The amount of tetragonal elongation ad thespiting of d-orbitals depends upon the rat of metal
ation and he ligand The metal cations wih configuration frm square planas complex wit tong
tigands such as CN Nit} for square planar complex{Ni(CN), wiésrongCN” gado. Since
(D crystal fed spliting fr dd and Sd series transition metals and for highly charged metals very
large, i ligands repulsion are minimized duet age size ofthe metals. Therefore al the complexes
of Pa (1D), Pe GH), Au (UD are square pana inespectve ofthe nature ofthe ligands ie, whether the
ligands are weak or strong. The ysl fil pliting in square planar complexes shown in Figure 4.10
In squat planar complexes of Co (1), Ni (I) and Cul} the energy of obial neatly same as
je and dz orbitals whereas in square planar complex of Pa (1D), Pr (abd Au (1D, energy of d 2
“orbital is iower than that of and da abia
CETTE ES
‘The spectroscopie sul ave
her la} Ge.ap>ao
‘Consequences of Jahn-Teller Distortion
(1) Stability of Cu” Complexes:
Fore give gad the lative suit o omplxes with dpesive metal fous of ist ation
series. follow the onder Be? < Sr?" < Ca?" < Mg?" <Mn?ee? <a? < Ni < Cu
> Zn?*, This series is cal the Irving William series, The extra stability of Cu) complexes is
due 10 Jahn Felle dstrtion, During the distortion to eecmons ase loweredin cory while only
one is rised an equal amount of energy,
@) The complex (Cu(em)a]%* is unstable because Jahn-Tller distortion cians strain into
‘tylenediamine molecule atached along z-axis Figure 4.13)
LIN
Ll x
stan te compe
logre,
Ja te simil manner rans- {Cu (en) (130) 2" ie mor stabi the Ou) (5202)
because Jahn-Teller distoion causes stain in stylandinine moleae alos zaxis in
e-{Caleada(H20)2* (Figure 4.14).
f oy da
| | OD
, laos Ly
FO me
bok | 44
‘Say Pe
o . Eure 4,
(GY Sn the taire Kurs, the two CaF distances on axis ae 196 A and the remaining four
(Gu--F distances in x plane are at 2.07 A. It is due to Jan Tele compression
(9 Complexes of Au (U) ion are unstable and undergo disroparonaon 10 Au (D and Au (HI)
| Wheres the compiex of Cu (1) and Ag (1) are comparivey more stable (ten be expected o be
the same stability of Au (CU) and Ag (1) complees sine all ave 4° configuration and
| ‘undergo Jabn-Teller distortion, Since À value ‘increases où moving down the group, therefore, 4
value for Au (I) complexes is maximum among the tree. The high value of A causes a high
sain ofthe last elton ia the d à eal Terre, A (i) becomes extremely
‘active and can undergo ether oxidation to Au (IN), ad sytem ac reduction to Au (1), a €"
‘pst. The Au QU forms square plas complex becas Au (os linear comple. ~
5) The spitting of absorption bands inthe electronic spectra of complex due to Jahn-Teller distortion.
‘Applications of CFSE
(Q) Enthapy of Hydration of Transition Metal Tons: En a aqueous solution, te meta cations
ae surounded by polar water molecules. This proces is called as hydration, Thee are six water
molecules in he primary hydration sphere around the metal cation form an ot aque complex.
Héron energy isthe energy released when gaseous meal cations get hyd.
ME +60 —> [M (M0) ]"* +hydraion energy
Hydıation energy ofa metal ation increases wit increase ineffective nuclear charge and decrease
in one radi because these (wi FAIR Dr THE water molecaes close tothe metal cation, MU?
resulting inte increased electrostatic attraction betwee the mea cation and de water molecules, For
<iposive tion metal ation of 3d series, the effective clear charg increases and onic radi
decrease across a period. We expe the electrostatic action between metal ction and the water
‘molecules increase regularly along the transition meta series. Therefore, the hytation energy should
increase regal from Ca to Zu?" sad à straight Line shoul be obtained as shown by dotted line in
Figure 415. In fact here are some deviations from a linear relationship. When iposive or positive
sal cation of34-sres transition metal ges hydrated, high pin octahedra aqua comple is formed.
‘Therefore, not only the hydration energy but CFSE is aso evolved, Thus, the experimental hydration,
energy isthe sum of theoretical ydration energy and CFSE.
Experimental yatio energy = Theoretical or expected iyéraion energy + CFSE
20
2700
2500
2300
2100.
ce sett Ti CP Mn Be Co NP Où Za?
eo 2 3 4 5 6 7 8 9 vw
‘gues,
one is rised an equal amount of energy,
@) The complex (Cu(em)a]%* is unstable because Jahn-Tller distortion cians strain into
‘tylenediamine molecule atached along z-axis Figure 4.13)
LIN
Ll x
stan te compe
logre,
Ja te simil manner rans- {Cu (en) (130) 2" ie mor stabi the Ou) (5202)
because Jahn-Teller distoion causes stain in stylandinine moleae alos zaxis in
e-{Caleada(H20)2* (Figure 4.14).
f oy da
| | OD
, laos Ly
FO me
bok | 44
‘Say Pe
o . Eure 4,
(GY Sn the taire Kurs, the two CaF distances on axis ae 196 A and the remaining four
(Gu--F distances in x plane are at 2.07 A. It is due to Jan Tele compression
(9 Complexes of Au (U) ion are unstable and undergo disroparonaon 10 Au (D and Au (HI)
| Wheres the compiex of Cu (1) and Ag (1) are comparivey more stable (ten be expected o be
the same stability of Au (CU) and Ag (1) complees sine all ave 4° configuration and
| ‘undergo Jabn-Teller distortion, Since À value ‘increases où moving down the group, therefore, 4
value for Au (I) complexes is maximum among the tree. The high value of A causes a high
sain ofthe last elton ia the d à eal Terre, A (i) becomes extremely
‘active and can undergo ether oxidation to Au (IN), ad sytem ac reduction to Au (1), a €"
‘pst. The Au QU forms square plas complex becas Au (os linear comple. ~
5) The spitting of absorption bands inthe electronic spectra of complex due to Jahn-Teller distortion.
‘Applications of CFSE
(Q) Enthapy of Hydration of Transition Metal Tons: En a aqueous solution, te meta cations
ae surounded by polar water molecules. This proces is called as hydration, Thee are six water
molecules in he primary hydration sphere around the metal cation form an ot aque complex.
Héron energy isthe energy released when gaseous meal cations get hyd.
ME +60 —> [M (M0) ]"* +hydraion energy
Hydıation energy ofa metal ation increases wit increase ineffective nuclear charge and decrease
in one radi because these (wi FAIR Dr THE water molecaes close tothe metal cation, MU?
resulting inte increased electrostatic attraction betwee the mea cation and de water molecules, For
<iposive tion metal ation of 3d series, the effective clear charg increases and onic radi
decrease across a period. We expe the electrostatic action between metal ction and the water
‘molecules increase regularly along the transition meta series. Therefore, the hytation energy should
increase regal from Ca to Zu?" sad à straight Line shoul be obtained as shown by dotted line in
Figure 415. In fact here are some deviations from a linear relationship. When iposive or positive
sal cation of34-sres transition metal ges hydrated, high pin octahedra aqua comple is formed.
‘Therefore, not only the hydration energy but CFSE is aso evolved, Thus, the experimental hydration,
energy isthe sum of theoretical ydration energy and CFSE.
Experimental yatio energy = Theoretical or expected iyéraion energy + CFSE
20
2700
2500
2300
2100.
ce sett Ti CP Mn Be Co NP Où Za?
eo 2 3 4 5 6 7 8 9 vw
‘gues,
EA
1 hydration energies fr dipstive melon: ofthe 3d transition elemen are
potasa fretion of atomic number, a double humped cuve haine (Figure 4.13). The two bumps
Insuch a curve ae due to addition or contribution of CFSE tothe expected hydration energy
Since the CFSE of Ca (1, Ma (I) and Zo (D ions in hgh pin octahedral comple is zero
‘Therefore, th hydration energies of thse ios leon the sip lin and does not deviate ram the
experimental value. Far a particular mea ation itis poso calculate he net contribution af CFSE
(o hein enhalpy.
(0) Lattice Energy’: Latce energy isthe change in energy when one mole of an fonie ral is
formed rm its constituent gaseous ions
MX) MK (+ Late energy
rom the Born Lande equation
MAT qi
a ®
Lattice energy (U) =
Le Lattice «2
D
Where N = Avogadro number, A = Madelung constant which depends upon the geometry of the
crystal, Z* and 2 are Ihe charges on cation and anion respectively, y =interionic distance, n = Bors
exponent
“According to Bor Land's equation, the ace enemy oan ni tal increases with increase
product of Z* and Z~ and decreases aterionic distance (ry). The lattice energy for halides of
dipositive metal ions of the 3d- transition elements should increase fromCa” to Zn?* ion anda straight
fine should be observed arstrowa by doned line in Figure 4.16. In fact there are some deviations from a
tinea telaonshi, Some wansition real compounds have higher measured lace energy (obtained by
lens using Born Haber cycle than tat of expected (date by Bom Landes equation. In
contras experimental and theoretical tio energies or main grow ar in close spreement because
these compounds do not have CESE.
Inthe ionic crystal of halides ofdipositve or passe meta ion of 4. series transition elements, |
the metal cations occupy octahedral voids. Therefore, the coordintion numberof the metal cation six
‘The anangement of ales around the metal cation i analogous ote high spin octahedral complexes.
‘Therefore, the CFSE contributes to the experimental lace energy. Ts, the contribution of CPSE.
aus the higher experimental lattice energy than the expected Since CPSE values for different meta
‘cations are different, therefor, experimental latice energy increases replay from CaX 10 Zu. 1
the experimental stice energies for CaCl to ZaCtz areploted asa funciono? atomic number,» double
Inumped curve is obtain (Figure 4.16).
Since CFSE for Ca?* (4°), high spin Mn?" (a and Za octahodra field is zero. Thus, ions
Ca¥, Mn? and Zn?* tie onthe straight ine.
For a weak field octahedral field, V2" (4°) and Ni?" (48) have the greatest CPSE (- 1.2 40).
‘Therefor, these two ons show two maxima onthe curve above the sight ine.
- “spinor high spin ostahodral field might be expected to decrease regularly from Ca?" to Zu?" because
ARA =
3200
a
Lattice energy (in KF mot")
5
q
20!
an Ly} tt
oe! a Tv Où M Re ca M OP aah
foo 12 3 4 s 6 7 8 9 «
Starts
The comet vale of lice entry can be clei
Laie ene.
Sina pos are obtained forthe late ens o ther AT and MAY gata
(mi ai of Divalent Metal ans o Series Trans Elements:
‘he ioc adi of pote and ose mtl catas ofS cis transition tas nthe tw
by abstracting the CFSE from experimental
‘heinceasing elective nuclear charge an poo sil ef of d- electrons cause te increase of
face of aration between metal ction andthe ian and ligas may approach the meal tin
mor sl. But some ons show diserpanies om ls regul end of decreasing ionic ai
Toe ini di of C2?*, Mn and Zo" fons in a ak the ld decrease smoothly with
increasing nuclear charge because these ions are sereened by aspherical charge distribution. The, e?
soda? ios have smaller rad iria weak or song Gel thn expected because electron occupy fp
cobs wich ei the region between te igands. The aus of hse ons are less bilan they
Had a spherical distribution of eestor, However, troie rai in ctahedra! il deseases roma!
tod ions a he muclar charges increases In wea Feld ocurra complexes of 4* and ions
clone re aed successively othe ey oil, Tit ern cases an increase ofthe relative
talus of oa compared o that of tonus, ral ae pin dre at the ligands. This
1 hydration energies fr dipstive melon: ofthe 3d transition elemen are
potasa fretion of atomic number, a double humped cuve haine (Figure 4.13). The two bumps
Insuch a curve ae due to addition or contribution of CFSE tothe expected hydration energy
Since the CFSE of Ca (1, Ma (I) and Zo (D ions in hgh pin octahedral comple is zero
‘Therefore, th hydration energies of thse ios leon the sip lin and does not deviate ram the
experimental value. Far a particular mea ation itis poso calculate he net contribution af CFSE
(o hein enhalpy.
(0) Lattice Energy’: Latce energy isthe change in energy when one mole of an fonie ral is
formed rm its constituent gaseous ions
MX) MK (+ Late energy
rom the Born Lande equation
MAT qi
a ®
Lattice energy (U) =
Le Lattice «2
D
Where N = Avogadro number, A = Madelung constant which depends upon the geometry of the
crystal, Z* and 2 are Ihe charges on cation and anion respectively, y =interionic distance, n = Bors
exponent
“According to Bor Land's equation, the ace enemy oan ni tal increases with increase
product of Z* and Z~ and decreases aterionic distance (ry). The lattice energy for halides of
dipositive metal ions of the 3d- transition elements should increase fromCa” to Zn?* ion anda straight
fine should be observed arstrowa by doned line in Figure 4.16. In fact there are some deviations from a
tinea telaonshi, Some wansition real compounds have higher measured lace energy (obtained by
lens using Born Haber cycle than tat of expected (date by Bom Landes equation. In
contras experimental and theoretical tio energies or main grow ar in close spreement because
these compounds do not have CESE.
Inthe ionic crystal of halides ofdipositve or passe meta ion of 4. series transition elements, |
the metal cations occupy octahedral voids. Therefore, the coordintion numberof the metal cation six
‘The anangement of ales around the metal cation i analogous ote high spin octahedral complexes.
‘Therefore, the CFSE contributes to the experimental lace energy. Ts, the contribution of CPSE.
aus the higher experimental lattice energy than the expected Since CPSE values for different meta
‘cations are different, therefor, experimental latice energy increases replay from CaX 10 Zu. 1
the experimental stice energies for CaCl to ZaCtz areploted asa funciono? atomic number,» double
Inumped curve is obtain (Figure 4.16).
Since CFSE for Ca?* (4°), high spin Mn?" (a and Za octahodra field is zero. Thus, ions
Ca¥, Mn? and Zn?* tie onthe straight ine.
For a weak field octahedral field, V2" (4°) and Ni?" (48) have the greatest CPSE (- 1.2 40).
‘Therefor, these two ons show two maxima onthe curve above the sight ine.
- “spinor high spin ostahodral field might be expected to decrease regularly from Ca?" to Zu?" because
ARA =
3200
a
Lattice energy (in KF mot")
5
q
20!
an Ly} tt
oe! a Tv Où M Re ca M OP aah
foo 12 3 4 s 6 7 8 9 «
Starts
The comet vale of lice entry can be clei
Laie ene.
Sina pos are obtained forthe late ens o ther AT and MAY gata
(mi ai of Divalent Metal ans o Series Trans Elements:
‘he ioc adi of pote and ose mtl catas ofS cis transition tas nthe tw
by abstracting the CFSE from experimental
‘heinceasing elective nuclear charge an poo sil ef of d- electrons cause te increase of
face of aration between metal ction andthe ian and ligas may approach the meal tin
mor sl. But some ons show diserpanies om ls regul end of decreasing ionic ai
Toe ini di of C2?*, Mn and Zo" fons in a ak the ld decrease smoothly with
increasing nuclear charge because these ions are sereened by aspherical charge distribution. The, e?
soda? ios have smaller rad iria weak or song Gel thn expected because electron occupy fp
cobs wich ei the region between te igands. The aus of hse ons are less bilan they
Had a spherical distribution of eestor, However, troie rai in ctahedra! il deseases roma!
tod ions a he muclar charges increases In wea Feld ocurra complexes of 4* and ions
clone re aed successively othe ey oil, Tit ern cases an increase ofthe relative
talus of oa compared o that of tonus, ral ae pin dre at the ligands. This
AAA
causes to a repulsion of ligands and an increase inthe jon adius of metal ion in octadral field. Ina.
weak field octal complex ofa ion, de lastelectron enter int the e orbitals which causes more
‘epuision ofthe ligands and further increase in ionic radius of meta ion in octahedral field The leon
density round the metal cation is spherically symmetric, therefore, this fon lies onthe smoot line. I
‘oni radius is smaller than hat of system but large than that of d weal field system. The addition
of electrons beyond the d* in a weak field octahedral complexes leads to a repeton ofthe same
sequence, except that the d- orbitals now become doubly filed The variation of ionic radi of dpestve
metal ions of transition element in wea field complexes as a function of atom number is shown in
Figure 417.
ue
100
9
„4
o
Joni rai Gn pm)
m +
ST Mr Bet Cot Nie Ct ze
“oa 345 6 7 # 9 «
Furet.
For ol diportive and pose ons af 34 sis tas elements, the Tai rain strong
Octabadal Geld decrees ul te, cng is ached. The fy base ci
Bos ind providing or ing of acia care. The increased ea cage
causes the increase oc fan been mei ud and ands neat ad? ed
4! metations in strong field the sectors ae wcesively added 0 orbitals. The ist clectronaded
1044 orbital cause an increas in ele oi radins of on compared to tht of iomin strong eld
because oils pimin ica be igen cess repuso gens ti similar wy nio
Caine fom d ta mel sun fe. Tb ein of oie ad pas men
Fons of 3 sc tension clement is shown in weak ad tong fil opens ta ion ef ome
‘number is shown in Figure 4.18. 5 7
so
E
E)
En
É
6
s
E ie
sot ce Mat Fe col Nt Qt zat Gat
foo 1 2 3 4 5 6 7 8-9 w
Horse
cam
(4) Structures of Spinels : Spicls ae ie mixed metal oxide having the formula À B O4 or
oy
40,8) 05, Wher A can bea group 2 aora asien mei in 2 oxidation san cmt a
group 13 metal o transition metal in +3 oxkation state, The oxide anions form a cubi clase packed
(ep) or face centred cubic (e) latte with fou cade! voids and eight tetrahedral voids per ABO
nit. One third of the mea ions occupy trahera voids ad two tied occupy the atada! void
Tetrabedl voids are the daube ofthe octahedtal voids and octahedral voids are equal othe Ltice
points Therefore, ==
‘Number ofterabcdral voids = x Number of octahedrl voids
Number of octabedr voids = Number of tc ponts
‘Therefore, Number of traca voids » 2 x Number of octahedral voids.
=2 Number of iatice points.
Spinel ae classified into two eatepaies
(4) Normal spines (6) Inverse spines
(a) Normal Spinels: [na normal spinc, A jons occupy one cight ofthe teal ods nd pe
fons occupy half of the octahedral vids, Thus, normal spinels can be written as A KB) JOa
Examples of nonnal spinels are MgAlz0s, MeCr204, NiCr204,MnjO4, 00304 eto
(@)IaverseSpinels Inan iver spinel if BP" ons have exchanged place wal he
A?* ons, nother words, the A ions ocepy thai octaedral void slong wth afte D ions
A RA Y
causes to a repulsion of ligands and an increase inthe jon adius of metal ion in octadral field. Ina.
weak field octal complex ofa ion, de lastelectron enter int the e orbitals which causes more
‘epuision ofthe ligands and further increase in ionic radius of meta ion in octahedral field The leon
density round the metal cation is spherically symmetric, therefore, this fon lies onthe smoot line. I
‘oni radius is smaller than hat of system but large than that of d weal field system. The addition
of electrons beyond the d* in a weak field octahedral complexes leads to a repeton ofthe same
sequence, except that the d- orbitals now become doubly filed The variation of ionic radi of dpestve
metal ions of transition element in wea field complexes as a function of atom number is shown in
Figure 417.
ue
100
9
„4
o
Joni rai Gn pm)
m +
ST Mr Bet Cot Nie Ct ze
“oa 345 6 7 # 9 «
Furet.
For ol diportive and pose ons af 34 sis tas elements, the Tai rain strong
Octabadal Geld decrees ul te, cng is ached. The fy base ci
Bos ind providing or ing of acia care. The increased ea cage
causes the increase oc fan been mei ud and ands neat ad? ed
4! metations in strong field the sectors ae wcesively added 0 orbitals. The ist clectronaded
1044 orbital cause an increas in ele oi radins of on compared to tht of iomin strong eld
because oils pimin ica be igen cess repuso gens ti similar wy nio
Caine fom d ta mel sun fe. Tb ein of oie ad pas men
Fons of 3 sc tension clement is shown in weak ad tong fil opens ta ion ef ome
‘number is shown in Figure 4.18. 5 7
so
E
E)
En
É
6
s
E ie
sot ce Mat Fe col Nt Qt zat Gat
foo 1 2 3 4 5 6 7 8-9 w
Horse
cam
(4) Structures of Spinels : Spicls ae ie mixed metal oxide having the formula À B O4 or
oy
40,8) 05, Wher A can bea group 2 aora asien mei in 2 oxidation san cmt a
group 13 metal o transition metal in +3 oxkation state, The oxide anions form a cubi clase packed
(ep) or face centred cubic (e) latte with fou cade! voids and eight tetrahedral voids per ABO
nit. One third of the mea ions occupy trahera voids ad two tied occupy the atada! void
Tetrabedl voids are the daube ofthe octahedtal voids and octahedral voids are equal othe Ltice
points Therefore, ==
‘Number ofterabcdral voids = x Number of octahedrl voids
Number of octabedr voids = Number of tc ponts
‘Therefore, Number of traca voids » 2 x Number of octahedral voids.
=2 Number of iatice points.
Spinel ae classified into two eatepaies
(4) Normal spines (6) Inverse spines
(a) Normal Spinels: [na normal spinc, A jons occupy one cight ofthe teal ods nd pe
fons occupy half of the octahedral vids, Thus, normal spinels can be written as A KB) JOa
Examples of nonnal spinels are MgAlz0s, MeCr204, NiCr204,MnjO4, 00304 eto
(@)IaverseSpinels Inan iver spinel if BP" ons have exchanged place wal he
A?* ons, nother words, the A ions ocepy thai octaedral void slong wth afte D ions
A RA Y
>" ions occupy A 1 of the tetrahedral voids. Inverse spinels can be
whereas the other hal of à
un wen
representadas! B LA BO.
Example of inverse spinels re CrFe 04, e304, Nife04, Mpeg, NALO ee
In general, th spines having Fe ons are iver spinels
Predicting the Structure of Spinels
‘An important factor in detemining whether a spinel is normal or averses the CESE ofthe cations
‘occupying the erahedral and octabedral voids. The metal ction in tetrahedral and octet voids are
surrounded by four and six oxide ons respectively. Thus, Ue metleations occupying the erhedeal
and octahedra voids are considered to form tetrahedral and octahedsal complexes respectively. The
‘oxide ion bebaves asa weak ligand. To determine whether a spine i normal or inves, we ave to
compare the CESE in octahedral and tetakedral environment for both A2 and ions. IF CFSE for
13°" ion in octahedral vids ws preter than that of Bin tetrahedral and A in bth he tetrabodal and
octahedrl voids, the spinel wil be normal.
AT CESE for A ion in octahedra void is greater than A2* in tttaedral and BP" in both the
tetrchedral and octahedral void, ten the spine wil be inverse
Examples
wm
330,0,
(0 behaves as a weak ligand.
„Set Tetcabedral
Mo?) ef en
CFSE =[-04x3+06x2)A, CFSE=[-027x2+018x31A,
=o
aed :
Dre en
CORTE cPse={-o2re2+o1eeaa,
“064, Bm
From these calculatonsiis observed that CESE for Mn * in octahedra fields highest, therefore it
willbe stabilized in octahedral voids. Thus, Ma ** will occupy the octahedral voids and the Ma" ion
wil ocpuy Ue aa vis, ad hee Mn O, is normal spel
Dam
(300304 Ent, 0,
Co is low spin in the field produced | by oxide ions.
Ostaheral Teteaherat
coté e ee
CESE=(-06=4+06x0J0, CESE=[-027x3+018x3)A,
=-248, OS +054),
“azra
otal) bd
CPSE=[-04x5+06x2JA,
“188,
‘Since CFSE forCo** is highest in octahedral feld.
‘Therefore,Co* will occupy octahedral and Co” will occupy terahedral voids. Hence Co30, isa
= [027 440183},
0548,
normal sine.
ma
(6) Fes0,—+ Fefe¿04
Octahedrat Tetrabedrnl
EA ez
CFSE=(-04%3+06X2JA, CFSB=1-027%2+018%3]40
=0
ras) A à 38
Bea, ed
CESE=[-04x4+06x2A, CESE=[-027 <3+0IS AMA,
048, 02740
Since CFSE fr Fe” in octahedral fet is highest.
‘Therefore, Fe?* jon wil occupy octahedral voids and Fe** ions occupy teiahedrl voids and
‘ctahedral void. Thus, Fe30g isan inverse spinel
n 48) NiFe 204
i Octahedrat Teteabedrat
ES en
crse=0
oo,
046 +0642}85 CASE = [=027 4 +018 a ==
128, 2203640 E
Since CESE fr N?" oni highest in calor! ld. Therefore Non wil copy cate
void and Fe™ wil occupy both erhedral and octahedra voids, Ths,NiFe 04 iseninvetespine
Most ofthe pies having Fe?" oes are inverse spinel. Fe?" ion witha ofiguration as CESE
‘qual to zero in bth be ocaedra and etahea! voids. A dipositive ion isthe spel wil have rete
y CESE in octahedral fl la tht in tetrahedral geomeiry because the crysis Held sping in
| seeaedalgeomery is 48 hat of he equivalent octahedral environment Tus e dose en wil
prefer ocapy the ota voids,
Note: Ifwecafeulate CFSE or AT" and BŸ* ons in any ocahodrl fe thn its ogctude at
¡CESE of B™ ishigher tn hat A, he spinel willbe normal piel. HE CFSE of A is higher
than hat of B*, then the spinel wl be inverse spi!
whereas the other hal of à
un wen
representadas! B LA BO.
Example of inverse spinels re CrFe 04, e304, Nife04, Mpeg, NALO ee
In general, th spines having Fe ons are iver spinels
Predicting the Structure of Spinels
‘An important factor in detemining whether a spinel is normal or averses the CESE ofthe cations
‘occupying the erahedral and octabedral voids. The metal ction in tetrahedral and octet voids are
surrounded by four and six oxide ons respectively. Thus, Ue metleations occupying the erhedeal
and octahedra voids are considered to form tetrahedral and octahedsal complexes respectively. The
‘oxide ion bebaves asa weak ligand. To determine whether a spine i normal or inves, we ave to
compare the CESE in octahedral and tetakedral environment for both A2 and ions. IF CFSE for
13°" ion in octahedral vids ws preter than that of Bin tetrahedral and A in bth he tetrabodal and
octahedrl voids, the spinel wil be normal.
AT CESE for A ion in octahedra void is greater than A2* in tttaedral and BP" in both the
tetrchedral and octahedral void, ten the spine wil be inverse
Examples
wm
330,0,
(0 behaves as a weak ligand.
„Set Tetcabedral
Mo?) ef en
CFSE =[-04x3+06x2)A, CFSE=[-027x2+018x31A,
=o
aed :
Dre en
CORTE cPse={-o2re2+o1eeaa,
“064, Bm
From these calculatonsiis observed that CESE for Mn * in octahedra fields highest, therefore it
willbe stabilized in octahedral voids. Thus, Ma ** will occupy the octahedral voids and the Ma" ion
wil ocpuy Ue aa vis, ad hee Mn O, is normal spel
Dam
(300304 Ent, 0,
Co is low spin in the field produced | by oxide ions.
Ostaheral Teteaherat
coté e ee
CESE=(-06=4+06x0J0, CESE=[-027x3+018x3)A,
=-248, OS +054),
“azra
otal) bd
CPSE=[-04x5+06x2JA,
“188,
‘Since CFSE forCo** is highest in octahedral feld.
‘Therefore,Co* will occupy octahedral and Co” will occupy terahedral voids. Hence Co30, isa
= [027 440183},
0548,
normal sine.
ma
(6) Fes0,—+ Fefe¿04
Octahedrat Tetrabedrnl
EA ez
CFSE=(-04%3+06X2JA, CFSB=1-027%2+018%3]40
=0
ras) A à 38
Bea, ed
CESE=[-04x4+06x2A, CESE=[-027 <3+0IS AMA,
048, 02740
Since CFSE fr Fe” in octahedral fet is highest.
‘Therefore, Fe?* jon wil occupy octahedral voids and Fe** ions occupy teiahedrl voids and
‘ctahedral void. Thus, Fe30g isan inverse spinel
n 48) NiFe 204
i Octahedrat Teteabedrat
ES en
crse=0
oo,
046 +0642}85 CASE = [=027 4 +018 a ==
128, 2203640 E
Since CESE fr N?" oni highest in calor! ld. Therefore Non wil copy cate
void and Fe™ wil occupy both erhedral and octahedra voids, Ths,NiFe 04 iseninvetespine
Most ofthe pies having Fe?" oes are inverse spinel. Fe?" ion witha ofiguration as CESE
‘qual to zero in bth be ocaedra and etahea! voids. A dipositive ion isthe spel wil have rete
y CESE in octahedral fl la tht in tetrahedral geomeiry because the crysis Held sping in
| seeaedalgeomery is 48 hat of he equivalent octahedral environment Tus e dose en wil
prefer ocapy the ota voids,
Note: Ifwecafeulate CFSE or AT" and BŸ* ons in any ocahodrl fe thn its ogctude at
¡CESE of B™ ishigher tn hat A, he spinel willbe normal piel. HE CFSE of A is higher
than hat of B*, then the spinel wl be inverse spi!
Bean
aa
Limitations of Crystal Field Theory
Crystal field theory explain successfully the structures of complexes, magnetic properties, colour
and eleczonie spectra, thermodynamic and kinetic aspects ofthe complexes. However, this theory bas
some serous imitations.
(1) CFT oonsiers only the metal d- orbitals and s-and p- orbitals are ignored.
(0) This theory tas not considered the covalent character in transition metal complexes.
(© CFT ha also not considered the rebonting (ether the M -» or LM) in complexes.
(8) CFT can not explain the relative strength of ligands as given in sectochemical eis
(5) The compounds le Cr (CO), Ni (CO) in which metal is in zero oxidation state and the ligand is
uta have no electrostatic attraction between the metal andthe ligando.
Evidence for Metal Ligand Covalent Bonding in Complexes
(0 Cr(CO)e is a volatile compound and Ni(CO)4 is iguic, This indie that there is covalent
‘wonding between metal and the ligands instead of the ionic [ee would ine bond, then
CACO)E shuld be nonvolatile and Ni(CO) solid
(2) The Electron Spin Resonance (ESR): The ESR spectrum of Cle] suggests thatthe single
‘pied electron s only 70% locas om the metal stom, and about 30% is Locale onthe
1 of electron and bene some covalency between
ligands.
1) The Nuclear Magnetic Resonance (NMR) : The fluorine NMR has detected the delocalization of
lect in he fluor complexes, of paramagnetic metal ico. es posible oly when an unpaired
lector spends more ha negligible time on ! F nucleus —
(9 TheNephelanxtie Rect: “Theetectonirepuision ind: obits ofuansicametacatons give
vis to a number of energy leeis depending upon the arangement ofthe eetrns inde orbital,
‘The energy difference between two energy sites can be expressed in terms of itereecto
repulsion parameters, called the Racah parameters B an C Th difrencein energy between two
levels having same spin mulipliity.can be expressed in terms of only B, aif the diference in
exery between two energy levels having diferen sp rulplisis can beexpresed in tems of
B and C. It is observed experimentally (ie. for electronic spec of complexes) tat the
rapide of Band C decreases when the complex is formed, Te reed value of 4 and C
Ins een dee edad on mea can EE. Kern dd Rd ve
both the metal cation andthe ligands. This suggest that hee is some covalrey between metal
cation andthe ligands. The mor he value of and Cis reduced, be reste e delocatizaton of
lesion lw andthe greste the covaeney. The elocalizaion o electron coud over mea ation
andthe ignds sealed the rephelauxetc effect.
(6) Nuclear Quadrupole Resonance (NQR) : The NOR spectum of some complexes containing
aidons as igands like [PCI [PAC suggests thatthe tal igand bood is party io
aptly covalent
Ligand Field Theory
Cipsa fed theoryhas treated ligands as point charged dipoles and does notte into account the
covaleatboodingincomplers.Insead repars the bonding purely oí The physical measurements
such as lecron sin resonance (ESR) o electron paragaci resonnce (EPR), nuclear magnetic
resonarce (NMR), nuclear quadrupole resonance (NOR) and Raca parameters calculations from
stone spect give evidence in favo of covalet bonding in epodiraton compounds.
The couler boning in complexes hasbeen explained by ligacd fl theory (LET). According to
ligand ie deny covalent bonds between metal and ligands are armed bythe near combinations of
be metal atome obits and ligand group orbitals (LG). The sjmmees of ligand group orbitals
must e symmetries ofthe metal atomic orbital sch that ers positive ovelpping of LGOs
vih mea ls along the bonding axes.
Sigma Bonding in Octahedral Complexes
In octaedal complexes, the ligands are approaching (be metal cation on x, y- and 2- axes
‘Therefore LGOs willovertap with metal orbital along the octahedral bonding axes to forenc-bonds. The
metal cation has, in its valence shell, one ns, three np and five (m ~ 1) d- orbitals. The octahedral
symmetry bas tansformed sorbtal into arg, p-orbitls ito ty, dy, dye 20 de orbital into (y and
dj and 2 oils into eg ses.
Metal orbital Symmetry
PoPp Ps ta
Aap dyes de te
da pla e
Sins bistec in shape here ten veg with LGOS on lies The u and
ils one sone ae. Treo hs bill canine osier ae by
vtgpngwihLGOs. The orbitals ein betwee the es, es, tee ba ar not capable
twovetap i LGOst (om bons. Therefore ot ofthe nine mal noni (neg the
fa an 0) bals parcipat in = bond formation. The fag ei ae considered to be non
bording leur oils in octal conpenes whee tee iso posi of wbonding he
ligands ave alo same syumety as dat of meal gobi, te ag metal tal val be
invlvedins bond
Now he queso ais hat what are the LGOS nd ow cn thee be const? Each fhe ix
equivalent land tos conus an atomic orbital ar Hd tom cloro. aan
caballa, escama tri octal sanar oi ag 03,
«rad ees VA ave been eprseted as Gand os tnd 0. reine
god,
aa
Limitations of Crystal Field Theory
Crystal field theory explain successfully the structures of complexes, magnetic properties, colour
and eleczonie spectra, thermodynamic and kinetic aspects ofthe complexes. However, this theory bas
some serous imitations.
(1) CFT oonsiers only the metal d- orbitals and s-and p- orbitals are ignored.
(0) This theory tas not considered the covalent character in transition metal complexes.
(© CFT ha also not considered the rebonting (ether the M -» or LM) in complexes.
(8) CFT can not explain the relative strength of ligands as given in sectochemical eis
(5) The compounds le Cr (CO), Ni (CO) in which metal is in zero oxidation state and the ligand is
uta have no electrostatic attraction between the metal andthe ligando.
Evidence for Metal Ligand Covalent Bonding in Complexes
(0 Cr(CO)e is a volatile compound and Ni(CO)4 is iguic, This indie that there is covalent
‘wonding between metal and the ligands instead of the ionic [ee would ine bond, then
CACO)E shuld be nonvolatile and Ni(CO) solid
(2) The Electron Spin Resonance (ESR): The ESR spectrum of Cle] suggests thatthe single
‘pied electron s only 70% locas om the metal stom, and about 30% is Locale onthe
1 of electron and bene some covalency between
ligands.
1) The Nuclear Magnetic Resonance (NMR) : The fluorine NMR has detected the delocalization of
lect in he fluor complexes, of paramagnetic metal ico. es posible oly when an unpaired
lector spends more ha negligible time on ! F nucleus —
(9 TheNephelanxtie Rect: “Theetectonirepuision ind: obits ofuansicametacatons give
vis to a number of energy leeis depending upon the arangement ofthe eetrns inde orbital,
‘The energy difference between two energy sites can be expressed in terms of itereecto
repulsion parameters, called the Racah parameters B an C Th difrencein energy between two
levels having same spin mulipliity.can be expressed in terms of only B, aif the diference in
exery between two energy levels having diferen sp rulplisis can beexpresed in tems of
B and C. It is observed experimentally (ie. for electronic spec of complexes) tat the
rapide of Band C decreases when the complex is formed, Te reed value of 4 and C
Ins een dee edad on mea can EE. Kern dd Rd ve
both the metal cation andthe ligands. This suggest that hee is some covalrey between metal
cation andthe ligands. The mor he value of and Cis reduced, be reste e delocatizaton of
lesion lw andthe greste the covaeney. The elocalizaion o electron coud over mea ation
andthe ignds sealed the rephelauxetc effect.
(6) Nuclear Quadrupole Resonance (NQR) : The NOR spectum of some complexes containing
aidons as igands like [PCI [PAC suggests thatthe tal igand bood is party io
aptly covalent
Ligand Field Theory
Cipsa fed theoryhas treated ligands as point charged dipoles and does notte into account the
covaleatboodingincomplers.Insead repars the bonding purely oí The physical measurements
such as lecron sin resonance (ESR) o electron paragaci resonnce (EPR), nuclear magnetic
resonarce (NMR), nuclear quadrupole resonance (NOR) and Raca parameters calculations from
stone spect give evidence in favo of covalet bonding in epodiraton compounds.
The couler boning in complexes hasbeen explained by ligacd fl theory (LET). According to
ligand ie deny covalent bonds between metal and ligands are armed bythe near combinations of
be metal atome obits and ligand group orbitals (LG). The sjmmees of ligand group orbitals
must e symmetries ofthe metal atomic orbital sch that ers positive ovelpping of LGOs
vih mea ls along the bonding axes.
Sigma Bonding in Octahedral Complexes
In octaedal complexes, the ligands are approaching (be metal cation on x, y- and 2- axes
‘Therefore LGOs willovertap with metal orbital along the octahedral bonding axes to forenc-bonds. The
metal cation has, in its valence shell, one ns, three np and five (m ~ 1) d- orbitals. The octahedral
symmetry bas tansformed sorbtal into arg, p-orbitls ito ty, dy, dye 20 de orbital into (y and
dj and 2 oils into eg ses.
Metal orbital Symmetry
PoPp Ps ta
Aap dyes de te
da pla e
Sins bistec in shape here ten veg with LGOS on lies The u and
ils one sone ae. Treo hs bill canine osier ae by
vtgpngwihLGOs. The orbitals ein betwee the es, es, tee ba ar not capable
twovetap i LGOst (om bons. Therefore ot ofthe nine mal noni (neg the
fa an 0) bals parcipat in = bond formation. The fag ei ae considered to be non
bording leur oils in octal conpenes whee tee iso posi of wbonding he
ligands ave alo same syumety as dat of meal gobi, te ag metal tal val be
invlvedins bond
Now he queso ais hat what are the LGOS nd ow cn thee be const? Each fhe ix
equivalent land tos conus an atomic orbital ar Hd tom cloro. aan
caballa, escama tri octal sanar oi ag 03,
«rad ees VA ave been eprseted as Gand os tnd 0. reine
god,
are 195 hi chain
Theo p.00 ander otilsofliand ar combined toga lineal to foma et
afliga row riel of he require metes tooveap is, ande orbital ofa
Since he wave untion ayy cria hs same sign wich itakmtnbe pie every where. The
si ges, therefore, can ovrlap equal with hs oil nd cach gad oral must also have
sive sgn. Thu, a ligand group eri en be const y native ica combination ofthe
sic ligand obits
fay eh 140-140, 10-p 010-2 ay
1 ion cons
Whee isanomala
ligand obits
Since wave function of one lobe of eachof the py py and pb as positive sigs and the other
tas negative sign, Therefore,
nd Zand o are the wavefuncions of LGO and contributing
‘The wo opposite lobes of 2 orbitals have postive sign andthe other two opposite lobes have
negative sign. Therefore,
Bap here
9)
Theo p.00 ander otilsofliand ar combined toga lineal to foma et
afliga row riel of he require metes tooveap is, ande orbital ofa
Since he wave untion ayy cria hs same sign wich itakmtnbe pie every where. The
si ges, therefore, can ovrlap equal with hs oil nd cach gad oral must also have
sive sgn. Thu, a ligand group eri en be const y native ica combination ofthe
sic ligand obits
fay eh 140-140, 10-p 010-2 ay
1 ion cons
Whee isanomala
ligand obits
Since wave function of one lobe of eachof the py py and pb as positive sigs and the other
tas negative sign, Therefore,
nd Zand o are the wavefuncions of LGO and contributing
‘The wo opposite lobes of 2 orbitals have postive sign andthe other two opposite lobes have
negative sign. Therefore,
Bap here
9)
TZ
MO ARA
‘The d,2 orbital is obtained by the combination of two dependent orbitals viz. d,
ra dans
‘Thed 2 is tua thed,, 2. > Therefor, the LGO that match thed > orbital corresponds tothe
LE
wid z
By Sg te -0,-01-0,-0.)
“The LGOs with ber symmetry mache wi meta ias ae shown in Figure 420.
‘These six combinations account or al gandorbitals t be of o- symmetry. Non of thse LOs
ave the symmetry of mea fg ra, therefor the er do no participate ordi,
From the syto properties of ocur complexe it is observed at nta! ná ign y
cbt wil over to givetwowolecuaoials(onebonding cy and one atbonding a) ein
degenerate metal and liga orbitals wil ova to gie sc molecular exit (Bree degenerate
bonding, u and three degenerate antibonding) he doubly degemerte met! ná igand e oils
will vec o give four moler oil (vo degenerate boning, ey and two degennte
aotionding, 7) Therefore, thee ae six oadng nd si antibonding molecular obi. athe yt
without bonding, te thee wily degenerate metal, abi ar non honding and have sme nergy
asin fee metal cation The overlap oa ay and rials wth LOS is mre extemive than ht of
gobi, therefore hee ar large ren in energy beeen the resulting ay an and and
di bonding and antibonding molecular ois. Terre, the ay and ja bonding molecular ral
arelowestinenergyand aj, and, antibonding molecular obit are 0
iahescenery, The gg ande
reculer orbitals have ss ee dieron ects of poorer overlap between the mel and ligand
obits. Therefore, we can sy amore, ger willbe the separation and more wi o
covalen¢ character.
The energy rence been fg aná mole obit sequal oA a ven bythe en
field theory. aa ne
Its assumed hat a isn molar bal has th character associated withthe sonics
wich is nearest in energy, For wos ofthe gun, igandso orias ae derived om he tonic
ofits which bae lower energies dan de metal doi. Therefor, ie six bonding molar
bals (on ay ep nd 0, bin) ofthe cada complex have primary he chamcerat
ligand oil Dt also have some characte oft! rial rm which they are derive, oc he
ligand do tak ono the meta con oatom, On he oer hand, the antibonding lecular obits,
oi and 1, uv mainly he character ofcomsponting mel rial bu se sme! lacie on
the ligands. Since te 2, orbital ae ot involved boning, therefore, these are non-bonding ad
ei energy is same as in free metal cation, These bals have pure metal d- orbitals caracter In
sahedel complexes, th sx ligands provide sx pairs of electrons which ll are accommodated in the
bondi molecular ota These clacton ae ail retina onto the ind in th comple, justas
describe by the CFT. Ina he ixpaisofeectrn provided by the ligands, er ill aways be
4 leon available ont! tom oration which oecuy he non-bonding andthe anioning
ef bits. The lens provided byte meta on etn mainly ont the metal ion. The disbuion
ofthe metal de lens in fg and ef obs are similar as described by the CFT bat he basi
free is tatinihe LT the gan nialsare nt confined completely tthe melon whereas
in the CFT the ¢-lerons ae completely confined tothe metal on.
Jn an octahedra comple, the att 12 4 letons oe placed in oct whee
d" respresents the number of metal de electrons. The distribution of 12 + 4" electrons in molecular
als wil be
Let (where pra=n
re rm ar bencina in acaba crises:
‘The LET also give the interpretation of high spin and low spin complexes depending on the
magnitude ofA, and the paring energy whichis similar to that given by the CET.
For low spin complexes, A, > P
For high spin complexes, A < P
MO ARA
‘The d,2 orbital is obtained by the combination of two dependent orbitals viz. d,
ra dans
‘Thed 2 is tua thed,, 2. > Therefor, the LGO that match thed > orbital corresponds tothe
LE
wid z
By Sg te -0,-01-0,-0.)
“The LGOs with ber symmetry mache wi meta ias ae shown in Figure 420.
‘These six combinations account or al gandorbitals t be of o- symmetry. Non of thse LOs
ave the symmetry of mea fg ra, therefor the er do no participate ordi,
From the syto properties of ocur complexe it is observed at nta! ná ign y
cbt wil over to givetwowolecuaoials(onebonding cy and one atbonding a) ein
degenerate metal and liga orbitals wil ova to gie sc molecular exit (Bree degenerate
bonding, u and three degenerate antibonding) he doubly degemerte met! ná igand e oils
will vec o give four moler oil (vo degenerate boning, ey and two degennte
aotionding, 7) Therefore, thee ae six oadng nd si antibonding molecular obi. athe yt
without bonding, te thee wily degenerate metal, abi ar non honding and have sme nergy
asin fee metal cation The overlap oa ay and rials wth LOS is mre extemive than ht of
gobi, therefore hee ar large ren in energy beeen the resulting ay an and and
di bonding and antibonding molecular ois. Terre, the ay and ja bonding molecular ral
arelowestinenergyand aj, and, antibonding molecular obit are 0
iahescenery, The gg ande
reculer orbitals have ss ee dieron ects of poorer overlap between the mel and ligand
obits. Therefore, we can sy amore, ger willbe the separation and more wi o
covalen¢ character.
The energy rence been fg aná mole obit sequal oA a ven bythe en
field theory. aa ne
Its assumed hat a isn molar bal has th character associated withthe sonics
wich is nearest in energy, For wos ofthe gun, igandso orias ae derived om he tonic
ofits which bae lower energies dan de metal doi. Therefor, ie six bonding molar
bals (on ay ep nd 0, bin) ofthe cada complex have primary he chamcerat
ligand oil Dt also have some characte oft! rial rm which they are derive, oc he
ligand do tak ono the meta con oatom, On he oer hand, the antibonding lecular obits,
oi and 1, uv mainly he character ofcomsponting mel rial bu se sme! lacie on
the ligands. Since te 2, orbital ae ot involved boning, therefore, these are non-bonding ad
ei energy is same as in free metal cation, These bals have pure metal d- orbitals caracter In
sahedel complexes, th sx ligands provide sx pairs of electrons which ll are accommodated in the
bondi molecular ota These clacton ae ail retina onto the ind in th comple, justas
describe by the CFT. Ina he ixpaisofeectrn provided by the ligands, er ill aways be
4 leon available ont! tom oration which oecuy he non-bonding andthe anioning
ef bits. The lens provided byte meta on etn mainly ont the metal ion. The disbuion
ofthe metal de lens in fg and ef obs are similar as described by the CFT bat he basi
free is tatinihe LT the gan nialsare nt confined completely tthe melon whereas
in the CFT the ¢-lerons ae completely confined tothe metal on.
Jn an octahedra comple, the att 12 4 letons oe placed in oct whee
d" respresents the number of metal de electrons. The distribution of 12 + 4" electrons in molecular
als wil be
Let (where pra=n
re rm ar bencina in acaba crises:
‘The LET also give the interpretation of high spin and low spin complexes depending on the
magnitude ofA, and the paring energy whichis similar to that given by the CET.
For low spin complexes, A, > P
For high spin complexes, A < P
Order of Energies of Molecular Orbitals and Distribution of Electron in chem
(a) Forlow spin complex, the magnitude of 4 y ¡sarge enough. Therefore, he energies of molecular
‘orbitals follow he onder
aie < he < epg <6 < où < the
For example, the complex (Co(NH3)6}"* which is a low spin complex have total 18 valence
‘electrons : 12 from the six NH; ligands and the six are metal d-clectrons, The electronic
eof is
dass
ie te
9) Forkigh spincomplexes,themagitnde of, is smal, therefore, the energies of te ande} obs
are sum to besa. Therefor, energies of molecular bil ofligh ia rapes fellow
thea:
eX tn ch cé éd ci
For example, for[CoF6]”” complex ion, which is a high spin complex, there are total 18 clectrons in
valence ill Fortis compl electo distrib s :
RTE
ie Me Ee E
Fig 421 its al dal complexes shold have, in aon ins,
as oe ligand mea charge anfr band Le, tans of a ton rm pedanany ad
bias promienty meta ob. The nese charge tant bends se nein UV ar ome
times in vl egon any ol comesponding o ansons fees at, or
boto here his
x Bonding in Octahedral Complexes
An détient met lig ers many pans which have fiat syne wit
eset 1 cha ses, capable für x bonding interaction with he et to e ein. The
‘honing wile pif if melt and land oa ave pop unto, capable se
tad energy, Temi ada vaa in bonding ar paper eM Lac. in
on eee ee a 12 ad go als capable of irn These LGO log
1 fur pre ae 34 a: On te ter Hane on me eon a ae
ctu complex as wo ps fois (hy nd) ich ar cont year bug.
The tg and and group ob ae non boing because ter re no etal fa of bese
sya, The mel bts 4 mme are drid atthe gars an, eee vale ing
Bonn, er es sar mane fr onding The Hand o al and
metal ral fhe ane syne e, y) an form mctabigand elo: oi Ge, ire
Sontag meter als andres atbnding moles as) - The bonding molar
cris, ar flore de og eel ls (te it tan
the omic els Bath being nd bno molecular cias rt desert
TAS eA a a E EEE STEEL,
In octal complexes th ligand group oials corresponding 43, symmetry may be px da
ora Therefore, thee may be ourtypes of intactos: (Dd pei) dn Ai) di— and
Were".
0) 42 pr Bonding + In this ype of xbonding, the ligand group obits are formed by
cofbinations ofp ois pependicularto: bond axes of donor toms of ganas Fire 4222), The
d- prbonds se ore by donation of electrons for pr xt flans empty de obits of
the metal. The px obits ar always filed and are found ia FC, Br”,I,0,RO™RS™ et
Dd x~ dxBonding: Indn- drbonding ie filled derbi of etl overlap withthe empty d-
‘orbital ofthe igand (Figure 422). The ligands such as RoP, AS. RyAsbave the empty de orbitals
ON .
Vi) da +" Bonding : The dan” bonds ae formed when filed de artis of mea con or
om sera with empty x ( anbondig) ofthe ligands. The ligado having he empty xi
areCO,CN", po peral, ethylene, Na, NOZ ete.
042-0" Bonding: Theda" bonds are formed whenthe fiestas ofthe metal cation
overlap with the eaptye-enibonding ("ofthe ligands. The lignée sing the empty” orbials are
Hp, RyB, lkaeset. In Ry thea orbitals are of PC bonds.
“
>) H
“ “
an Figure 422 (a) d=- prbonding (0) d xd 000
A EA bonding de ne ieee
Abe ia orale fd and se of owes energy tha party fll tal tg bi en
Gear cs rea ith etal ng tat give boning y moler, ty)
oflower nergy tan LGOs ad ainia molecular cial, higher ce ave othe
sos Boing y cis ofe-boding complex. The ligand having ile, LOO floue ng
than the metal d obit ae E”, CI”, Br” I, Hz0,$*'ete. These ligands having filed tng LGOs are
called x oni, ithe LGOs ar of lower energy thn th eal fg atl, rr,
‘ending ness have the charter of.GOs anh nibonding moot save
characte lig obi Therefore telson supplied bythe ligas oil wl fl thew
tenting lea els and he lerons fom the me fg bil wl fil de € ntbendng
(a) Forlow spin complex, the magnitude of 4 y ¡sarge enough. Therefore, he energies of molecular
‘orbitals follow he onder
aie < he < epg <6 < où < the
For example, the complex (Co(NH3)6}"* which is a low spin complex have total 18 valence
‘electrons : 12 from the six NH; ligands and the six are metal d-clectrons, The electronic
eof is
dass
ie te
9) Forkigh spincomplexes,themagitnde of, is smal, therefore, the energies of te ande} obs
are sum to besa. Therefor, energies of molecular bil ofligh ia rapes fellow
thea:
eX tn ch cé éd ci
For example, for[CoF6]”” complex ion, which is a high spin complex, there are total 18 clectrons in
valence ill Fortis compl electo distrib s :
RTE
ie Me Ee E
Fig 421 its al dal complexes shold have, in aon ins,
as oe ligand mea charge anfr band Le, tans of a ton rm pedanany ad
bias promienty meta ob. The nese charge tant bends se nein UV ar ome
times in vl egon any ol comesponding o ansons fees at, or
boto here his
x Bonding in Octahedral Complexes
An détient met lig ers many pans which have fiat syne wit
eset 1 cha ses, capable für x bonding interaction with he et to e ein. The
‘honing wile pif if melt and land oa ave pop unto, capable se
tad energy, Temi ada vaa in bonding ar paper eM Lac. in
on eee ee a 12 ad go als capable of irn These LGO log
1 fur pre ae 34 a: On te ter Hane on me eon a ae
ctu complex as wo ps fois (hy nd) ich ar cont year bug.
The tg and and group ob ae non boing because ter re no etal fa of bese
sya, The mel bts 4 mme are drid atthe gars an, eee vale ing
Bonn, er es sar mane fr onding The Hand o al and
metal ral fhe ane syne e, y) an form mctabigand elo: oi Ge, ire
Sontag meter als andres atbnding moles as) - The bonding molar
cris, ar flore de og eel ls (te it tan
the omic els Bath being nd bno molecular cias rt desert
TAS eA a a E EEE STEEL,
In octal complexes th ligand group oials corresponding 43, symmetry may be px da
ora Therefore, thee may be ourtypes of intactos: (Dd pei) dn Ai) di— and
Were".
0) 42 pr Bonding + In this ype of xbonding, the ligand group obits are formed by
cofbinations ofp ois pependicularto: bond axes of donor toms of ganas Fire 4222), The
d- prbonds se ore by donation of electrons for pr xt flans empty de obits of
the metal. The px obits ar always filed and are found ia FC, Br”,I,0,RO™RS™ et
Dd x~ dxBonding: Indn- drbonding ie filled derbi of etl overlap withthe empty d-
‘orbital ofthe igand (Figure 422). The ligands such as RoP, AS. RyAsbave the empty de orbitals
ON .
Vi) da +" Bonding : The dan” bonds ae formed when filed de artis of mea con or
om sera with empty x ( anbondig) ofthe ligands. The ligado having he empty xi
areCO,CN", po peral, ethylene, Na, NOZ ete.
042-0" Bonding: Theda" bonds are formed whenthe fiestas ofthe metal cation
overlap with the eaptye-enibonding ("ofthe ligands. The lignée sing the empty” orbials are
Hp, RyB, lkaeset. In Ry thea orbitals are of PC bonds.
“
>) H
“ “
an Figure 422 (a) d=- prbonding (0) d xd 000
A EA bonding de ne ieee
Abe ia orale fd and se of owes energy tha party fll tal tg bi en
Gear cs rea ith etal ng tat give boning y moler, ty)
oflower nergy tan LGOs ad ainia molecular cial, higher ce ave othe
sos Boing y cis ofe-boding complex. The ligand having ile, LOO floue ng
than the metal d obit ae E”, CI”, Br” I, Hz0,$*'ete. These ligands having filed tng LGOs are
called x oni, ithe LGOs ar of lower energy thn th eal fg atl, rr,
‘ending ness have the charter of.GOs anh nibonding moot save
characte lig obi Therefore telson supplied bythe ligas oil wl fl thew
tenting lea els and he lerons fom the me fg bil wl fil de € ntbendng
an
hls The ep evils ar not ected by mboning and fg mel rials becomes antibonding and
Ihence are aise closer in energy tothe metal ez antibonding orbitals. Thus, the energy difference, & 5
Lee, ande} deceasesrlativet the iicnce were mei gant
bonding does not exist. The
ses Ay is smaller for OH” ligands compared to HO becuase OH" isa better n-donor.
roe
“ u 1502
Area
Afin and oils are empty ndo ger cs tha em port le ral, then
pi ng olas overs wth metal y oil 0 give bondi and nes leas cal.
and having emp fg tas of ie iger enn ana of fe metal coa are
LP, Ry As, RoS (with vacant d- orbitals) and CO, CN™,NO*, phen, N; (with vacant n° orbitals) etc.
course these ligands with vacant x” orbitals also have filled x orbitals and can function ase donor
‘because of very low energy these orbitals can not overlap with metal d- orbitals. These ligands with
1 ng ba recalled ccptr guns. ince the LOOsbave igh cory han at of tal
oils, cts, bonding molecular obi ave the chance of mel e abs and the
Ponting mous oil have the claras of LGOS, The aking tang ils are
ale over bath metal and igands which wee the on-Dondng and cazo on mel in he
oe 0 bonding Since he bonding molecular which have te cance of mel il are
sd ner s compar tthe peril ine absence of Doing Tief, ney
rate A besten lng bonding and 7 atboing abs is increased rave 0 he diecace
ere ML ding dos not exit The energy ol oi lo higher than hat of orita
‘sete con Som metal d orbital are le iin, and den nc bi
Peares:
The liga Geld theory explain the order of ligand ia spectrochemical sesos from weaker 0
stronger. When x= bonding is significant, it has been observed that the ligands such as halides,
$?" SCN" which ae strong -donor decrease 4, an the r aoceptr ligands ike CO,CN Ry, NOZ
cle whichare tong x acceptors increase à, relative tot Ag where there iso bonding, Therefore,
the tong dono ligands are atthe weak end and te ligand which are strong, x- aceptor fie atthe
strong. end ofthe spectrochemical series. The ligands having litle or no x - bonding ability have
intermediate valu of y and lie in the middle of he specttocberical seres, Ths, ha been concluded,
thatthe value OÍ, increases in the order of : - donoc < weak. donor <ncither == donor nor
‘acceptor < weak a aceptor < strong - acceptors Je jones ww
LB << F< OH” <0? < HO < py, Nils <em <
Sn dat © Weak dom Ce
‘py, phen < NO} < PPh < CH5,H” <CN”,00
keep Snonga-aner ep CH a
{athe pectrochemicat series the ligands CH and H™ ligands are neither n- donor nor strong =
acces, yet thy are very igh in spoctrochemical series. The reasons thatthese are strong donors
‘Sigma Bonding in Tetrahedral Complexes
“The procedure fer the constitution of molecular orbital ingrams fr tetrahedrl and square planar
complexes is same as that applied for octahedral complexes. The metal atom r ion in cach case uses its
hls The ep evils ar not ected by mboning and fg mel rials becomes antibonding and
Ihence are aise closer in energy tothe metal ez antibonding orbitals. Thus, the energy difference, & 5
Lee, ande} deceasesrlativet the iicnce were mei gant
bonding does not exist. The
ses Ay is smaller for OH” ligands compared to HO becuase OH" isa better n-donor.
roe
“ u 1502
Area
Afin and oils are empty ndo ger cs tha em port le ral, then
pi ng olas overs wth metal y oil 0 give bondi and nes leas cal.
and having emp fg tas of ie iger enn ana of fe metal coa are
LP, Ry As, RoS (with vacant d- orbitals) and CO, CN™,NO*, phen, N; (with vacant n° orbitals) etc.
course these ligands with vacant x” orbitals also have filled x orbitals and can function ase donor
‘because of very low energy these orbitals can not overlap with metal d- orbitals. These ligands with
1 ng ba recalled ccptr guns. ince the LOOsbave igh cory han at of tal
oils, cts, bonding molecular obi ave the chance of mel e abs and the
Ponting mous oil have the claras of LGOS, The aking tang ils are
ale over bath metal and igands which wee the on-Dondng and cazo on mel in he
oe 0 bonding Since he bonding molecular which have te cance of mel il are
sd ner s compar tthe peril ine absence of Doing Tief, ney
rate A besten lng bonding and 7 atboing abs is increased rave 0 he diecace
ere ML ding dos not exit The energy ol oi lo higher than hat of orita
‘sete con Som metal d orbital are le iin, and den nc bi
Peares:
The liga Geld theory explain the order of ligand ia spectrochemical sesos from weaker 0
stronger. When x= bonding is significant, it has been observed that the ligands such as halides,
$?" SCN" which ae strong -donor decrease 4, an the r aoceptr ligands ike CO,CN Ry, NOZ
cle whichare tong x acceptors increase à, relative tot Ag where there iso bonding, Therefore,
the tong dono ligands are atthe weak end and te ligand which are strong, x- aceptor fie atthe
strong. end ofthe spectrochemical series. The ligands having litle or no x - bonding ability have
intermediate valu of y and lie in the middle of he specttocberical seres, Ths, ha been concluded,
thatthe value OÍ, increases in the order of : - donoc < weak. donor <ncither == donor nor
‘acceptor < weak a aceptor < strong - acceptors Je jones ww
LB << F< OH” <0? < HO < py, Nils <em <
Sn dat © Weak dom Ce
‘py, phen < NO} < PPh < CH5,H” <CN”,00
keep Snonga-aner ep CH a
{athe pectrochemicat series the ligands CH and H™ ligands are neither n- donor nor strong =
acces, yet thy are very igh in spoctrochemical series. The reasons thatthese are strong donors
‘Sigma Bonding in Tetrahedral Complexes
“The procedure fer the constitution of molecular orbital ingrams fr tetrahedrl and square planar
complexes is same as that applied for octahedral complexes. The metal atom r ion in cach case uses its
lion Chen.
“Ties fc el Ligand Bondi in Conia
Be
sume nine valence orbital available for bonding ut tee syn properties are different for each
geometry. Fora tetrahedral ML complex, the metal s and poils have ay and f2.symeties
repectvely. The dy dye and dar ovis aver and d'y add riss have espanto, tis
seenthatthe symmetries ofp-rbitlsand hat fd, dy and oil are identical et symnety.
“isd tthe fact that th orbitals iyidzed with bit (Ayo) and dy, d andar
oral hybridized with sofa (hybrid) frm teeabedralgeontery. OF the four Hand
group abials (LG0s) constucted fom ligand loue pair bias one have a and thes have 7
smmeties. The ay orbital LGO interacts with a, esl of meal o give one bonding ard one
antibonding MO and 13 LGOS can interact with bob ses of obialsofmeal (Pand day, d, do
site one bonding and two antibonding molecular bs (Fig, 425). In contas o he ocak
complexes, he meta orbitals re non-boning The separo between thee andthe nex high 2
lecular onal i equal to, as in CFT For a complex sch as (CaC fer ar oa Gen
valen electors of which cigh electron ae produced by four igand (wo electrons per Tigan) and
‘the Ca? (4” ion finishes seven electron. Bight electron ac ld in the banding MOS (a an 1),
four clans in non bonding e obits and tre in he slightly aasbondig > octal.
25 MO itiggram for booting ja tetrahedral complexes.
Sigma Bonding in Square Planar Complexes
Insure planar complexes, he cas avd. de de bn (an be (5)
yume.
The parbiuishaveaz(p,)onde(pa, Py symensie The fuligandsIying along te x and y=
axes give rie o igan group orbitals af ay, by ang, mme. These LGO interet with metal
cb of ans syn sigma molecular bias as shownin Fig. 426. Th ayy LGO ntrats with
both aig mel orbitals o fon one Bonding ag and one sg antbonding and one antibonding
leur omit. The metal bil dy, € And 07, remain nonhonding because they have no
symmetry sico LOS.
In general, the square planar complexes are formed by d* metal ons like Ni?" (with strong ligands
IGN"), Pd and a?" ons. There are siten valence clon ight om the furligands and ight
from melon ight eloctons from ligands ocupy te bonding tleclarobitas (a, by andes)
and eight electrons fo the el on oca Py, andar (lit antibonding) molecular abia
and becomploxes ae diamagoetc. The que plana conpleacsaebigly stable, though they contain
16 valse lcrns, This i due 1 he resson ht le bonding MOS are fled athe antbonding
MOS ae empty. Adding editioal electra would deuil the complex because the additional
electrons would ets ito the antibonding mocelar bis and lower the bond order. The complexes
containing heros les ha 16 are also less able because they hve Jess numberof electrons in
tending molecular oras ad lower the bond ade.
Fig. 26 Molecule agri, bag jasa pla compen
“Ties fc el Ligand Bondi in Conia
Be
sume nine valence orbital available for bonding ut tee syn properties are different for each
geometry. Fora tetrahedral ML complex, the metal s and poils have ay and f2.symeties
repectvely. The dy dye and dar ovis aver and d'y add riss have espanto, tis
seenthatthe symmetries ofp-rbitlsand hat fd, dy and oil are identical et symnety.
“isd tthe fact that th orbitals iyidzed with bit (Ayo) and dy, d andar
oral hybridized with sofa (hybrid) frm teeabedralgeontery. OF the four Hand
group abials (LG0s) constucted fom ligand loue pair bias one have a and thes have 7
smmeties. The ay orbital LGO interacts with a, esl of meal o give one bonding ard one
antibonding MO and 13 LGOS can interact with bob ses of obialsofmeal (Pand day, d, do
site one bonding and two antibonding molecular bs (Fig, 425). In contas o he ocak
complexes, he meta orbitals re non-boning The separo between thee andthe nex high 2
lecular onal i equal to, as in CFT For a complex sch as (CaC fer ar oa Gen
valen electors of which cigh electron ae produced by four igand (wo electrons per Tigan) and
‘the Ca? (4” ion finishes seven electron. Bight electron ac ld in the banding MOS (a an 1),
four clans in non bonding e obits and tre in he slightly aasbondig > octal.
25 MO itiggram for booting ja tetrahedral complexes.
Sigma Bonding in Square Planar Complexes
Insure planar complexes, he cas avd. de de bn (an be (5)
yume.
The parbiuishaveaz(p,)onde(pa, Py symensie The fuligandsIying along te x and y=
axes give rie o igan group orbitals af ay, by ang, mme. These LGO interet with metal
cb of ans syn sigma molecular bias as shownin Fig. 426. Th ayy LGO ntrats with
both aig mel orbitals o fon one Bonding ag and one sg antbonding and one antibonding
leur omit. The metal bil dy, € And 07, remain nonhonding because they have no
symmetry sico LOS.
In general, the square planar complexes are formed by d* metal ons like Ni?" (with strong ligands
IGN"), Pd and a?" ons. There are siten valence clon ight om the furligands and ight
from melon ight eloctons from ligands ocupy te bonding tleclarobitas (a, by andes)
and eight electrons fo the el on oca Py, andar (lit antibonding) molecular abia
and becomploxes ae diamagoetc. The que plana conpleacsaebigly stable, though they contain
16 valse lcrns, This i due 1 he resson ht le bonding MOS are fled athe antbonding
MOS ae empty. Adding editioal electra would deuil the complex because the additional
electrons would ets ito the antibonding mocelar bis and lower the bond order. The complexes
containing heros les ha 16 are also less able because they hve Jess numberof electrons in
tending molecular oras ad lower the bond ade.
Fig. 26 Molecule agri, bag jasa pla compen
osc ER Cal
Crystal Field Splitting Diagrams for Tigonal bipyramidal, Square pyramidal and
Pentagonal bipyramidal Complexes
Enea
nas
|
Fite in the Boos
1. In CHF, Cel is octahedral surounded by six” Hands with two longer Cr—F bonds and four
shorter ones becuse of.
1¢ [FeX 4), where X is a monodentate ligand, has one unpaired electron. The X” ligand
produce à Hl x
3. CN” isao-donoras wells. . ligand, we
4. Nil isa deer ian. Wears
5. The diposive anstionmels wich ieon he line of hydration energy curve u.
6. [Fe(NH3)6 1" is unstable because NH does not form „with Fe,
7. The algebraic sum of all energy shifts of all orbitals should be.
8. The d-orbitals which participate in dsp" hybridization are.
9. The d-orbitals which participate in sd? hybridization are
10. The orbital with highest neg in out and in distorted otahedal complexes a.
and respecte
11, The highest energy otal in tiga bipyramidal complex is
12, The hybridization in (CUM a a EA
13. According to OFT, tr bond between ell cation and the ligands is
14. Among the [CoNHs 61°", Be(NHs)s)°*.(Fe(bpy)s "+ the A, is highest for...
15. CN” ligand causes song spliting of bits in complexes because itis god.
16. CY” liga causes weak siting of bil in complexes because iis a good
and
17. The geomety of(NiCLe]™ and [PC]? are and respectively
(Ans, 1. Jshn-Feller disorton 2. ston,
3. naccepor ao
zer
5 Mg? anda «6. bond
Las da pda
9. dentada 10 da pde
da 12 pd
13, nie 14, RQ)
15. sacceptor 16. ndoror
17. ttabedra, square planar ]
Crystal Field Splitting Diagrams for Tigonal bipyramidal, Square pyramidal and
Pentagonal bipyramidal Complexes
Enea
nas
|
Fite in the Boos
1. In CHF, Cel is octahedral surounded by six” Hands with two longer Cr—F bonds and four
shorter ones becuse of.
1¢ [FeX 4), where X is a monodentate ligand, has one unpaired electron. The X” ligand
produce à Hl x
3. CN” isao-donoras wells. . ligand, we
4. Nil isa deer ian. Wears
5. The diposive anstionmels wich ieon he line of hydration energy curve u.
6. [Fe(NH3)6 1" is unstable because NH does not form „with Fe,
7. The algebraic sum of all energy shifts of all orbitals should be.
8. The d-orbitals which participate in dsp" hybridization are.
9. The d-orbitals which participate in sd? hybridization are
10. The orbital with highest neg in out and in distorted otahedal complexes a.
and respecte
11, The highest energy otal in tiga bipyramidal complex is
12, The hybridization in (CUM a a EA
13. According to OFT, tr bond between ell cation and the ligands is
14. Among the [CoNHs 61°", Be(NHs)s)°*.(Fe(bpy)s "+ the A, is highest for...
15. CN” ligand causes song spliting of bits in complexes because itis god.
16. CY” liga causes weak siting of bil in complexes because iis a good
and
17. The geomety of(NiCLe]™ and [PC]? are and respectively
(Ans, 1. Jshn-Feller disorton 2. ston,
3. naccepor ao
zer
5 Mg? anda «6. bond
Las da pda
9. dentada 10 da pde
da 12 pd
13, nie 14, RQ)
15. sacceptor 16. ndoror
17. ttabedra, square planar ]
ee 3 5 Carias Chest
Objective Questions
1. The crystal eld stabilization energy (CFSE), in units of for[CoFs (HO) is:
(90 mos
(908 (918
2. FD) de nanas due fod soni et 2 000" Tee
the crystal ci stabilization energy is
(@)-20000em"! ©) Aoc
(e) 80000 (4) -8,000cm
ich ono te folowing octal ompless willbe died?
er >
AS AS
4, The crystal feld pling een (A) for COCHE i 15000 The fora would be
£a) 18000em 16) 16000em =}
(©) 80000" (65 20000m"!
he esta fel satiation energy (CFSE) wil be the highest o
€) Co} (W)CO(ENS)
(Mato oca)
6. Among (CHz)5 P,NO*,CN” and 1 ligands, the one which is not a macceptorligand is:
on A Gen
CLS @ CHP
Se complex wth maximum CFSE is
SS) ta" 6) (Co(t120)5 1"
AÚN (Core
3. The compound which exhibits Jah Tell disertin is
CARS CM OP
ON" CIÈCURS
9. The numberof maganese ions in tetrahedral and ected ie, especie in Mn 304 are
{@) one Ma?" and two Mn?* (9) one Mn and two Mn?"
40) two Mn and one Ma? (6) two Mn?" and one Mn?*
10. The spinels Cafe 0g nd FeO, respectively are
(8) averse and inverse inverse and ronal
(e) normal ad comal (8) moral and inverse
“Tia fo ME ind Banting Compre FU 455
UL Inthe trigonal bipyramidal crystal feld, the orbital with the highest energy i:
@ dey LES
Ody @d?
12. Themagntie moment ofthe complex K 3 {CoM .Oup. Theron stabilization energy willbe:
@) 048, (9)-048, +P
CETTE] (1845438
13. Forte complex ion (ONE 6, the coordination geomet willbe
octet (©) teteagonalty stoned wheal
de) ional psi (6) rigonal antprismati.
14. The complex ion [Ni(CMa]”" has square planar configuartion with magnetic moment of zero.
‘What would te magnetic moment fit were ttahedrl?
(94348M. 6) 1738M.
46) 2878M. (59 BA
15. Arange te folowing metal comple inorder of hic inceasing hydration energy
PO MOS NEO AE
e Q ® ©
WS<P<Q<R @)P<Q<R<S
WQ<P<R<S ()S<R<Q<P a
16. The structure of he complexes [Cu(N Ja CIO) and [ONIS )4JCIOS) ir solution
respectively ar +
(a) square planer ond tabl
Gé ad sur praia Qe a
(6) oca and trigonal bipyremidt eo
(6 cebada und square
17. The constatent abot the
(@ shite nd ame eg
Ce aa bonds ae longer tan he equi ones
19 the equal bods ae longe than he aia ones
¡eN bond distance in Cu(NH Jo is:
nm.
GET ei he es one
iterctons with the meta! d-rbitals in an octahedra geometry is
Ar Ore (0) rg
(e ing 7
do Joso) nai
(a) iy? eZ
oma ads
20. The CESE fr the flowing d® metal ons (V2* Cr?" Mo") decreases the following order:
Objective Questions
1. The crystal eld stabilization energy (CFSE), in units of for[CoFs (HO) is:
(90 mos
(908 (918
2. FD) de nanas due fod soni et 2 000" Tee
the crystal ci stabilization energy is
(@)-20000em"! ©) Aoc
(e) 80000 (4) -8,000cm
ich ono te folowing octal ompless willbe died?
er >
AS AS
4, The crystal feld pling een (A) for COCHE i 15000 The fora would be
£a) 18000em 16) 16000em =}
(©) 80000" (65 20000m"!
he esta fel satiation energy (CFSE) wil be the highest o
€) Co} (W)CO(ENS)
(Mato oca)
6. Among (CHz)5 P,NO*,CN” and 1 ligands, the one which is not a macceptorligand is:
on A Gen
CLS @ CHP
Se complex wth maximum CFSE is
SS) ta" 6) (Co(t120)5 1"
AÚN (Core
3. The compound which exhibits Jah Tell disertin is
CARS CM OP
ON" CIÈCURS
9. The numberof maganese ions in tetrahedral and ected ie, especie in Mn 304 are
{@) one Ma?" and two Mn?* (9) one Mn and two Mn?"
40) two Mn and one Ma? (6) two Mn?" and one Mn?*
10. The spinels Cafe 0g nd FeO, respectively are
(8) averse and inverse inverse and ronal
(e) normal ad comal (8) moral and inverse
“Tia fo ME ind Banting Compre FU 455
UL Inthe trigonal bipyramidal crystal feld, the orbital with the highest energy i:
@ dey LES
Ody @d?
12. Themagntie moment ofthe complex K 3 {CoM .Oup. Theron stabilization energy willbe:
@) 048, (9)-048, +P
CETTE] (1845438
13. Forte complex ion (ONE 6, the coordination geomet willbe
octet (©) teteagonalty stoned wheal
de) ional psi (6) rigonal antprismati.
14. The complex ion [Ni(CMa]”" has square planar configuartion with magnetic moment of zero.
‘What would te magnetic moment fit were ttahedrl?
(94348M. 6) 1738M.
46) 2878M. (59 BA
15. Arange te folowing metal comple inorder of hic inceasing hydration energy
PO MOS NEO AE
e Q ® ©
WS<P<Q<R @)P<Q<R<S
WQ<P<R<S ()S<R<Q<P a
16. The structure of he complexes [Cu(N Ja CIO) and [ONIS )4JCIOS) ir solution
respectively ar +
(a) square planer ond tabl
Gé ad sur praia Qe a
(6) oca and trigonal bipyremidt eo
(6 cebada und square
17. The constatent abot the
(@ shite nd ame eg
Ce aa bonds ae longer tan he equi ones
19 the equal bods ae longe than he aia ones
¡eN bond distance in Cu(NH Jo is:
nm.
GET ei he es one
iterctons with the meta! d-rbitals in an octahedra geometry is
Ar Ore (0) rg
(e ing 7
do Joso) nai
(a) iy? eZ
oma ads
20. The CESE fr the flowing d® metal ons (V2* Cr?" Mo") decreases the following order:
‘SBS RR eae ERO Conan
BAN EFT OO
ea mar 12
GM > Cri > va Cr’ > Mot > va
E. or
(9) Co) (0) CHO)"
H,O)" OFEN
22. Which ofthe following shows NORMAL spinel stare 7
©) Fes04 (0) MazO4
(6) NiAL¿04 (4) Lazu,
©: molecular orbital treatment of (Mn(CO)<}*, ye symmetry of the LGO that is NOT
ia boning, is .
@) Ay OT À
Ole PAS
24. CESE fansiion metal complexes can be deine! by
IÓ lec Y
(©) Micfowave spectroscopy (ONMR spectroscopy
25. Which one ofthe following pars of electronic configuration ohigh-sin transition metal ios (3)
in en octahedral field undergo a substantial Jahn-Teller distin ?
@d da Ha,
ode wd
26. Jahn-Teller distortion of CuSO, SH, Oacts o
(6) raise symmetry
(@)cemave a electronic degeneracy
(© cause loss of iO igand
(@ promote adelectron to an antibonding moleular rita
27. According to crystal field theory, Ni?* can have two unpaired electron in
(a) octahedral geometry only (b) square-planar geometry only”
2, O tic rom ny (octal eal poner
38. Forte complexes
ODER" 6) MAR) (CYCLOP | HALO Pie eal
cetaedal geometry wil nt be observed in: —
O) 000)
© @)only Oy Ll A
29. The enthalpies of hydration ofCa”*, Mn?* and Zn”* follow the order: aoe oe
(0 Ma? > Cas zu? uw." ds A
(0)Za?* >Ca?* > Mn? pa 1 en
() Mn > zu? > ca?
GO Zn > Ma?" > Cat
30. The comet order of acidity among the following species is
[NCH O) 1" > [NH0)6* > [MA(E20)6]* > Seth)"
CLSe(H2O)6}** > ENiCH2O)6}* > [MinlHO)6]°* > NAO)"
(6) [Ma(t,0)6}** > [NI(H20)6]** > [Se(Hiz0)g}** > [NaHz0)6
(BAHR) > {Na(H20)s]" > INILO)6 7" >EMalFzO)¢]*
31. Te comet order of orbital sping in a trgonl bipyramidal goomety is
QE de da poto, (dada da puto B
A Ordi aby > dandy —
32. Asaligad CT is:
(a) only a o-donor (6) only a #donor
(both ac-donor and a donor (d) a0-donor and ao-acceptor
533, Which of fe following complexes has the highest number of wpaied electrons?
(Cy GEO) PT
© HAGANCS)4] GC)
34. Which sie comect statement about the NN bond in{Ni(NHs 6?
(2) Allare of equal bond lengths
(0) The two axial bonds are longer than the four equatorial bonds
(c) The four equatoris! bonds are longer than the two axial bonds
(d) None of the bond length are equal
38, Theabsrvation of equal Cu-O distance in he hex-coordatd Cul) complex,
KPt{CuNO»)g Js best understood in tems of:
(a) Failure of the Jahn-Teller theorem to predict the structure of this complex.
(b) Error in the crystallographic estimate of Cu-O distances
(© Dynamic Jahn-Teller distortion ofthe Cu-O bonds
(0 Symmeial dB de nie alce eros of CA)
6. Wisknown hat pK, of witers 15.7 Badan ti water pK, benchmark, range the following
sobatedmetls-aqua ions in order of hit increasing ci
Mn?" (H20)6, Fe**(H20)6, Cu?” (H20)6, Ca} (H:0)s.
(6) Alla same acides
Fe < Cu? < Mn" < Ca?
Ca eu? Matt < Fe
(aca <a? < Cu Fe",
37. The pir simple and inverse spines respective
(0 Fey0y and Mn304 (0) Fes0, 200304
(© MnO, and Nifez04 (@)NiFe20, and 00504
BAN EFT OO
ea mar 12
GM > Cri > va Cr’ > Mot > va
E. or
(9) Co) (0) CHO)"
H,O)" OFEN
22. Which ofthe following shows NORMAL spinel stare 7
©) Fes04 (0) MazO4
(6) NiAL¿04 (4) Lazu,
©: molecular orbital treatment of (Mn(CO)<}*, ye symmetry of the LGO that is NOT
ia boning, is .
@) Ay OT À
Ole PAS
24. CESE fansiion metal complexes can be deine! by
IÓ lec Y
(©) Micfowave spectroscopy (ONMR spectroscopy
25. Which one ofthe following pars of electronic configuration ohigh-sin transition metal ios (3)
in en octahedral field undergo a substantial Jahn-Teller distin ?
@d da Ha,
ode wd
26. Jahn-Teller distortion of CuSO, SH, Oacts o
(6) raise symmetry
(@)cemave a electronic degeneracy
(© cause loss of iO igand
(@ promote adelectron to an antibonding moleular rita
27. According to crystal field theory, Ni?* can have two unpaired electron in
(a) octahedral geometry only (b) square-planar geometry only”
2, O tic rom ny (octal eal poner
38. Forte complexes
ODER" 6) MAR) (CYCLOP | HALO Pie eal
cetaedal geometry wil nt be observed in: —
O) 000)
© @)only Oy Ll A
29. The enthalpies of hydration ofCa”*, Mn?* and Zn”* follow the order: aoe oe
(0 Ma? > Cas zu? uw." ds A
(0)Za?* >Ca?* > Mn? pa 1 en
() Mn > zu? > ca?
GO Zn > Ma?" > Cat
30. The comet order of acidity among the following species is
[NCH O) 1" > [NH0)6* > [MA(E20)6]* > Seth)"
CLSe(H2O)6}** > ENiCH2O)6}* > [MinlHO)6]°* > NAO)"
(6) [Ma(t,0)6}** > [NI(H20)6]** > [Se(Hiz0)g}** > [NaHz0)6
(BAHR) > {Na(H20)s]" > INILO)6 7" >EMalFzO)¢]*
31. Te comet order of orbital sping in a trgonl bipyramidal goomety is
QE de da poto, (dada da puto B
A Ordi aby > dandy —
32. Asaligad CT is:
(a) only a o-donor (6) only a #donor
(both ac-donor and a donor (d) a0-donor and ao-acceptor
533, Which of fe following complexes has the highest number of wpaied electrons?
(Cy GEO) PT
© HAGANCS)4] GC)
34. Which sie comect statement about the NN bond in{Ni(NHs 6?
(2) Allare of equal bond lengths
(0) The two axial bonds are longer than the four equatorial bonds
(c) The four equatoris! bonds are longer than the two axial bonds
(d) None of the bond length are equal
38, Theabsrvation of equal Cu-O distance in he hex-coordatd Cul) complex,
KPt{CuNO»)g Js best understood in tems of:
(a) Failure of the Jahn-Teller theorem to predict the structure of this complex.
(b) Error in the crystallographic estimate of Cu-O distances
(© Dynamic Jahn-Teller distortion ofthe Cu-O bonds
(0 Symmeial dB de nie alce eros of CA)
6. Wisknown hat pK, of witers 15.7 Badan ti water pK, benchmark, range the following
sobatedmetls-aqua ions in order of hit increasing ci
Mn?" (H20)6, Fe**(H20)6, Cu?” (H20)6, Ca} (H:0)s.
(6) Alla same acides
Fe < Cu? < Mn" < Ca?
Ca eu? Matt < Fe
(aca <a? < Cu Fe",
37. The pir simple and inverse spines respective
(0 Fey0y and Mn304 (0) Fes0, 200304
(© MnO, and Nifez04 (@)NiFe20, and 00504
eee
noti Fin sem ms by son eevee is de
ent) aan TO
ano patenting (eat) sano
30. Viet 0 OE
Ten aran
nen oa
a) ning toco ep)
OCASO sen OC NO A,
(Jen < NO3 <CsH5N< Phen — (d) CsHsN <NOz <en< Phen >
41. Ta the solid ste tte CuCl ion av pes of bonds. These ae
(a) three long and two short à (b) two long and three short
o Neem |
Dar ong aye eae Hp:
CaF, NBts, CO and CoHy =
(a) CO<C2Fy <CaHe<NEts WC <CaHly € NE <CO xv
© Ca Ha < NEts <CO<CoEa (ONEIS <C2¥lg< CaF, <CO
43, The comet spinel structure o£Co3O4 is: A
(0) Co"), £C0**),04 EG?) (co*'Co),04
O0 AR (Co”*) 04
10 10 10 40 SO 60 10
20 FRE MO LOG 2H 2H WO
BQ 6 TH RH BMH BH HO
29 20 20 BH BH MA BO
BO BO BO BO BH MO BO
MO MO 20) BO BH LG 20
aa 5
jective Questions |
1 Pe ion forms octahedral whereas Pt* forms square plana complexes, Explain,
2. PAI) makes square planar complexes almost exclusively. Explain withthe help of crystal field
theory.
3. What isthe effect of donor and acceptor lgands on Ag? Explain on the basis of ligand field
theory.
4. Crystal field splitting energy A» for (CH NH3)5]?" is 10,200 cm”! while for (Cr(NH pe
5,900 cm”. Explain.
5. Draw the crystal field splining diagram for (Cola and caleulate CFSE,
6, Determine the CFSE of a d° complex having 10 Dq = 25,000 cm“! and P = 15,000cm™ (rm
pairing energy).
7. Which complex in each ofthe falling ais wit have pester crystal fldspiting and why?
(a) (Cofends P* or [Rh]
(ICHEN} Po (CNE)
OFEN" or (RECN) 6 >
(@){Fe(H2O)g}°* or [FANS
(©)[ColNO2)¢}*" orfCofONO)6]*~
8. Tetrahedral complexes are high spin. Explain.
3. Explain the variation of latice energies ofthe divalent 34 series transition metal halides,
10. KN] is diamagnetic wile K [Co] is parmagnetc. Both have same deonfigutin.
spin on he bass of CFT,
1, Fora complex ion [Mal], where is newal mono-dentate ligand, the mean pring eng]
(P)is found to be 28,000 em"! ifthe magninude of A, is 21,000 cm”, calculate CFSE.
12. Ks(CHNCS)5) has a magnetic moment of 5.0 B.M while K {C(CN)¢] has a value of only 3.2
"BM. Give the geometry ofeach complex onthe basis of VET.
13. Defin Jahn-Teller theo. Gin gras, expinin which case hs effect would e observed?
DATI]
PE
14. On he basis of VB, account fr he magnetic properties of
ONE DEP" (DECO De fü) (FCN. GF) CHL} ET CON)
15, Inthe crystal ofCuF Cu?" ion is surounded by six” with four Fat a distance-of 193 pam vb.
to F at 227 po. Explain
16. Fortetakedeal complexes, =
e Explaa
17. The magnetic moment of[MaBes]”” and [Ma(CN)5]”" are 5.9 and 2.9 B.M. respectively. Using
VOT, asign the geometries of dese complexes,
18. Cobalt) is easily oxidized to cobalt) inthe presence of strong field lands but the isoelectronic
nickel) complexes are oxidizing agent. Explain on the basis of CFT.
noti Fin sem ms by son eevee is de
ent) aan TO
ano patenting (eat) sano
30. Viet 0 OE
Ten aran
nen oa
a) ning toco ep)
OCASO sen OC NO A,
(Jen < NO3 <CsH5N< Phen — (d) CsHsN <NOz <en< Phen >
41. Ta the solid ste tte CuCl ion av pes of bonds. These ae
(a) three long and two short à (b) two long and three short
o Neem |
Dar ong aye eae Hp:
CaF, NBts, CO and CoHy =
(a) CO<C2Fy <CaHe<NEts WC <CaHly € NE <CO xv
© Ca Ha < NEts <CO<CoEa (ONEIS <C2¥lg< CaF, <CO
43, The comet spinel structure o£Co3O4 is: A
(0) Co"), £C0**),04 EG?) (co*'Co),04
O0 AR (Co”*) 04
10 10 10 40 SO 60 10
20 FRE MO LOG 2H 2H WO
BQ 6 TH RH BMH BH HO
29 20 20 BH BH MA BO
BO BO BO BO BH MO BO
MO MO 20) BO BH LG 20
aa 5
jective Questions |
1 Pe ion forms octahedral whereas Pt* forms square plana complexes, Explain,
2. PAI) makes square planar complexes almost exclusively. Explain withthe help of crystal field
theory.
3. What isthe effect of donor and acceptor lgands on Ag? Explain on the basis of ligand field
theory.
4. Crystal field splitting energy A» for (CH NH3)5]?" is 10,200 cm”! while for (Cr(NH pe
5,900 cm”. Explain.
5. Draw the crystal field splining diagram for (Cola and caleulate CFSE,
6, Determine the CFSE of a d° complex having 10 Dq = 25,000 cm“! and P = 15,000cm™ (rm
pairing energy).
7. Which complex in each ofthe falling ais wit have pester crystal fldspiting and why?
(a) (Cofends P* or [Rh]
(ICHEN} Po (CNE)
OFEN" or (RECN) 6 >
(@){Fe(H2O)g}°* or [FANS
(©)[ColNO2)¢}*" orfCofONO)6]*~
8. Tetrahedral complexes are high spin. Explain.
3. Explain the variation of latice energies ofthe divalent 34 series transition metal halides,
10. KN] is diamagnetic wile K [Co] is parmagnetc. Both have same deonfigutin.
spin on he bass of CFT,
1, Fora complex ion [Mal], where is newal mono-dentate ligand, the mean pring eng]
(P)is found to be 28,000 em"! ifthe magninude of A, is 21,000 cm”, calculate CFSE.
12. Ks(CHNCS)5) has a magnetic moment of 5.0 B.M while K {C(CN)¢] has a value of only 3.2
"BM. Give the geometry ofeach complex onthe basis of VET.
13. Defin Jahn-Teller theo. Gin gras, expinin which case hs effect would e observed?
DATI]
PE
14. On he basis of VB, account fr he magnetic properties of
ONE DEP" (DECO De fü) (FCN. GF) CHL} ET CON)
15, Inthe crystal ofCuF Cu?" ion is surounded by six” with four Fat a distance-of 193 pam vb.
to F at 227 po. Explain
16. Fortetakedeal complexes, =
e Explaa
17. The magnetic moment of[MaBes]”” and [Ma(CN)5]”" are 5.9 and 2.9 B.M. respectively. Using
VOT, asign the geometries of dese complexes,
18. Cobalt) is easily oxidized to cobalt) inthe presence of strong field lands but the isoelectronic
nickel) complexes are oxidizing agent. Explain on the basis of CFT.
TE ES FE A.
id coin Crh on andy sic nina celta gery athe OE
"acne Do tent ying cred geome MF aot
nl a rec pl
20.1” isa wean as” icon Explain on he as of LT
21, dnd Sei etn dene ki pn compres Bin
22, The enthalpy of hydration ofCr?* is -460 kcal mot" In the presence of CFSE, the value of AH
‘would be 435 kcal mol”. Estimate the valve of 4 , for [Cr(H20)5)”*.
23. The magnetic moment offFe(H20)¢]** was found to be 5.9 BM. and of[Fe(CN)]* is 19B.M.
ccoo de dove brain bis VE,
24. The [NKCN)4J ion is square planar and diamagnetic whereas [NICL,]2 is tetrahedral and
e Expl
28, We mon abi: ic mein aus aa, ar pi
26, Weak ligands form High spin complexes whereas strong ligands form low spin complexes with
Bd ransion metal ons. Explain
27. Square planar geomet is especially common for d°.configuration. Explain
aaa
Electromagnetic radiations of whit light (sch as sun light) consist of a continuous spectrum of
wavelengths or wave numbers conespnding o diferent colours. Ifa compound abs ight (photon)
of one coos, (sy orange). ten ites (or transmits) Tigh of bl colour Thetarsnited (or
reflctod) light of lu color atacks onthe retina of ou eyes and the compound is sen lo be bee
coloured. The colour oftrasmitd igh is called complementary color of absorbed light A compound
appears blue it absoebsradadons oF al colours but reflects blue color Le, i absorbs radiations of
‘white igh minas blue colour. A compound le looks blue if it reflects all colours except range the
<ommplementaryclourof thie. A compound appears black it absorbsall he ration ofthe tga
visible region. Y a conn absorbs o vibe fight, it appews white or coudes. Moat le
transition metal complexes show variety of colours that depend on the nature of metal and the ligands.
For example, Ii(H20)6P à purple, (COI¿O)6 "is pink, [Cu (H)O)e isis, (Cr(Hs0)e JF
is violet [Cr(130)6]'* is blue [CoClA]?” is blue, (NI(H0)6]?* is green, Ni (NH IG] is ble,
Lien) à is violet Wien ammoni is added to {NE (HO), he green colour is hanged ine
due to the formation of [NI(NH3)g]"*. When ethylenediamine is added to Ni) or
(Ni) ?* ‚green and blue colours change to violet due to the formation. of (Nien) +.
Using an ati! colour wher Figure 51, can be determined the observed colour of «compound
front the colour of absorbed light. Complementary colours are shown on opposite sides of te colour
wheel, The colours of absorbed and reflected light are complimentary to eachother
== 7 ÓN
id coin Crh on andy sic nina celta gery athe OE
"acne Do tent ying cred geome MF aot
nl a rec pl
20.1” isa wean as” icon Explain on he as of LT
21, dnd Sei etn dene ki pn compres Bin
22, The enthalpy of hydration ofCr?* is -460 kcal mot" In the presence of CFSE, the value of AH
‘would be 435 kcal mol”. Estimate the valve of 4 , for [Cr(H20)5)”*.
23. The magnetic moment offFe(H20)¢]** was found to be 5.9 BM. and of[Fe(CN)]* is 19B.M.
ccoo de dove brain bis VE,
24. The [NKCN)4J ion is square planar and diamagnetic whereas [NICL,]2 is tetrahedral and
e Expl
28, We mon abi: ic mein aus aa, ar pi
26, Weak ligands form High spin complexes whereas strong ligands form low spin complexes with
Bd ransion metal ons. Explain
27. Square planar geomet is especially common for d°.configuration. Explain
aaa
Electromagnetic radiations of whit light (sch as sun light) consist of a continuous spectrum of
wavelengths or wave numbers conespnding o diferent colours. Ifa compound abs ight (photon)
of one coos, (sy orange). ten ites (or transmits) Tigh of bl colour Thetarsnited (or
reflctod) light of lu color atacks onthe retina of ou eyes and the compound is sen lo be bee
coloured. The colour oftrasmitd igh is called complementary color of absorbed light A compound
appears blue it absoebsradadons oF al colours but reflects blue color Le, i absorbs radiations of
‘white igh minas blue colour. A compound le looks blue if it reflects all colours except range the
<ommplementaryclourof thie. A compound appears black it absorbsall he ration ofthe tga
visible region. Y a conn absorbs o vibe fight, it appews white or coudes. Moat le
transition metal complexes show variety of colours that depend on the nature of metal and the ligands.
For example, Ii(H20)6P à purple, (COI¿O)6 "is pink, [Cu (H)O)e isis, (Cr(Hs0)e JF
is violet [Cr(130)6]'* is blue [CoClA]?” is blue, (NI(H0)6]?* is green, Ni (NH IG] is ble,
Lien) à is violet Wien ammoni is added to {NE (HO), he green colour is hanged ine
due to the formation of [NI(NH3)g]"*. When ethylenediamine is added to Ni) or
(Ni) ?* ‚green and blue colours change to violet due to the formation. of (Nien) +.
Using an ati! colour wher Figure 51, can be determined the observed colour of «compound
front the colour of absorbed light. Complementary colours are shown on opposite sides of te colour
wheel, The colours of absorbed and reflected light are complimentary to eachother
== 7 ÓN
F
52 SEA Corbis Genis.
nd anne gon an ogni
cnica
see ie rn capt une
Fre crete anna eee
ad
men ee nee
E ected ae
he ight ao)
E —— Grune te
PS
If the clectromagoetc radiations absorbed by a compound lie in UV or IR region, then the
‘ranted (oe refered) light wl icin UV or IR region andthe compound appears colorless.
“Phe energy of absorbe light depends on the spacing between ground and excited sates. The enorgy
of separation between two sates is given by
(= velocity oflight = 10° ems“!
A wavelength of light absorbed (em)
fequencyof light absorbed (=!)
= wave mur (en) =!
Insome complexes th vali ery small nd these abri dits inf gion and
tis appear olores beans infrared radiations are colours
Wide sane way, some complexes a age A value large every ie been ground ste
and exi sate) and absorb ight radiations in UV region nd thes apper alu.
The magnitud of erst fel split (A) can e measured with th el ol wavelength of light
arte The meat lc amount fig absorbe by a compound sai bre (og
nd aplotof baoiance versus wavelength or wave number, Sellen sbsoonspectum. The est
cramgle forte measurement of magnitude of A is (HO) Because Ton has only one
isn in 34 orbialand gives oly one peak in its clctoni spectrum Th color offi (HO) 1°"
ions pape. This complexion te eletron occupies the orita of te Lost enr e any one of
‘the degenerate, orbitals. The purple colour OP(Ti(H20)6]”" fon is due t absorption of blue-green
tight and ain of electron o e fg obits to one of he degenerate rl. Te absorption
ne
Chandler peta 33 ree
spectrum of [T(Hj0), * reveals that the did transition occurs with a single broad peak with a
maximum absorption at 20300 cm’ (wavelength of 498 ama) which corresponds to 243 kJ mol" energy
{Figure 5.3).
Since 1 mal = 83.7 em!
Ts à eI (0) 2000 sr
‘Thea! case is one ofthe simplest case because energy of bsorbed light is equal tothe magnitude of
Ay, for other d* electronic configuration, the electron-electron interactions must be taken into account
and oe altos ae involved for determination of 4, vale
ann Ga
eo
Wave umber er") 2
Pass
Most ofthe complexes of transition lement give broad absorption bands extending over several
thousand wave mumbes. In ansia meal complexes the MCL bonds ar not sd. When ht is
sorbed ran mea complex electronic transitions and vibrations occur simutancousty which
‘recalled vibronic transitions, Due to vibrations of ligands energy of d-electrons changes. When a ligand
moves towards the nstion metal the value o A, increases and when a ligand moves away fom the
osiion metal energy of electrons increases. According to Frank Concon principe", during one
vibro, arg numbers electronic tansiions over several thousand wave mumbers oe. The two
ena factors which are responsible for broad bands are spot coupling and Jahn-Teller
distortion
‘Sharp pesks ee observed in complexes where A, doesnot change o energy of ground state and
exc state changes ely. Sharp peaks are observed for high spin Me? complexes.
Fax Codon spe ts cta tacon re much fase aw stoi tios.
wey
bf
wo
52 SEA Corbis Genis.
nd anne gon an ogni
cnica
see ie rn capt une
Fre crete anna eee
ad
men ee nee
E ected ae
he ight ao)
E —— Grune te
PS
If the clectromagoetc radiations absorbed by a compound lie in UV or IR region, then the
‘ranted (oe refered) light wl icin UV or IR region andthe compound appears colorless.
“Phe energy of absorbe light depends on the spacing between ground and excited sates. The enorgy
of separation between two sates is given by
(= velocity oflight = 10° ems“!
A wavelength of light absorbed (em)
fequencyof light absorbed (=!)
= wave mur (en) =!
Insome complexes th vali ery small nd these abri dits inf gion and
tis appear olores beans infrared radiations are colours
Wide sane way, some complexes a age A value large every ie been ground ste
and exi sate) and absorb ight radiations in UV region nd thes apper alu.
The magnitud of erst fel split (A) can e measured with th el ol wavelength of light
arte The meat lc amount fig absorbe by a compound sai bre (og
nd aplotof baoiance versus wavelength or wave number, Sellen sbsoonspectum. The est
cramgle forte measurement of magnitude of A is (HO) Because Ton has only one
isn in 34 orbialand gives oly one peak in its clctoni spectrum Th color offi (HO) 1°"
ions pape. This complexion te eletron occupies the orita of te Lost enr e any one of
‘the degenerate, orbitals. The purple colour OP(Ti(H20)6]”" fon is due t absorption of blue-green
tight and ain of electron o e fg obits to one of he degenerate rl. Te absorption
ne
Chandler peta 33 ree
spectrum of [T(Hj0), * reveals that the did transition occurs with a single broad peak with a
maximum absorption at 20300 cm’ (wavelength of 498 ama) which corresponds to 243 kJ mol" energy
{Figure 5.3).
Since 1 mal = 83.7 em!
Ts à eI (0) 2000 sr
‘Thea! case is one ofthe simplest case because energy of bsorbed light is equal tothe magnitude of
Ay, for other d* electronic configuration, the electron-electron interactions must be taken into account
and oe altos ae involved for determination of 4, vale
ann Ga
eo
Wave umber er") 2
Pass
Most ofthe complexes of transition lement give broad absorption bands extending over several
thousand wave mumbes. In ansia meal complexes the MCL bonds ar not sd. When ht is
sorbed ran mea complex electronic transitions and vibrations occur simutancousty which
‘recalled vibronic transitions, Due to vibrations of ligands energy of d-electrons changes. When a ligand
moves towards the nstion metal the value o A, increases and when a ligand moves away fom the
osiion metal energy of electrons increases. According to Frank Concon principe", during one
vibro, arg numbers electronic tansiions over several thousand wave mumbers oe. The two
ena factors which are responsible for broad bands are spot coupling and Jahn-Teller
distortion
‘Sharp pesks ee observed in complexes where A, doesnot change o energy of ground state and
exc state changes ely. Sharp peaks are observed for high spin Me? complexes.
Fax Codon spe ts cta tacon re much fase aw stoi tios.
wey
bf
wo
SS
«ofthe lanthanoïd complexes sharp bands ae observed in absorption spectra. The Jia
In M9 ep and here is no interaction of ligands with f-otbitls. Any vibration of ligands or change
ried Ponds does not change the energy offlectons and magie of will emain unaffected
poate
Table 5.1 Colours of Absorbed Light and Complementary Colours
SES
Colourless(UV) | Cotouñess
[4000 ‚oo _ | 22000-25000 Violet Yellow
[ons | 20000-22000 | Bine Orange
mom Ionen Red
en | 17000-18000 | Yellow Violet
pose 15000-17000 Orange Blue
Red Green
_L Cotouriessinftared) | Gotourtess
[ten soo
Lambert Law
y
"ightofintensity 1, ofa given wave number (Vor wavekngihpassesthrougha solution the
is wit intensity F which lower than th intensity ofthe incident light (o).
o Beer-Lamber las, absorbance ofthe solution is given by:
le
fo
Aus
pasota
here molar absorptivity or molar absorption coefficient (moi em)
{= at nat (en)
= eoncentration of solution (moi 1)
Sr isa dimensionless quant.
Baar versus wavelength of wave number 8 called absorption spectrum
y
THE ANGULAR MOMENTUM OF AN ELECTRON.
opie #2" Momentum
2
‚moving ints orbital round he cles posees an angular moment which called
And clar momentum. A measure of ob angler momentum () is given by / tales
cob ft te orbit
Orbital angular momentem (1) = rH A
¡ii angular momentum quantum uber
63% 10% Is
mentum vector quan
qi
‘Angular momentum is a vector quant
Lis always 260 or positive value and hence so L
Ter moe vector (provides +) cents in pce aout any give reference
Aiton eel vera xi) in uch mana at is compere slong te econ din
aint mips tan shown ie Sr =2 Theconponsntt inten dicción
doren s Sino ae integral malls of, he components an be representdin terms af
am integal number LL is the magnetic quantum number, y.
Foret,
Forl=2, 2
la general, One CDE
Te orbital corresponding to 21+ 1 values are degenerate because energy ofan electron depends
‘only ou the magnitude but not on the direcion of anguiar momentum,
2. Electron Spin Angular Momentum
„Aalen into sat Gal moving abou the mc bal spiming about it own axis-The
“ping motion of én electro generates an angular moment, called as spa angular moment (o)
ich sala vor quanti
Spinanguar momentum (5) = SGD. À
Nbre
4 2 sin quantum number
‘The spin angular momgntym (s) provides (2s-+1) two orienations shout the
reference direction ( Le. z-axis) in such a manner that its components along the
reference direction are half integral multiples off /2a(FigureS5). The component ots
log the reference direction an be represented in terms of 5, arm, The values of
1
are+lor-1
harley
«ofthe lanthanoïd complexes sharp bands ae observed in absorption spectra. The Jia
In M9 ep and here is no interaction of ligands with f-otbitls. Any vibration of ligands or change
ried Ponds does not change the energy offlectons and magie of will emain unaffected
poate
Table 5.1 Colours of Absorbed Light and Complementary Colours
SES
Colourless(UV) | Cotouñess
[4000 ‚oo _ | 22000-25000 Violet Yellow
[ons | 20000-22000 | Bine Orange
mom Ionen Red
en | 17000-18000 | Yellow Violet
pose 15000-17000 Orange Blue
Red Green
_L Cotouriessinftared) | Gotourtess
[ten soo
Lambert Law
y
"ightofintensity 1, ofa given wave number (Vor wavekngihpassesthrougha solution the
is wit intensity F which lower than th intensity ofthe incident light (o).
o Beer-Lamber las, absorbance ofthe solution is given by:
le
fo
Aus
pasota
here molar absorptivity or molar absorption coefficient (moi em)
{= at nat (en)
= eoncentration of solution (moi 1)
Sr isa dimensionless quant.
Baar versus wavelength of wave number 8 called absorption spectrum
y
THE ANGULAR MOMENTUM OF AN ELECTRON.
opie #2" Momentum
2
‚moving ints orbital round he cles posees an angular moment which called
And clar momentum. A measure of ob angler momentum () is given by / tales
cob ft te orbit
Orbital angular momentem (1) = rH A
¡ii angular momentum quantum uber
63% 10% Is
mentum vector quan
qi
‘Angular momentum is a vector quant
Lis always 260 or positive value and hence so L
Ter moe vector (provides +) cents in pce aout any give reference
Aiton eel vera xi) in uch mana at is compere slong te econ din
aint mips tan shown ie Sr =2 Theconponsntt inten dicción
doren s Sino ae integral malls of, he components an be representdin terms af
am integal number LL is the magnetic quantum number, y.
Foret,
Forl=2, 2
la general, One CDE
Te orbital corresponding to 21+ 1 values are degenerate because energy ofan electron depends
‘only ou the magnitude but not on the direcion of anguiar momentum,
2. Electron Spin Angular Momentum
„Aalen into sat Gal moving abou the mc bal spiming about it own axis-The
“ping motion of én electro generates an angular moment, called as spa angular moment (o)
ich sala vor quanti
Spinanguar momentum (5) = SGD. À
Nbre
4 2 sin quantum number
‘The spin angular momgntym (s) provides (2s-+1) two orienations shout the
reference direction ( Le. z-axis) in such a manner that its components along the
reference direction are half integral multiples off /2a(FigureS5). The component ots
log the reference direction an be represented in terms of 5, arm, The values of
1
are+lor-1
harley
TE Cana Chis
3. Spin-Orbit Coupling
‘The interaction of orbital angular momentum with spin angular momentum is called spin-orbit
coupling, The strength of coupling and its effect on energy levis ofthe atomuspend on te orientativas
Gforbital and spin angular momenta,
4. Total Angular Momentum
At is the vector sum of orbita! angular momentum and spn angular momentum. When the octal
“angular momentum and spin angular momentum ae pale, he total angular momentum is high and
‘ene the to angular moments are opposite to one sober, the total angular moment is low.
Total angular momenturs ()
13 en to ange mamen rate)
3 =1 Lowen so angular moments ati ops eos)
{nother words, we can say hat jis halfitegl, ine sis half integral for one electron atom.
jean also be expressed in tems of total angular momentum quantum number (j
IAE
THE TOTAL ANGULAR MOMENTUM OF MANY
lia aria ELECTRONS ATOMS.
4. The Total Orbital Angular Momentum
‘When 0 or more electrons are present in a subshel of an atom, their individual orbital angular
momenta may add together orappose each ober. The total obit angular momentum (1) given by.
Hi.
wat
where
Ls total orbital angular momentum quantum number (a non-negative integer)
After are two elecrons in a subi with otal angular moment quan numbes A and
respectively Th valu of is oa by coupling he divide orbital angular momentum quanta,
‘ambers by using he Clebsch-Gonis sis
Lol bh th ll =
Sine Lis nonnegative, so modas siga suso. So odia! angular momenta ate pal, then
eh + Ris maximum evo orbital angular een ae opposed then = — a!) is iim,
‘he internat values represent posible imite lave oretaons ofthe wo moment. For
dectons = h =2
L= 2422424, PH
24,3,2,1,0
For the quantum numbers L=0, ,2,3....hetemsS,P,0,F,
areused which reparto
«perales or s,p, df... obits,
fori= 0 1 3 4 5 6 1
Tem 8 Pp D 6 6 & 1 «
Oral angelar moment has 2 + tatin disgusto by he quantum number
My AL LW, nun o
A closed shell has zero orbital anguiac momentum because the sum of individual orbital angular
moment is zero,
2.The Total Spin Angular Momentum
When two or more electrons até present ia subchelofan atom. The total spin angular moment
(is given dy
s 507.2
where
‘$= total spin angular momentum quantum number
Sis le non-negative integer ot zero only ifnumber of electrons is even 0e half integer if umber
ofelectons is odd.
The values of Scan be obtained by using the Clebsch Goran seis. there are ono econ with
pin quantum numbers 5, andy Den
A]
‘Modulus sign is used because Sisa non-negative integer or hal integer.
Foccch lona |
5-1, (ecto em)
sak, Mot ro often (soi
BA oan are (ion)
‘The pin multiplicity of tenn i828 +1 E LE
2. Spin-Orbit Coupling
[there are two or more electrons in gabi, there is coupling of al the spins and all he orbital
angular momenta. There are two diffrent ways in which the coupling of spin and orbital angular
‘momenta take place.
GLS Coupling or Russel Saunders Coupling
LS coupling occus in toms of ow toni numbers becuse in hese ators spin-orbit coupling is
weak First sum the oil angular momentunto give ou Land then spin angular momenta given
Iota separately and finally add hese two moment to give the total angular mementum (J)
isch $
3. Spin-Orbit Coupling
‘The interaction of orbital angular momentum with spin angular momentum is called spin-orbit
coupling, The strength of coupling and its effect on energy levis ofthe atomuspend on te orientativas
Gforbital and spin angular momenta,
4. Total Angular Momentum
At is the vector sum of orbita! angular momentum and spn angular momentum. When the octal
“angular momentum and spin angular momentum ae pale, he total angular momentum is high and
‘ene the to angular moments are opposite to one sober, the total angular moment is low.
Total angular momenturs ()
13 en to ange mamen rate)
3 =1 Lowen so angular moments ati ops eos)
{nother words, we can say hat jis halfitegl, ine sis half integral for one electron atom.
jean also be expressed in tems of total angular momentum quantum number (j
IAE
THE TOTAL ANGULAR MOMENTUM OF MANY
lia aria ELECTRONS ATOMS.
4. The Total Orbital Angular Momentum
‘When 0 or more electrons are present in a subshel of an atom, their individual orbital angular
momenta may add together orappose each ober. The total obit angular momentum (1) given by.
Hi.
wat
where
Ls total orbital angular momentum quantum number (a non-negative integer)
After are two elecrons in a subi with otal angular moment quan numbes A and
respectively Th valu of is oa by coupling he divide orbital angular momentum quanta,
‘ambers by using he Clebsch-Gonis sis
Lol bh th ll =
Sine Lis nonnegative, so modas siga suso. So odia! angular momenta ate pal, then
eh + Ris maximum evo orbital angular een ae opposed then = — a!) is iim,
‘he internat values represent posible imite lave oretaons ofthe wo moment. For
dectons = h =2
L= 2422424, PH
24,3,2,1,0
For the quantum numbers L=0, ,2,3....hetemsS,P,0,F,
areused which reparto
«perales or s,p, df... obits,
fori= 0 1 3 4 5 6 1
Tem 8 Pp D 6 6 & 1 «
Oral angelar moment has 2 + tatin disgusto by he quantum number
My AL LW, nun o
A closed shell has zero orbital anguiac momentum because the sum of individual orbital angular
moment is zero,
2.The Total Spin Angular Momentum
When two or more electrons até present ia subchelofan atom. The total spin angular moment
(is given dy
s 507.2
where
‘$= total spin angular momentum quantum number
Sis le non-negative integer ot zero only ifnumber of electrons is even 0e half integer if umber
ofelectons is odd.
The values of Scan be obtained by using the Clebsch Goran seis. there are ono econ with
pin quantum numbers 5, andy Den
A]
‘Modulus sign is used because Sisa non-negative integer or hal integer.
Foccch lona |
5-1, (ecto em)
sak, Mot ro often (soi
BA oan are (ion)
‘The pin multiplicity of tenn i828 +1 E LE
2. Spin-Orbit Coupling
[there are two or more electrons in gabi, there is coupling of al the spins and all he orbital
angular momenta. There are two diffrent ways in which the coupling of spin and orbital angular
‘momenta take place.
GLS Coupling or Russel Saunders Coupling
LS coupling occus in toms of ow toni numbers becuse in hese ators spin-orbit coupling is
weak First sum the oil angular momentunto give ou Land then spin angular momenta given
Iota separately and finally add hese two moment to give the total angular mementum (J)
isch $
and UE
were
toral angule momentum guantum number (Non negative integer or half itege)
‘The permitted values of can be obtained by using Clebsch ~ Gordan serios
JALAS,L+S=k 11281
IE tec is a single electron outside closed shell hen.
and is cher + Lort- 1
ister + hort}.
6 jf Coupling
Frjeouplingoccus in heavy oma whee ept-rbit coupling sr. the spin and ttl angular
moments of each election are coupled together strongly, then it may be considered that each election
Echoes sa particle
Fs sun the oil and spin moment of esc electron separately and then sum to indivi
mere pesa
| and Jolie
| erste gsi toscas oe
ticrosttes
Ti leon configuro ofan alam, on or moles is ot compl design of
amet flans inanıbshelofen am. For ven leon conga, areas
ways of arrangement of eletons ina subshell. For example, for p?-electronie configuration, ee are
15 ways in which elections can be atranged. Similarly for d?-configuration, there áre 45 ways of
| rangement of electrons, The different ways in which the electrons can be arranged in the obials of a
teams Benge, Mois ao alo aos
Number ofmierosates = N!
where
N #2 +2) twice the number of orbitals,
x= number folios
6
For example mierosutes for p?-configuation= 5
> 26-51
srta
PA
=15
1
2 >
a o
«TE ou
sta li | — o
sl 1 oo.
E 1 oo
8 b o +
s 1 o +
w #4
" #4 0
2 “4
a an
“ 4 0
s 4 4
‘Spectroscopic Terms : Ifthe inter electronic repulsions are very small. negligible thea the
microstates ofa given electronic configuration have the same energy. But atoms and molecules are
‘compact, therefore, the inte electronic repulsions are really Strong and can not be ignored. As a
resul, microsttes which corespond to different relative spatial arrangement of electrons have
difieren energies. Ifthe mierosttes that have the same energy are grouped together when
{nfer-electronic repulsions are taken into account, the spectroscopicalty different energy levels are
‘obtained and these energy levels ae called terms or atomie states. These tems ae characterized by
symbols Sand L, Thus,
“The values of correspond to atomic states described a6 S, P, DF... which are parle to the
values of Ffors,p, dy Fn. obitals,
‘The atomic sates or terms ae very important in the interpretation of spectra of coordination
compounds,
Term Symbols; The term symbol fora particular atomic state or tera is writen as
25+1
L
J
Ground State Term : Hund's Rule
“The terms derived for an lectoni configuration have different energies. For example, te p
electronic configuration gives rise othretenasitat are 3, Ip ands. These thee terms have diferent
————————
were
toral angule momentum guantum number (Non negative integer or half itege)
‘The permitted values of can be obtained by using Clebsch ~ Gordan serios
JALAS,L+S=k 11281
IE tec is a single electron outside closed shell hen.
and is cher + Lort- 1
ister + hort}.
6 jf Coupling
Frjeouplingoccus in heavy oma whee ept-rbit coupling sr. the spin and ttl angular
moments of each election are coupled together strongly, then it may be considered that each election
Echoes sa particle
Fs sun the oil and spin moment of esc electron separately and then sum to indivi
mere pesa
| and Jolie
| erste gsi toscas oe
ticrosttes
Ti leon configuro ofan alam, on or moles is ot compl design of
amet flans inanıbshelofen am. For ven leon conga, areas
ways of arrangement of eletons ina subshell. For example, for p?-electronie configuration, ee are
15 ways in which elections can be atranged. Similarly for d?-configuration, there áre 45 ways of
| rangement of electrons, The different ways in which the electrons can be arranged in the obials of a
teams Benge, Mois ao alo aos
Number ofmierosates = N!
where
N #2 +2) twice the number of orbitals,
x= number folios
6
For example mierosutes for p?-configuation= 5
> 26-51
srta
PA
=15
1
2 >
a o
«TE ou
sta li | — o
sl 1 oo.
E 1 oo
8 b o +
s 1 o +
w #4
" #4 0
2 “4
a an
“ 4 0
s 4 4
‘Spectroscopic Terms : Ifthe inter electronic repulsions are very small. negligible thea the
microstates ofa given electronic configuration have the same energy. But atoms and molecules are
‘compact, therefore, the inte electronic repulsions are really Strong and can not be ignored. As a
resul, microsttes which corespond to different relative spatial arrangement of electrons have
difieren energies. Ifthe mierosttes that have the same energy are grouped together when
{nfer-electronic repulsions are taken into account, the spectroscopicalty different energy levels are
‘obtained and these energy levels ae called terms or atomie states. These tems ae characterized by
symbols Sand L, Thus,
“The values of correspond to atomic states described a6 S, P, DF... which are parle to the
values of Ffors,p, dy Fn. obitals,
‘The atomic sates or terms ae very important in the interpretation of spectra of coordination
compounds,
Term Symbols; The term symbol fora particular atomic state or tera is writen as
25+1
L
J
Ground State Term : Hund's Rule
“The terms derived for an lectoni configuration have different energies. For example, te p
electronic configuration gives rise othretenasitat are 3, Ip ands. These thee terms have diferent
————————
ee
energies. These terms represent three states with different amount oPinterelecrone repulsons. The
ground state tm (lowest energy can be determined by using the Hund’ rls.
1. Fora given configuration, the ground sate term (term of lowest energy) i tht which has highest
sin mukipliiy. The ground state, thecefore, have the highest numberof unpaired eletrons and
this gives seo minimum repulsion and high exchange energy. Forexample, the ground sat term
for p?-coafiguration is 3p.
2, Hthetvo states have the sme spin muliplicity, the state with highest value of wi be the ground
state. For example, for d? configuration, the tens ae3p,3p, 1g, Ip andlg.3 and 3p both
have same spin multiplicity but 3 has higher value of Z. Thus, 3p has lower energy then 3p
Hence 3e isthe ground state,
3. Fora given electronic configuration if spin multplicites are same andthe values of are also same
fortwo atom stats, (hen the state having lowest value wil b of lowest nergy ifthe subse is
Jess thao half led, and the state having highest value ofJ willbe oflowestenergythesubshell is
more than half filled.
‘he subshell is exactly half fle, thas oy one value of J. This law is applicable when spin-orbit
couplings taken into account.
To Identify the Ground State Term and Ground State Term Symbol for Atoms
Following steps are used to identify the ground state:
(0 dei the mieronute that has the highest value ofS.
(0) Find out the spin multiplicity (25 + 1)
(@)Detecmine the maxima possible value of M (= Em )ord.
(4) Select maximum valve of for more than half filled subshell nd rinimum value of for less
han half illedsubshel,
Examples:
© p?-Contguration :
m #10 -1
Spin multliciy=29+1=2> 141
Ground state term =3p
TALS, u [LS]
Since psubsbel is ess tao hat filled,
2 Ground state tena symbol = >,
L=M¿=+1+0-1=0, Sato
3
Helle
asetaasdeind
Cran sr em
For LA -
toad 53
+2] -;
baldes]
-”
+ Ground state term symbol = “Sy
(Gi) For 4? Configuration (Ti? or Y?" ion)
my HO 12 My=241=3, Foto
TTT
sel
ee
2sele2<141
Ground state tena = 3p
JelltSb....\E-51
then. Bell
=432
Since Graba is less han half filed, lowest value of J will give the ground state term. Therefore,
ground state term symbol = °F. The 4" and a9" configutions give identical terms (Table 52)
‘Table 5.2: Terms for d” Configurations
ind Sites | OE eam
Tero :
2» =
e Brass
4p 4p2p2odedodn
So Spdodedo3u-
Isitosteslody
é 6s 4.40.48 46.25.27,
Een
a is =
energies. These terms represent three states with different amount oPinterelecrone repulsons. The
ground state tm (lowest energy can be determined by using the Hund’ rls.
1. Fora given configuration, the ground sate term (term of lowest energy) i tht which has highest
sin mukipliiy. The ground state, thecefore, have the highest numberof unpaired eletrons and
this gives seo minimum repulsion and high exchange energy. Forexample, the ground sat term
for p?-coafiguration is 3p.
2, Hthetvo states have the sme spin muliplicity, the state with highest value of wi be the ground
state. For example, for d? configuration, the tens ae3p,3p, 1g, Ip andlg.3 and 3p both
have same spin multiplicity but 3 has higher value of Z. Thus, 3p has lower energy then 3p
Hence 3e isthe ground state,
3. Fora given electronic configuration if spin multplicites are same andthe values of are also same
fortwo atom stats, (hen the state having lowest value wil b of lowest nergy ifthe subse is
Jess thao half led, and the state having highest value ofJ willbe oflowestenergythesubshell is
more than half filled.
‘he subshell is exactly half fle, thas oy one value of J. This law is applicable when spin-orbit
couplings taken into account.
To Identify the Ground State Term and Ground State Term Symbol for Atoms
Following steps are used to identify the ground state:
(0 dei the mieronute that has the highest value ofS.
(0) Find out the spin multiplicity (25 + 1)
(@)Detecmine the maxima possible value of M (= Em )ord.
(4) Select maximum valve of for more than half filled subshell nd rinimum value of for less
han half illedsubshel,
Examples:
© p?-Contguration :
m #10 -1
Spin multliciy=29+1=2> 141
Ground state term =3p
TALS, u [LS]
Since psubsbel is ess tao hat filled,
2 Ground state tena symbol = >,
L=M¿=+1+0-1=0, Sato
3
Helle
asetaasdeind
Cran sr em
For LA -
toad 53
+2] -;
baldes]
-”
+ Ground state term symbol = “Sy
(Gi) For 4? Configuration (Ti? or Y?" ion)
my HO 12 My=241=3, Foto
TTT
sel
ee
2sele2<141
Ground state tena = 3p
JelltSb....\E-51
then. Bell
=432
Since Graba is less han half filed, lowest value of J will give the ground state term. Therefore,
ground state term symbol = °F. The 4" and a9" configutions give identical terms (Table 52)
‘Table 5.2: Terms for d” Configurations
ind Sites | OE eam
Tero :
2» =
e Brass
4p 4p2p2odedodn
So Spdodedo3u-
Isitosteslody
é 6s 4.40.48 46.25.27,
Een
a is =
Terms in ground state and excited state with same mutplicty are important for discusion of
P-Octahedral Syrametry +
con spectra. Gr) d?-Octahedrat Symmetry
‘To identity the Ground State Term in Octahedral Complexes
(0) Sketch te energy eves (zz and ey showing the deso with maximum value of M,
det spin utility.
(©) Determine the maximum possible value of My or.
> iy
ON |
240
Mp= 2414023, : Fsae
‘Examples : sl
P 3
High spin a: 2
i warerxditas
43 2
2 Ground state term = 4
iia SELECTION RULES.
rn Intensities of Absorption Bands of Complexes : The electronic transitions between d-orbitalsce,
atinada Anoeta! amples ot In era comparant When ded
2 ‘transitions occur in complexes with centres of syınmetry such as regular octzhedeal complexes, the
2=0, 2. Ssate intense ofabsorpion bands reos BT esd taro occurin complexes which nck cars
+. Ground state term = 85 of symmetry such as tetrahedral complexes and octahedral cis-complexes of the type MA4 Ba, relatively
CO Loin à un absorption bands ar observed. Fr example en on, CI added to an aqueous solution of
T Co (D, the colour changes from pink of {Co(H0)«)"* to intenso blue colour of CoC
== Theron in the elive tenses o absorption bands cante explained y a sere of selection
ns.
111]
LOU (1) Laporte Selection Rule pet
Mpe2e2414140%6, dae The tanstns that ocur between stes of oposite py Lg. war allowed. means hat
sol LL, . 10p pordandd ef vanstonsare alone
1735222
‘The transitions that occur between states of same pati Le, g <> g ocu <> ware forbidden.
For example, d-d transitions are forbidden because dati are gerade, Ze. these have centre of
symmetry with respect o wave function. 3
Laporte selection rule may also be given as follows, The transitions ia which change in azimuthal
quantum numbers is +1 £., AZ =i, are Laporte allowed and absorbance may be high. If AL =0, the
trastions are Laporte forbidden and, therefore, absorbance is iw.
ass tean Leioa sae
Ground state tern
ii) High spin 4 1
> Relaxation in Laporto's Selection Rule
Thed-diranstions are Laporte forbidden and however have much lower absorbance in the range of
10:50 mot emi because there is ligt relaxation in th Laporte” selection rule. The meta ligands
à Same bonds in tramition metal complexes are not rigid. When UV-visible fight is incident on a complex,
clectoie transitions as well as vibrations occur simultaneously. In octahedral complexes the ligand
braten sucha way that centre of symmetry is temporarily destroyed and there is a very small mixing of
28+1m2x 34127 ‘eed obits amd hs dd transitions are not purely Lapore forbidden but here is slight relaxation in
Ground state term = 78 aportes ul. Therefore, the octahedral complexes show colar of low intensity
P-Octahedral Syrametry +
con spectra. Gr) d?-Octahedrat Symmetry
‘To identity the Ground State Term in Octahedral Complexes
(0) Sketch te energy eves (zz and ey showing the deso with maximum value of M,
det spin utility.
(©) Determine the maximum possible value of My or.
> iy
ON |
240
Mp= 2414023, : Fsae
‘Examples : sl
P 3
High spin a: 2
i warerxditas
43 2
2 Ground state term = 4
iia SELECTION RULES.
rn Intensities of Absorption Bands of Complexes : The electronic transitions between d-orbitalsce,
atinada Anoeta! amples ot In era comparant When ded
2 ‘transitions occur in complexes with centres of syınmetry such as regular octzhedeal complexes, the
2=0, 2. Ssate intense ofabsorpion bands reos BT esd taro occurin complexes which nck cars
+. Ground state term = 85 of symmetry such as tetrahedral complexes and octahedral cis-complexes of the type MA4 Ba, relatively
CO Loin à un absorption bands ar observed. Fr example en on, CI added to an aqueous solution of
T Co (D, the colour changes from pink of {Co(H0)«)"* to intenso blue colour of CoC
== Theron in the elive tenses o absorption bands cante explained y a sere of selection
ns.
111]
LOU (1) Laporte Selection Rule pet
Mpe2e2414140%6, dae The tanstns that ocur between stes of oposite py Lg. war allowed. means hat
sol LL, . 10p pordandd ef vanstonsare alone
1735222
‘The transitions that occur between states of same pati Le, g <> g ocu <> ware forbidden.
For example, d-d transitions are forbidden because dati are gerade, Ze. these have centre of
symmetry with respect o wave function. 3
Laporte selection rule may also be given as follows, The transitions ia which change in azimuthal
quantum numbers is +1 £., AZ =i, are Laporte allowed and absorbance may be high. If AL =0, the
trastions are Laporte forbidden and, therefore, absorbance is iw.
ass tean Leioa sae
Ground state tern
ii) High spin 4 1
> Relaxation in Laporto's Selection Rule
Thed-diranstions are Laporte forbidden and however have much lower absorbance in the range of
10:50 mot emi because there is ligt relaxation in th Laporte” selection rule. The meta ligands
à Same bonds in tramition metal complexes are not rigid. When UV-visible fight is incident on a complex,
clectoie transitions as well as vibrations occur simultaneously. In octahedral complexes the ligand
braten sucha way that centre of symmetry is temporarily destroyed and there is a very small mixing of
28+1m2x 34127 ‘eed obits amd hs dd transitions are not purely Lapore forbidden but here is slight relaxation in
Ground state term = 78 aportes ul. Therefore, the octahedral complexes show colar of low intensity
id Ete Seid EAE Se? E EA
In tetrahedral complexes there is no centre of symmetry and p-d mixing is more pronounced in
tetrahedral complexes because 3 molecular orbitals are formed fom omic d (gerade) and p (ungerade)
orbitals. Tevahedral completes, therefor, absorb more strongly than octahedral complexes. Therefore,
the tetrahedral complexes give more intense colour tan octahedral complexes.
(2) Spin Selection Rule
‘Transitions between stes fame mull ar slowed,
Le. AS =0, spin allowed
In other word, during electronic aston spin ofthe electro is nt changed, tente transition
isspinallowel.
“Transitions between stes fire muliplicis ae spin forbidden.
Le, AS 20, spin forbidden
For example : For configuration in an ctbedeal field, there are four states with same
spin multiplicity o 3 (5 = 1) one of whichis ground stats 37 Jan the other three are excited
Hates, (hg, Sag and 37 (PI. Thos there are hree transitions which ae spin allowed. These
are:
Mag Mi
Saag EST ei
EIN DETM
The transition rom ig 1 any ee exi ats ae sin forbidden
Relaxation fn Spin Selection Rule
Spin-orbi coupling can relax the spin scale wide result at transitions mayb observed
ftom ground ste of one spin muliliciy to excited state of different spin rultipicity. These
are generally much weaker han spi allowed transitions. The stengt of
and, therfore, the absorption bands ae weak witha molar absorptivity about 1 Lol ‘em. Spir-obit
coupling in 44 and Sd trans metal complexes is rong, absomtion bands, herefe, ar sronger ie,
intensities ofthese complexes ar greater tha or metal complexes. +
A Laporte forbidden ded transition is moe intense dan a spin forbidden transition.
Table5.3: Molar Absorbance for Various Electronio Transitions
(Spin Selection af | Molar Absarbance nr ann
nun EEN he
Allowed Allowed 10108 07, GO,
007, CIF
Party allowed | Allowed da | 10240? [CoC {CoB}
‘ome pd mixing)
Forbidden Allowed dd [810 EL O) F* INH )g e
y
Party allowed | Forbidden [ad [23
some pd mixing
Forbidden Forbidden [ad |o102 Aro)
(acta? (Mee
Splitting of Terms in Octahedral and Tetrahedral Complexes
“The wave function for, P,D, Fn. aes have same syrmetny asthe wave funcions for he
comesponding eof , pd... ital.
‘An s-abitl is spherically symmtcal and paris le on axes. There i no effet of octahedral or
tetahedral field on orbitals te, ner energy of sabia is increased nor spliting ofan soil
oscars. Since State has same emery st of abil, so theres also no effet of ctahedral and
Aexahedral Slds on S sate.
Since al the p-rbitals ion axe, other is no splitng of p-orbitls in octahedral and tetrahedral
Fils but energy of -orital ese equally state bs same syrmetey a ha of portals Theres
no spliting of P state butts energy sabed as dt of portals
A set of bits is split in 10g and ey (in taeda cd) or e and 13 (im terabodal Geh).
‘Therefore, a D term is pitino Tg and Ey (m ocahedrl field) or B and T> (in teuahedrl ick.
‘Similarly, F term is split int thee tems Tig, Tag and Ayg (in octahedral field) oT), T and Ay
(a tetahedral ld)
In an oetahed
field, splining of D and sites are shown in Figure 5.6 and 57.
In tetrahedral complexes there is no centre of symmetry and p-d mixing is more pronounced in
tetrahedral complexes because 3 molecular orbitals are formed fom omic d (gerade) and p (ungerade)
orbitals. Tevahedral completes, therefor, absorb more strongly than octahedral complexes. Therefore,
the tetrahedral complexes give more intense colour tan octahedral complexes.
(2) Spin Selection Rule
‘Transitions between stes fame mull ar slowed,
Le. AS =0, spin allowed
In other word, during electronic aston spin ofthe electro is nt changed, tente transition
isspinallowel.
“Transitions between stes fire muliplicis ae spin forbidden.
Le, AS 20, spin forbidden
For example : For configuration in an ctbedeal field, there are four states with same
spin multiplicity o 3 (5 = 1) one of whichis ground stats 37 Jan the other three are excited
Hates, (hg, Sag and 37 (PI. Thos there are hree transitions which ae spin allowed. These
are:
Mag Mi
Saag EST ei
EIN DETM
The transition rom ig 1 any ee exi ats ae sin forbidden
Relaxation fn Spin Selection Rule
Spin-orbi coupling can relax the spin scale wide result at transitions mayb observed
ftom ground ste of one spin muliliciy to excited state of different spin rultipicity. These
are generally much weaker han spi allowed transitions. The stengt of
and, therfore, the absorption bands ae weak witha molar absorptivity about 1 Lol ‘em. Spir-obit
coupling in 44 and Sd trans metal complexes is rong, absomtion bands, herefe, ar sronger ie,
intensities ofthese complexes ar greater tha or metal complexes. +
A Laporte forbidden ded transition is moe intense dan a spin forbidden transition.
Table5.3: Molar Absorbance for Various Electronio Transitions
(Spin Selection af | Molar Absarbance nr ann
nun EEN he
Allowed Allowed 10108 07, GO,
007, CIF
Party allowed | Allowed da | 10240? [CoC {CoB}
‘ome pd mixing)
Forbidden Allowed dd [810 EL O) F* INH )g e
y
Party allowed | Forbidden [ad [23
some pd mixing
Forbidden Forbidden [ad |o102 Aro)
(acta? (Mee
Splitting of Terms in Octahedral and Tetrahedral Complexes
“The wave function for, P,D, Fn. aes have same syrmetny asthe wave funcions for he
comesponding eof , pd... ital.
‘An s-abitl is spherically symmtcal and paris le on axes. There i no effet of octahedral or
tetahedral field on orbitals te, ner energy of sabia is increased nor spliting ofan soil
oscars. Since State has same emery st of abil, so theres also no effet of ctahedral and
Aexahedral Slds on S sate.
Since al the p-rbitals ion axe, other is no splitng of p-orbitls in octahedral and tetrahedral
Fils but energy of -orital ese equally state bs same syrmetey a ha of portals Theres
no spliting of P state butts energy sabed as dt of portals
A set of bits is split in 10g and ey (in taeda cd) or e and 13 (im terabodal Geh).
‘Therefore, a D term is pitino Tg and Ey (m ocahedrl field) or B and T> (in teuahedrl ick.
‘Similarly, F term is split int thee tems Tig, Tag and Ayg (in octahedral field) oT), T and Ay
(a tetahedral ld)
In an oetahed
field, splining of D and sites are shown in Figure 5.6 and 57.
a EEE
s 4e A
DB Ty ñ
» Bts Ree
£ | +h +4
G | Ag ty the tT MESA,
# DEREN Em
INTERPRETATION OF ELECTRONC SPECTRA OF HIGH SPIN OCTAHEDRAL AND
TETRAHEDRAL COMPLEXES (ORGEL DIAGRAMS)
‘Orgs ingrums re pastel seal in the interpretation of spin allowed eletonietastons of
tezahedrl ara igh spin octabedal complexes but rot fr low spin octaheral complexes. The spin
allowed electron transitions ocur betwen the two energy sales (ie, terms) that have same pin
tipi The energy ference Between ground state and any ofthe exited sate ie ger as RP
fc» Boltzmmunconsantand =abrlste temperature) almost the molecules of complexcopomd
re present in ci ground ste Therefore, helctoni transitions occ for grosa teo excited
ats. In some complexes (like high sia Mn?” octahedal complexes) spin forbidden tension also
cur but he nent fé is weaker (ration in sin selection rule due 1 spi-ait coupling)
[han the spin allowed rnstios. An org iagrar fra given metal on shows the change 6: of
Individual tems wih change and fet strength, As the magnitude of igen Fed stength ners
excite sates with fret symmetry and same spin multiplicity may cos one another
Orgel dingrums can also be used forall octahedra complexes of d',d?,d3,d¥and 4? metal
fstenath oigends (Le, either he ligand s weak or strong) because weak or ong
me ons gives soto identical energy states,
pectra of d? Metal fons in Octahedral Field
Te fee meal ne of configuro, er i o nelson and a ie vo
orbital are degenerate an, therfore, as only one term ie, 2D, Under the inäuense of an
cher ed eiherthe inde weskorsong he obit pino ag and soon
grt of siting, A depends gon e un fins Since wre incon of Diemis
ar 0 at fab, eee, Demis tino 273 and “E, tensa och comple.
€ ground state tm 6273, which is sitas o fg bias having nc cin ad E mis
lar to e obitals haviig no électron which is the excited state. The energy gap between 273, and
ts vis ie a of iets, Wee te ganó lower wi eh nr ap eect
ag and ? E, states and stronger the gd, higher will be energy gap Between 273, and Ey states.
electron always occupies the ground state term, When light is incident on the octahedral complex of
configuration, helen gesencid rom 27, o 2 sateasshown in Figure 54. Tess oy
one electronic transition represented as 7Ey +-? Tag. As the strength of ligand increases, energy of
transition neretses. Por example, tations occur at 13000 cm’, 18900 en“, 2300 en and 22300
eam in CI, [e], TH3OJET* end THCN) 6)” respectively decase eng finds
inerenses according 10 pecto chanical is as CU < F" < Rz0<CN
N» SRE
Ma
Ugand bala sirengin +"
en
‘The absorption bandinthespctaofTTÜH20)]°* is broad because of Jahn TOU distortion, This
Sahn-Veer distortion splits the 22, sate into ? Aug and 724g. This distortion also causes small
spliting of ground state (73, nto *Ey and * Bag [Figure 59
é
me
a
PA
ncomplexion(Ti(H1¿0)6]"" absorption maximum observed at 20300 enr and also he absorption
maximum has a shoulder at 17400 em because of Jahn-Teiler distortion. This shoulder is responsible
for brond bed in the specrum a shown in Figure 5.3
It has also been suggested tha the electronic excited state of[Ti(H20)6} has the configuration
12, eb ado ce ofthecomple rit are elecworzlly degenerate Terre the
single electronic transition i relly he superposition of two transitions, ane rom an octahedral (Ob)
ground sete ion to an octahedral excited sale jon and a lower energy transition fiom an otahedral
{ground state ion toa lower energy ttrgonally distorted excited slate ion (Da. Since these two
s 4e A
DB Ty ñ
» Bts Ree
£ | +h +4
G | Ag ty the tT MESA,
# DEREN Em
INTERPRETATION OF ELECTRONC SPECTRA OF HIGH SPIN OCTAHEDRAL AND
TETRAHEDRAL COMPLEXES (ORGEL DIAGRAMS)
‘Orgs ingrums re pastel seal in the interpretation of spin allowed eletonietastons of
tezahedrl ara igh spin octabedal complexes but rot fr low spin octaheral complexes. The spin
allowed electron transitions ocur betwen the two energy sales (ie, terms) that have same pin
tipi The energy ference Between ground state and any ofthe exited sate ie ger as RP
fc» Boltzmmunconsantand =abrlste temperature) almost the molecules of complexcopomd
re present in ci ground ste Therefore, helctoni transitions occ for grosa teo excited
ats. In some complexes (like high sia Mn?” octahedal complexes) spin forbidden tension also
cur but he nent fé is weaker (ration in sin selection rule due 1 spi-ait coupling)
[han the spin allowed rnstios. An org iagrar fra given metal on shows the change 6: of
Individual tems wih change and fet strength, As the magnitude of igen Fed stength ners
excite sates with fret symmetry and same spin multiplicity may cos one another
Orgel dingrums can also be used forall octahedra complexes of d',d?,d3,d¥and 4? metal
fstenath oigends (Le, either he ligand s weak or strong) because weak or ong
me ons gives soto identical energy states,
pectra of d? Metal fons in Octahedral Field
Te fee meal ne of configuro, er i o nelson and a ie vo
orbital are degenerate an, therfore, as only one term ie, 2D, Under the inäuense of an
cher ed eiherthe inde weskorsong he obit pino ag and soon
grt of siting, A depends gon e un fins Since wre incon of Diemis
ar 0 at fab, eee, Demis tino 273 and “E, tensa och comple.
€ ground state tm 6273, which is sitas o fg bias having nc cin ad E mis
lar to e obitals haviig no électron which is the excited state. The energy gap between 273, and
ts vis ie a of iets, Wee te ganó lower wi eh nr ap eect
ag and ? E, states and stronger the gd, higher will be energy gap Between 273, and Ey states.
electron always occupies the ground state term, When light is incident on the octahedral complex of
configuration, helen gesencid rom 27, o 2 sateasshown in Figure 54. Tess oy
one electronic transition represented as 7Ey +-? Tag. As the strength of ligand increases, energy of
transition neretses. Por example, tations occur at 13000 cm’, 18900 en“, 2300 en and 22300
eam in CI, [e], TH3OJET* end THCN) 6)” respectively decase eng finds
inerenses according 10 pecto chanical is as CU < F" < Rz0<CN
N» SRE
Ma
Ugand bala sirengin +"
en
‘The absorption bandinthespctaofTTÜH20)]°* is broad because of Jahn TOU distortion, This
Sahn-Veer distortion splits the 22, sate into ? Aug and 724g. This distortion also causes small
spliting of ground state (73, nto *Ey and * Bag [Figure 59
é
me
a
PA
ncomplexion(Ti(H1¿0)6]"" absorption maximum observed at 20300 enr and also he absorption
maximum has a shoulder at 17400 em because of Jahn-Teiler distortion. This shoulder is responsible
for brond bed in the specrum a shown in Figure 5.3
It has also been suggested tha the electronic excited state of[Ti(H20)6} has the configuration
12, eb ado ce ofthecomple rit are elecworzlly degenerate Terre the
single electronic transition i relly he superposition of two transitions, ane rom an octahedral (Ob)
ground sete ion to an octahedral excited sale jon and a lower energy transition fiom an otahedral
{ground state ion toa lower energy ttrgonally distorted excited slate ion (Da. Since these two
DELE PAS SP Chi
sonsitions have slghly different energies, therefore, the bands overap one another and can not be
resolved.
"Ths the unresolved superimposed band results in an asymmeti and broad bond. Te splitting of
gst is shown in Figure 5.90)
le,
Top
gan aid sen
RESTE
Spectra of d' Metal ion in Tetrahedral Complexes
The tell complenes ar avays high pin complexes, The Ore dig, heer, can be
asd © nee cir peta, Te trahedral complexes show moe itense absorbance fan thse of
dr complexes because of some pad mixing. Duet some pd ming he sone anions
Vta! be pur deditos, In tebahedral complexes the dignerate do pl ito e and sets
‘Testis. The als ae of lower in energy and 3 orale are of higher in entry, The single
‘con wll ccapy the any o he two e orbital. On absorption of light ection ets excited fom a
titel to one ofthe fp orbitals. Transition of electron is spin allowed. The term foc metal ion of a
configuration is 2D and it splits into À and 27, sates. PE is of tower energy and *7 is of higher
energy. Therefore, electron transition occurs from ? E to 21 as shown in Figure 5.10. The energy leve!
diagram ford! tetrahedral complex isthe inverse of d! octahedral complex.
Tiereis only one elecronie transition from 2 10 273 represented as 273 €? E.
‘Since there is only one transition therefore, only one absorption band is observed in electronic
um +
Spectra of a?-Octahedral Complexes
{noche complexes of d?-metal ins, doris split and ey ata. On atsorpionof
talon gets enced foray toa ey ott. The ound ste temof eed? met ions 2D
which split into 273, and "Estates in octahedral complex io an octahedral complex the electronic
cic eh e). The eg orbitals are doubly degenerate er to electronic
ara ‘ or 8, dl, , a2, ands the espion 2
name de y d'ou aly di andtas he esi
Ina d* octahedral complex a hole may be considered in ey orbitals. When transition occurs, the
dis confturaonbesomes, e an now here vit ag ia This ole the
Ing els may be place in any of the thee ways di, ala ef od dl di of or
di, di, di of, therefore, the mer n is triply degenerate and the term corresponding, to this
pudo ag. Thus the energy of ?E, is lower and that of Fog is higher. In other words, * E
states ground state and 273, is excited state, Since there is hole in *y sate, therefore, there isa hole
trantioa from TE, to PT, which is similar to electron transition and can be represented as
Pag Ey. This is opposite of the order of energies ofthe orbits (1 lower than eg) as shown
Figures.
Je
Lx ii,
ai
fe
He Sion ocean RSR ER
‘The single electronic transition in d' octahedral complex is ZE «Tag and tat for the a
octahedral complex is "Tag «7p. These two cases of d! and a! = dar inversely related. In
general, oc high spin of and dl" high complexes ar inversely related.
sonsitions have slghly different energies, therefore, the bands overap one another and can not be
resolved.
"Ths the unresolved superimposed band results in an asymmeti and broad bond. Te splitting of
gst is shown in Figure 5.90)
le,
Top
gan aid sen
RESTE
Spectra of d' Metal ion in Tetrahedral Complexes
The tell complenes ar avays high pin complexes, The Ore dig, heer, can be
asd © nee cir peta, Te trahedral complexes show moe itense absorbance fan thse of
dr complexes because of some pad mixing. Duet some pd ming he sone anions
Vta! be pur deditos, In tebahedral complexes the dignerate do pl ito e and sets
‘Testis. The als ae of lower in energy and 3 orale are of higher in entry, The single
‘con wll ccapy the any o he two e orbital. On absorption of light ection ets excited fom a
titel to one ofthe fp orbitals. Transition of electron is spin allowed. The term foc metal ion of a
configuration is 2D and it splits into À and 27, sates. PE is of tower energy and *7 is of higher
energy. Therefore, electron transition occurs from ? E to 21 as shown in Figure 5.10. The energy leve!
diagram ford! tetrahedral complex isthe inverse of d! octahedral complex.
Tiereis only one elecronie transition from 2 10 273 represented as 273 €? E.
‘Since there is only one transition therefore, only one absorption band is observed in electronic
um +
Spectra of a?-Octahedral Complexes
{noche complexes of d?-metal ins, doris split and ey ata. On atsorpionof
talon gets enced foray toa ey ott. The ound ste temof eed? met ions 2D
which split into 273, and "Estates in octahedral complex io an octahedral complex the electronic
cic eh e). The eg orbitals are doubly degenerate er to electronic
ara ‘ or 8, dl, , a2, ands the espion 2
name de y d'ou aly di andtas he esi
Ina d* octahedral complex a hole may be considered in ey orbitals. When transition occurs, the
dis confturaonbesomes, e an now here vit ag ia This ole the
Ing els may be place in any of the thee ways di, ala ef od dl di of or
di, di, di of, therefore, the mer n is triply degenerate and the term corresponding, to this
pudo ag. Thus the energy of ?E, is lower and that of Fog is higher. In other words, * E
states ground state and 273, is excited state, Since there is hole in *y sate, therefore, there isa hole
trantioa from TE, to PT, which is similar to electron transition and can be represented as
Pag Ey. This is opposite of the order of energies ofthe orbits (1 lower than eg) as shown
Figures.
Je
Lx ii,
ai
fe
He Sion ocean RSR ER
‘The single electronic transition in d' octahedral complex is ZE «Tag and tat for the a
octahedral complex is "Tag «7p. These two cases of d! and a! = dar inversely related. In
general, oc high spin of and dl" high complexes ar inversely related.
Cosi Che!
{ase ET
“The Orgel diagram for a d°octahedre complex is aralogous tothe d tetrahedral complex. In
general, the Orgel dingam fora” high spin otahedrl complexes is analogous to 49%. tetrahedsal
complex and vice-versa
‘The absorption band of(CutH20)e complex in electronic spectra is observed as broad band
cause ofthe Jahn-Teller distortion.
Explanation of Broad Band in Electronic Spectra of d°-Octahedral Complexes
‘The [CuH30)6?" complex absor in the visible region at 12000 en and this comple is blue
oioured.
Forad?-octahedral complex, th ground state is 2 andiheexcitdste is "Tag. We expectihat
exciation ofa hole occurs from 2 Eto 2Figand a single absron band is observed. But due to
iahn-Teller distortion, 78g state splits into Bi (ower energy and Aig (higher energy) and "Tog
sate splits into Bag (lower energy) and Ey (higher energy) of as shown in Figure 5.13. Now electron
cin mayoeri tom By (vow pros te Ay, Bore, des, This, toe bard
nay be observed, Butsince due to Jahn-Teller distoion spliingof ZE, and “Tye sates is poor, o the
ee absorption bands overlap together showing a road bandas shown in e Figure 5.14.
Aig Bic
Electronic spectra of CuSO 4 -5H¿0
Cu$04 SHO is blue coloured compound and shows an absorption band at ~12000 em
‘The sue of CuSOq SH Os shown in he Fue S15,
‘The anal stretare of CuSO, SHO shaw tat
cach Cu mom is coordinated o four JO and (xo $0, 080
¿son in mans postions andthe BHO molecule a
motboundte Cu dice butt formsbyécogentondswith à
wo S04 groups on neighbouring Cu atoms and two
hydrogen bonds with cis-Hz0 molecules bound to ane of “ON [Na
the Cu atoms. Therefore, in CuSO-SHZO there is N.
ecb exviaument rind the O22" ion, Te 107 | NO
Sore bine sean qc s aiped » 050, \y
ray CE, and it is similar to (Ca(ta0)6)” proa
complexion
‘Now itis observed that one of the HO moleculsis bound more strongly than the other four. These
four water molecules can be removed by warning or over PyOjg. The fi HO molecule can be
removed by heating the compound above 350°C.
04 MO CO — Hom 804 NO
ES, cus, 010 +503
Electronic Spectra of d° Tetrahedral Complexes
Intetrahedral complexes of d? metal ions oia split into fof bigher
bia Figure 5.16). But the spliting is reverse of octahedral complexes. The ground state term of
fee metal cation is ”D . In tetrahedral complexes 2D state splits into 77 and *E states as shown in
Figure 5.17, But energy of these states is also reverse of the d*- octahedral complexes. Thus, in a
tetrahedral complex energy of 273 is lower and thatof *£ishigher. Hole transition oceurs from “73 to
14 e of lower energy
2 state resulting in one absorption band.
Listo noted after sone ormoretolesin ad! oben complex, the ter wil alsabe
same aumber of holes ina tetrahedral complex. The numberof holes in any state oa complex will
never be moe than the number of electrons 0 be excited
{ase ET
“The Orgel diagram for a d°octahedre complex is aralogous tothe d tetrahedral complex. In
general, the Orgel dingam fora” high spin otahedrl complexes is analogous to 49%. tetrahedsal
complex and vice-versa
‘The absorption band of(CutH20)e complex in electronic spectra is observed as broad band
cause ofthe Jahn-Teller distortion.
Explanation of Broad Band in Electronic Spectra of d°-Octahedral Complexes
‘The [CuH30)6?" complex absor in the visible region at 12000 en and this comple is blue
oioured.
Forad?-octahedral complex, th ground state is 2 andiheexcitdste is "Tag. We expectihat
exciation ofa hole occurs from 2 Eto 2Figand a single absron band is observed. But due to
iahn-Teller distortion, 78g state splits into Bi (ower energy and Aig (higher energy) and "Tog
sate splits into Bag (lower energy) and Ey (higher energy) of as shown in Figure 5.13. Now electron
cin mayoeri tom By (vow pros te Ay, Bore, des, This, toe bard
nay be observed, Butsince due to Jahn-Teller distoion spliingof ZE, and “Tye sates is poor, o the
ee absorption bands overlap together showing a road bandas shown in e Figure 5.14.
Aig Bic
Electronic spectra of CuSO 4 -5H¿0
Cu$04 SHO is blue coloured compound and shows an absorption band at ~12000 em
‘The sue of CuSOq SH Os shown in he Fue S15,
‘The anal stretare of CuSO, SHO shaw tat
cach Cu mom is coordinated o four JO and (xo $0, 080
¿son in mans postions andthe BHO molecule a
motboundte Cu dice butt formsbyécogentondswith à
wo S04 groups on neighbouring Cu atoms and two
hydrogen bonds with cis-Hz0 molecules bound to ane of “ON [Na
the Cu atoms. Therefore, in CuSO-SHZO there is N.
ecb exviaument rind the O22" ion, Te 107 | NO
Sore bine sean qc s aiped » 050, \y
ray CE, and it is similar to (Ca(ta0)6)” proa
complexion
‘Now itis observed that one of the HO moleculsis bound more strongly than the other four. These
four water molecules can be removed by warning or over PyOjg. The fi HO molecule can be
removed by heating the compound above 350°C.
04 MO CO — Hom 804 NO
ES, cus, 010 +503
Electronic Spectra of d° Tetrahedral Complexes
Intetrahedral complexes of d? metal ions oia split into fof bigher
bia Figure 5.16). But the spliting is reverse of octahedral complexes. The ground state term of
fee metal cation is ”D . In tetrahedral complexes 2D state splits into 77 and *E states as shown in
Figure 5.17, But energy of these states is also reverse of the d*- octahedral complexes. Thus, in a
tetrahedral complex energy of 273 is lower and thatof *£ishigher. Hole transition oceurs from “73 to
14 e of lower energy
2 state resulting in one absorption band.
Listo noted after sone ormoretolesin ad! oben complex, the ter wil alsabe
same aumber of holes ina tetrahedral complex. The numberof holes in any state oa complex will
never be moe than the number of electrons 0 be excited
‘Calor oa ELE IAS TE
Electronic Spectra of High Spin d°-Octahedral Complexes
Inahigh spinoctshedral complex ofd® metal io, the d-ocbtas split into 1, (lower energy) and eg
bial (higher ener) 5 shown in te Figure 5.18,
more 1
‘Transitions of unpaired electron from fp orbital to ey orbitals are cesticted because there
willbe change ia spin multiplicity fe, these tanstions ae spin forbidden. Transition ofthat ect in
Aa wich pled a ish oppose pin tall he ote icons ca ocu besos is
in pin owe. ine de e anio of only one clecrn, tree is anion is
Similar to transition in d|-octahedrel complexes.
‘The ground state term of fe metal is SD. Inhig sin octahedral complexes *Dtemnsplts
ino STA, (ground sat) and SE, (oc st) as shown in the Figure 519, There is oly one
electronic transition om Tag 10 ŸE represented as 5, <-3 Tay. Only single absorption bad is
observed corresponding SE, «Tg tan. The absorption band broadened split because of
spin oi coupling a Jabn-Telle distortion nexctd state configurations shown in Figure 520.
Eneroy
a —
reines
| Js,
rm
| A iio ici as
Energy
Sag
“The absogtion band in he electronic seca ig spin complexes is usually found between
10000 and 11000 cm as shown in Figure 5.21. [Fe(H0)5]?* complex ion is pale green and it shows
absorption band at 11000 m“,
i
E
i
i
Electronic Spectra of d®-tetrahedral complex
Most Fe I) complexes ee octedal br baldes (X= CI”, Br”, 1") and NCS” form tetrahedral
complexes with Fe (I). I a teahedral complexes of Fe ion, the orbitals split into e Gower energy)
and f (higher energy) orbitals a shown in the Figure 522.
lion?
Transition of paied election having spin oposite to al ther electrons in e obits con occur
Because this transition is spin allowed. The ground state term for free Fe?" on (dis Sp. fn tetrahedral
complexes of Fe?" ion ° term splits nto SE (ground state) and °7> (excited state) as shown in
Figure 5.23. In {FeCi4} only single absorption band appears at 4000 em ! (near infta red region)
because of 572 «- SE transion. For {FeCly]? 8, is 4000 cm”. [FeCis
absorbe in IR region
is colourless because it
Electronic Spectra of High Spin d°-Octahedral Complexes
Inahigh spinoctshedral complex ofd® metal io, the d-ocbtas split into 1, (lower energy) and eg
bial (higher ener) 5 shown in te Figure 5.18,
more 1
‘Transitions of unpaired electron from fp orbital to ey orbitals are cesticted because there
willbe change ia spin multiplicity fe, these tanstions ae spin forbidden. Transition ofthat ect in
Aa wich pled a ish oppose pin tall he ote icons ca ocu besos is
in pin owe. ine de e anio of only one clecrn, tree is anion is
Similar to transition in d|-octahedrel complexes.
‘The ground state term of fe metal is SD. Inhig sin octahedral complexes *Dtemnsplts
ino STA, (ground sat) and SE, (oc st) as shown in the Figure 519, There is oly one
electronic transition om Tag 10 ŸE represented as 5, <-3 Tay. Only single absorption bad is
observed corresponding SE, «Tg tan. The absorption band broadened split because of
spin oi coupling a Jabn-Telle distortion nexctd state configurations shown in Figure 520.
Eneroy
a —
reines
| Js,
rm
| A iio ici as
Energy
Sag
“The absogtion band in he electronic seca ig spin complexes is usually found between
10000 and 11000 cm as shown in Figure 5.21. [Fe(H0)5]?* complex ion is pale green and it shows
absorption band at 11000 m“,
i
E
i
i
Electronic Spectra of d®-tetrahedral complex
Most Fe I) complexes ee octedal br baldes (X= CI”, Br”, 1") and NCS” form tetrahedral
complexes with Fe (I). I a teahedral complexes of Fe ion, the orbitals split into e Gower energy)
and f (higher energy) orbitals a shown in the Figure 522.
lion?
Transition of paied election having spin oposite to al ther electrons in e obits con occur
Because this transition is spin allowed. The ground state term for free Fe?" on (dis Sp. fn tetrahedral
complexes of Fe?" ion ° term splits nto SE (ground state) and °7> (excited state) as shown in
Figure 5.23. In {FeCi4} only single absorption band appears at 4000 em ! (near infta red region)
because of 572 «- SE transion. For {FeCly]? 8, is 4000 cm”. [FeCis
absorbe in IR region
is colourless because it
BEE
Electronic Spectra of d*-High Spin Octahedral Complexes
Ina big pin osha complexes ofr (4* on spit he darias into (ler ner and
(higher energy) orbital as show in Figure 5.24
‘On absorption of igh, an leiron from a 13 orbital gets excited oe oral. The ground state
term fr fee d* metal onis * Dwhich spits into * By (ground stat) and Ta (excited state} ina high
sin amp. api cla compl, cons cfa, Tea bas
2 dia erent, comporta cere ages dd)
2 a
fag Gg diy and is represented as SE. la 2-4 sti spin ocahed! complex a hole may be
do
consi g tal, Whe aston acu, e ton config eo, anne
Mere willbe atoleing rials town in Figure 5.24. This oline a rial may e laca in
hero teins dl dh dP ord, do ord dy dl, el, Meere he cntguaion
(Din echte ly deen andthe tenn corresponding is fun in excited
state is Tag. Therefore, the energy of SE, is lower (ground state) and that. ‘of Sp, is higher (excited
Ste) as shown in Figure 525.Sincethrisaotein * state, sthereisaboletrnston fiom E, to
5
Tag which represented as Ty SE This is opposite of the order of eri feb log
lower than e) as shown in igue 525,
Ugand field sueno ——>
Se
A ER SIE CAPITA
‘The absorption bend for C* high spin complexes is typically a bread band inthe region of
1600 en wih a abe tnd rund 10,000 ca" bec ree irn Da o
In Tell dito splting of fie on $ D term occurs as shown in Figure 5.26,
Due to Jee ito following three anstions ae possible:
OA By Gi “Bag Big
GE € By
‘The two bands due to 8 yy + “Big and ŸEg < °Big are assigned to superimposed. Thus, the
to ands appear which are very closer and as à result broad band appear as showin Figure 5.27.
‘opm m 1000 sm
Wave rumor m
Electronic Spectra of d*-Tetrahedral Complexes .
In tetrahedral complexes of d*-metal ion, d-orbials split into (lower energy) and 13 (higher
energy) orbitals as shown in Figure 528, but the splitin is reverse of the a high spin octahedral
complexes
Electronic Spectra of d*-High Spin Octahedral Complexes
Ina big pin osha complexes ofr (4* on spit he darias into (ler ner and
(higher energy) orbital as show in Figure 5.24
‘On absorption of igh, an leiron from a 13 orbital gets excited oe oral. The ground state
term fr fee d* metal onis * Dwhich spits into * By (ground stat) and Ta (excited state} ina high
sin amp. api cla compl, cons cfa, Tea bas
2 dia erent, comporta cere ages dd)
2 a
fag Gg diy and is represented as SE. la 2-4 sti spin ocahed! complex a hole may be
do
consi g tal, Whe aston acu, e ton config eo, anne
Mere willbe atoleing rials town in Figure 5.24. This oline a rial may e laca in
hero teins dl dh dP ord, do ord dy dl, el, Meere he cntguaion
(Din echte ly deen andthe tenn corresponding is fun in excited
state is Tag. Therefore, the energy of SE, is lower (ground state) and that. ‘of Sp, is higher (excited
Ste) as shown in Figure 525.Sincethrisaotein * state, sthereisaboletrnston fiom E, to
5
Tag which represented as Ty SE This is opposite of the order of eri feb log
lower than e) as shown in igue 525,
Ugand field sueno ——>
Se
A ER SIE CAPITA
‘The absorption bend for C* high spin complexes is typically a bread band inthe region of
1600 en wih a abe tnd rund 10,000 ca" bec ree irn Da o
In Tell dito splting of fie on $ D term occurs as shown in Figure 5.26,
Due to Jee ito following three anstions ae possible:
OA By Gi “Bag Big
GE € By
‘The two bands due to 8 yy + “Big and ŸEg < °Big are assigned to superimposed. Thus, the
to ands appear which are very closer and as à result broad band appear as showin Figure 5.27.
‘opm m 1000 sm
Wave rumor m
Electronic Spectra of d*-Tetrahedral Complexes .
In tetrahedral complexes of d*-metal ion, d-orbials split into (lower energy) and 13 (higher
energy) orbitals as shown in Figure 528, but the splitin is reverse of the a high spin octahedral
complexes
E
ee
In ere comple of d! metal in te clone configuration is 22. The 2 abies
ar wily degenerate coresponding to elenie amagement Pd di. 2, e? dl, de dl and
© 48 dy dl andthe em comesponding o this configura (grand seis $7. In a 4 -
tear complex hole may be considered in 1 ot. Whe tanston occu, he electronic
“configuration becomes el & and now there will be a hole in e-orbitals. This hole in e-orbitals can be
ctinayoftemowaysdl à dnd df Mele te coin red
‘state is doubly degenerate and the term corresponding to this state is SE
Thus, the energy of $7, i lower and that of ishigheras shown in Figure 29, This is opposite of
‘the order of energy of orbitals (e lower than 13) of d*-high spin octahedral complex.
Energy
LITE
‘There is on absorpion band in lectronie spectra due tothe SE + $77 transition.
= 527
Electronic Spectra of d?-Octahedral Complexes.
Inoctahedal complexes (whether the ligand is weak or strong} of? metal fon tike[V(H30}]°*,
he doubs pitino ng (lower energy) ande, (higher energy) orbitals The ground stat of? metal
ion in odahedal complex have two electrons wi parallel spin in any two ofthe hree lower energy
otbitals hyde and dz. The ground state, based on the 3, configuration is triply degenerate ("ig
sta) because there are tree ways of arrangement of te clero with pall spins in fn, orbital
ddl ordledly ordlydy. one elton is excited oa ey aia, he hernie configuracion
becomes ie Tea th mst stable (lowest energy) arrangement flo fos configuration
ile when the two electon are present in orbitals as fr apart as possible de, at right angle o each
coher. Far example, fone eletron is present in de orbital, Ihe abe econ vil bein the de? bia
valer an nde à oil There ae the ways o ni es to censos
popa cher dh dls die dye dy
‘Tins this sue is tiply degenerate and is reresemed as PT. This sate have lowest enerey
because to eectons occupy more space in ll he tree direton ad causes es lecron-lecron
repulsion,
“Ther san another wily degenerate arrangements ofthe two electrons in which two electrons
coocupy the bals which are relatively closer together Le, the obitas are at 45° to each othr
dd, oda hd Ts rungen ar te sao wilbeiterm
nergy because bah electrons occupy space only inone plan,
ee
In ere comple of d! metal in te clone configuration is 22. The 2 abies
ar wily degenerate coresponding to elenie amagement Pd di. 2, e? dl, de dl and
© 48 dy dl andthe em comesponding o this configura (grand seis $7. In a 4 -
tear complex hole may be considered in 1 ot. Whe tanston occu, he electronic
“configuration becomes el & and now there will be a hole in e-orbitals. This hole in e-orbitals can be
ctinayoftemowaysdl à dnd df Mele te coin red
‘state is doubly degenerate and the term corresponding to this state is SE
Thus, the energy of $7, i lower and that of ishigheras shown in Figure 29, This is opposite of
‘the order of energy of orbitals (e lower than 13) of d*-high spin octahedral complex.
Energy
LITE
‘There is on absorpion band in lectronie spectra due tothe SE + $77 transition.
= 527
Electronic Spectra of d?-Octahedral Complexes.
Inoctahedal complexes (whether the ligand is weak or strong} of? metal fon tike[V(H30}]°*,
he doubs pitino ng (lower energy) ande, (higher energy) orbitals The ground stat of? metal
ion in odahedal complex have two electrons wi parallel spin in any two ofthe hree lower energy
otbitals hyde and dz. The ground state, based on the 3, configuration is triply degenerate ("ig
sta) because there are tree ways of arrangement of te clero with pall spins in fn, orbital
ddl ordledly ordlydy. one elton is excited oa ey aia, he hernie configuracion
becomes ie Tea th mst stable (lowest energy) arrangement flo fos configuration
ile when the two electon are present in orbitals as fr apart as possible de, at right angle o each
coher. Far example, fone eletron is present in de orbital, Ihe abe econ vil bein the de? bia
valer an nde à oil There ae the ways o ni es to censos
popa cher dh dls die dye dy
‘Tins this sue is tiply degenerate and is reresemed as PT. This sate have lowest enerey
because to eectons occupy more space in ll he tree direton ad causes es lecron-lecron
repulsion,
“Ther san another wily degenerate arrangements ofthe two electrons in which two electrons
coocupy the bals which are relatively closer together Le, the obitas are at 45° to each othr
dd, oda hd Ts rungen ar te sao wilbeiterm
nergy because bah electrons occupy space only inone plan,
EAT TN Cot OE,
Reese ES
If oh be electrons ae excited to ez orbitals, there à only one arrangement of two electrons with
parallel spins.
dd
By “FP
ly non-degenerate and canbe represented as * 439.
‘Thus, there are three transitions from ground state to excite states ofthe same multiplicity, The
luce electronic transitions for d?-oetahedral complex are shown in Figure 5.31
‘This state is electron
Least ene
En
= A
Cda a
Hoe cory
we
E
Bec slo
= 11
dde
Mostar
a
AAA
Ground ate Exodo
as
The tems ring for d®-coniguation ro °F, 3, 5, Wand UG outof which isthe ground
te erm. The excited state of maximum mulipiity (=3) is only À An octahedral complexes 3F
mm splits into #71, (F), Tag (F) ad Age (F) The em IP doesnot spit in octahedral complexes
tearsforms into? 7g (P) term and energy ofthe ems vate a the ligand Til strength is
gods shown in Figure 532. The to 7j sates ar dainguihed by adding the symbol (£)or(P)
tat *Tig temo as ?Tig(F) and M7 (P) The ground sate term of d'in octahedral complex is
Tig (FJand excited states are 3735, * Ayyand Tig (P), Thre spin allowed transitions ae possible as
own below:
Mag Te m)
as Te Cr)
and Mg Os)
‘Transitions from PT}, ground state to any ofthe singlet sites are spin forbidden. Therefore, only
three absorption bands may appear in he spectrum of[V(H20)6
The separation between te ground sae ig (F)andihe exited states Tag, ? ag and Tip (2)
ineresses with increase in ligand field strength. Thus as he ligand field strength increases, the transitions
rep Higher energies andthe absorption bands shit towards the UV-egion.
For[V(H¿O)g]”* which shows blue colour, two absorption bands coresponding o "Tag *Tig
and ig) € Pier observed in vise rot 170 naná 2570 e
he rs a ae a nb dl 8
‘respecively.
“The third transition Ay, + *Tigcomesponds to excitation of both clectrons and requires high
ig The, tad one di anni cr eerily
respectively.
et) 35 and 66
observed. Also ths band is hie by a high intensity charge tansfer band in he UV-region. Al he
‘tree bands ae observed when VÍ" is incorporie ini AL¿O3 corundum lattice in which a small
portion of AI™* have been replaced by Y? ins
aay he) Erlen
scan be seen rom the Figure 5.32 thatthelowestensigy ration 3 735 < Fi givesthe value of
A, Le, difference between the energy of Tig and 77, is (02 -(-0.8)] Ay = A
However, the 37, (F) state can mix with 7 (P) ate causing a slight curvature, Therefore, the
energy of Tay < ig will not give the exact vale of,
Alternatively the difference between the energy of first wanstion (Tag <= *Tig) and tht of
second transition Bug < 37, ) gives the value of, Usually the separation between Grat and thd
bands gives the value of Ag,
4
Reese ES
If oh be electrons ae excited to ez orbitals, there à only one arrangement of two electrons with
parallel spins.
dd
By “FP
ly non-degenerate and canbe represented as * 439.
‘Thus, there are three transitions from ground state to excite states ofthe same multiplicity, The
luce electronic transitions for d?-oetahedral complex are shown in Figure 5.31
‘This state is electron
Least ene
En
= A
Cda a
Hoe cory
we
E
Bec slo
= 11
dde
Mostar
a
AAA
Ground ate Exodo
as
The tems ring for d®-coniguation ro °F, 3, 5, Wand UG outof which isthe ground
te erm. The excited state of maximum mulipiity (=3) is only À An octahedral complexes 3F
mm splits into #71, (F), Tag (F) ad Age (F) The em IP doesnot spit in octahedral complexes
tearsforms into? 7g (P) term and energy ofthe ems vate a the ligand Til strength is
gods shown in Figure 532. The to 7j sates ar dainguihed by adding the symbol (£)or(P)
tat *Tig temo as ?Tig(F) and M7 (P) The ground sate term of d'in octahedral complex is
Tig (FJand excited states are 3735, * Ayyand Tig (P), Thre spin allowed transitions ae possible as
own below:
Mag Te m)
as Te Cr)
and Mg Os)
‘Transitions from PT}, ground state to any ofthe singlet sites are spin forbidden. Therefore, only
three absorption bands may appear in he spectrum of[V(H20)6
The separation between te ground sae ig (F)andihe exited states Tag, ? ag and Tip (2)
ineresses with increase in ligand field strength. Thus as he ligand field strength increases, the transitions
rep Higher energies andthe absorption bands shit towards the UV-egion.
For[V(H¿O)g]”* which shows blue colour, two absorption bands coresponding o "Tag *Tig
and ig) € Pier observed in vise rot 170 naná 2570 e
he rs a ae a nb dl 8
‘respecively.
“The third transition Ay, + *Tigcomesponds to excitation of both clectrons and requires high
ig The, tad one di anni cr eerily
respectively.
et) 35 and 66
observed. Also ths band is hie by a high intensity charge tansfer band in he UV-region. Al he
‘tree bands ae observed when VÍ" is incorporie ini AL¿O3 corundum lattice in which a small
portion of AI™* have been replaced by Y? ins
aay he) Erlen
scan be seen rom the Figure 5.32 thatthelowestensigy ration 3 735 < Fi givesthe value of
A, Le, difference between the energy of Tig and 77, is (02 -(-0.8)] Ay = A
However, the 37, (F) state can mix with 7 (P) ate causing a slight curvature, Therefore, the
energy of Tay < ig will not give the exact vale of,
Alternatively the difference between the energy of first wanstion (Tag <= *Tig) and tht of
second transition Bug < 37, ) gives the value of, Usually the separation between Grat and thd
bands gives the value of Ag,
4
BROS AOI A
Energy of * 497 € "Ty transition - Energy of Ti < y transition =28 6 80
Unfortunately, he third end cannot alays observed insuch cae more complicated ali
is quid which il e discussed in Tanabe- Sugano digsem on page 5.48.
As the ligand field strength increases the * Az, and "Tig (P) states cross each other and energy
of dag becomes higher han hat of *7g(P). For songe and the energy of? Aig © ig F)
‘becomes higher than that of *Tig(P)< Ti (F).
‘Ator near the cross over poiattwo bands iz. 49e < *Tigand Ti (P) € ig (F)camovertap
each other and thas ony two band ar observed (Figur 53)
Foran extremely weak ligand otahedal
complex, three sbsomtion bends
Goresponding 10 tree tension as
discussed caer are obtained and de y
Separation betweeo fist and third bado E
gives th value of i
Electronic Spectra of
d?-Totrahedral Complexes
In tetrahedral complexes of 2 metals 0900 15000 20000 25000 ano
fonslike[VCl,]” and Ve)” the db vase nue (re
split into e (lower energy) and f (higher BER
energy) orbitals giving rise to electronic
contain 6749. a ground state ther is only one arrangement of two electro with parallel spas
da. #
electrons is excited to a fy orbital, he electronic configuration becomes e. Corresponding to this
electronic configuration, the lower energy tat wll be that when he two electronsate presento
a5 far apart as possible. The two elecrons can be arranged in either of the three ways : d', di
al! Ths hist clone on degenerate and isrepresentedas dp, oseoftherwo
bad a! eas
dl 7 dental, io Thr ie sil degenerate ais reprsenedas This
anche pet ae corespoding to configuran in wich th two electo ocu he ia
whch ately impr dl, dd daddy Tissot enya
is represented as Ÿ7j. If both the clectrons are excited to tz orbitals, the electronic configuration
becomes 092. Comesponding o ths ni configuration, thee ar thee ways of arungenet of
two electron in any ofthe rs bis of ceba: al, dl dla lady dl Thee is
sate is once again is triply degenerate and is represented as 27; (P), This state i-of highest energy.
ls has beenseentb he oder of energies ofthese ttes 43, 273, 7 reve fi cnrs of]
3 dag, Mag and Tig ford octahedral complexes.
“The terms having same spin multiplicity arising for” configuration ae °F and *P.5F is the
round sta tom, The P sate dos na sl na complex but > state splits it © 47,977 and 7,
states in tetrabedral complex as ovni Figure 5.4,
m
‘Three possible ranshions are
mes
eh
TS
Electronic Spectra of d°-Octahedral Complexes
In a octahedel complexes, the orbits split ito tae (lower energy) and (higher energy)
«bits. Tho, in ground ste the cie configuration is 1, «2. her only one lerne
rangement for this electronic configuration 4
gl
a , and the ground state tenn
corresponding to this configuration is mpresentedas 3477.
la ad octahedral complex two boles may be considered in eg orbitals as shown in Figure 535.
vam
wit,
Bes
When a electron om any oft ai exited to any one ofthe ag oral, he ecnie
configuracion Becomes À, e. Now dre willbe two holes one In ag and one ine ral
‘Corresponding to tis electronic configuration, thee are two triply degenerate states. The lower energy
Energy of * 497 € "Ty transition - Energy of Ti < y transition =28 6 80
Unfortunately, he third end cannot alays observed insuch cae more complicated ali
is quid which il e discussed in Tanabe- Sugano digsem on page 5.48.
As the ligand field strength increases the * Az, and "Tig (P) states cross each other and energy
of dag becomes higher han hat of *7g(P). For songe and the energy of? Aig © ig F)
‘becomes higher than that of *Tig(P)< Ti (F).
‘Ator near the cross over poiattwo bands iz. 49e < *Tigand Ti (P) € ig (F)camovertap
each other and thas ony two band ar observed (Figur 53)
Foran extremely weak ligand otahedal
complex, three sbsomtion bends
Goresponding 10 tree tension as
discussed caer are obtained and de y
Separation betweeo fist and third bado E
gives th value of i
Electronic Spectra of
d?-Totrahedral Complexes
In tetrahedral complexes of 2 metals 0900 15000 20000 25000 ano
fonslike[VCl,]” and Ve)” the db vase nue (re
split into e (lower energy) and f (higher BER
energy) orbitals giving rise to electronic
contain 6749. a ground state ther is only one arrangement of two electro with parallel spas
da. #
electrons is excited to a fy orbital, he electronic configuration becomes e. Corresponding to this
electronic configuration, the lower energy tat wll be that when he two electronsate presento
a5 far apart as possible. The two elecrons can be arranged in either of the three ways : d', di
al! Ths hist clone on degenerate and isrepresentedas dp, oseoftherwo
bad a! eas
dl 7 dental, io Thr ie sil degenerate ais reprsenedas This
anche pet ae corespoding to configuran in wich th two electo ocu he ia
whch ately impr dl, dd daddy Tissot enya
is represented as Ÿ7j. If both the clectrons are excited to tz orbitals, the electronic configuration
becomes 092. Comesponding o ths ni configuration, thee ar thee ways of arungenet of
two electron in any ofthe rs bis of ceba: al, dl dla lady dl Thee is
sate is once again is triply degenerate and is represented as 27; (P), This state i-of highest energy.
ls has beenseentb he oder of energies ofthese ttes 43, 273, 7 reve fi cnrs of]
3 dag, Mag and Tig ford octahedral complexes.
“The terms having same spin multiplicity arising for” configuration ae °F and *P.5F is the
round sta tom, The P sate dos na sl na complex but > state splits it © 47,977 and 7,
states in tetrabedral complex as ovni Figure 5.4,
m
‘Three possible ranshions are
mes
eh
TS
Electronic Spectra of d°-Octahedral Complexes
In a octahedel complexes, the orbits split ito tae (lower energy) and (higher energy)
«bits. Tho, in ground ste the cie configuration is 1, «2. her only one lerne
rangement for this electronic configuration 4
gl
a , and the ground state tenn
corresponding to this configuration is mpresentedas 3477.
la ad octahedral complex two boles may be considered in eg orbitals as shown in Figure 535.
vam
wit,
Bes
When a electron om any oft ai exited to any one ofthe ag oral, he ecnie
configuracion Becomes À, e. Now dre willbe two holes one In ag and one ine ral
‘Corresponding to tis electronic configuration, thee are two triply degenerate states. The lower energy
atte wil aise when two holes occupy the orbital as fr apart as posible, This ste is presented as
ra. Theo may be presenter dy 01d o da, OF dard fil ings oser
repulsion between two holes because two holes occupy more space in x, and seins Holes are
effected inthe oposite way compare to electron. There san another triply degenerate arangement
of two holes in which the two holes occupy the orbitals which are closer together. The holes may be
present ineiherdyy dsp Ode da 00d dx orbital, This isofbigher energy andi represented
as Ti
‘When bo he eecrns ae exited he electronic configuration becomes 1,
arepresentinany ofthe of, oils either In dy dz Orr du ot dy da oil Therefore, is
states pl degenerate dis represented as T, (P) Since double excision requires Higher ner,
therefore, Ti states ofhighest energy state. There are four energy stats including ground state. Ths,
there are three wanstons. The rarstons of holes is similar to electronic tas.
‘The ters having same multiplicity arising o: d®-configuration are °F, 37, The °F satis the
ground slt. oeil complex °F term split into? Age, 72 and Tg as shown in Figure 536.
‘The term P does at split batt ransforns into * 7), (P) state.
PIP) Wet) Ema xa roba,
2088,
N
Now vo holes
un Oe)
‘When ligand ld strength increases, there wil be bending of * Tig (F) and Ti (P)lines because
these states are of sae symmetry and there is inter-electonic repulsion (or mixing of two Tig states).
‘This electronic repulsion lowers tke energy of lower state and increases energy ofthe higher slate. Thus,
de to inter-eletronic repulsion the two Ti states do not cross. This is called nan-crossing rule.
Electronic spectre of octahedral Ni (M), 4complexes usually consist of three bands according tothe
following tensions
Ma em
AE) Fay
Sie) € dag = vs
“The lowest energy tansion£e, Tag € Ang gives the value of By
Absorbance
MOOD 15000 20000 25000 50000
Wave number fan) >
For[Ni(H20)5]”* complex three absorption bands are observed at 8700 eur, 14500 cm" and
25300 cu. Lowest tansiion Le, 2734 € Ag gives the value of A because May «24
tansion=-024,-C124,)=A.
Therefore, for[NIGEZO)S]”* is 8700 cr
Because of hr Teller distortion in excited sate the middle peak is bod (velapping of two
spliting pea =
Electronic Spectra for d®-Tetrahedral Complexes
\ For d* metal ion in tetrahedral fields, he spliting of the free ion ground state term is the inverse of |
is sing octahedra elds a shown in the Figure 538
ag, if) EaL08x2 04x
Le SET eee
e) 6%)
Te (eM) E-HO6x3+04x 94
24
be
AE
wig) Estosxesoaxg
CN
ip la strength —
“The following three transition ae possible for d°-tetrahedral complexes:
ner
ne
en
‘Corresponding to these transitions, three relatively intense bands are expected. For [NiCla ]?” two.
‘bands are observed at 7549 oui, 14250-15240 cor” as shown in Figure 5.39.
ra. Theo may be presenter dy 01d o da, OF dard fil ings oser
repulsion between two holes because two holes occupy more space in x, and seins Holes are
effected inthe oposite way compare to electron. There san another triply degenerate arangement
of two holes in which the two holes occupy the orbitals which are closer together. The holes may be
present ineiherdyy dsp Ode da 00d dx orbital, This isofbigher energy andi represented
as Ti
‘When bo he eecrns ae exited he electronic configuration becomes 1,
arepresentinany ofthe of, oils either In dy dz Orr du ot dy da oil Therefore, is
states pl degenerate dis represented as T, (P) Since double excision requires Higher ner,
therefore, Ti states ofhighest energy state. There are four energy stats including ground state. Ths,
there are three wanstons. The rarstons of holes is similar to electronic tas.
‘The ters having same multiplicity arising o: d®-configuration are °F, 37, The °F satis the
ground slt. oeil complex °F term split into? Age, 72 and Tg as shown in Figure 536.
‘The term P does at split batt ransforns into * 7), (P) state.
PIP) Wet) Ema xa roba,
2088,
N
Now vo holes
un Oe)
‘When ligand ld strength increases, there wil be bending of * Tig (F) and Ti (P)lines because
these states are of sae symmetry and there is inter-electonic repulsion (or mixing of two Tig states).
‘This electronic repulsion lowers tke energy of lower state and increases energy ofthe higher slate. Thus,
de to inter-eletronic repulsion the two Ti states do not cross. This is called nan-crossing rule.
Electronic spectre of octahedral Ni (M), 4complexes usually consist of three bands according tothe
following tensions
Ma em
AE) Fay
Sie) € dag = vs
“The lowest energy tansion£e, Tag € Ang gives the value of By
Absorbance
MOOD 15000 20000 25000 50000
Wave number fan) >
For[Ni(H20)5]”* complex three absorption bands are observed at 8700 eur, 14500 cm" and
25300 cu. Lowest tansiion Le, 2734 € Ag gives the value of A because May «24
tansion=-024,-C124,)=A.
Therefore, for[NIGEZO)S]”* is 8700 cr
Because of hr Teller distortion in excited sate the middle peak is bod (velapping of two
spliting pea =
Electronic Spectra for d®-Tetrahedral Complexes
\ For d* metal ion in tetrahedral fields, he spliting of the free ion ground state term is the inverse of |
is sing octahedra elds a shown in the Figure 538
ag, if) EaL08x2 04x
Le SET eee
e) 6%)
Te (eM) E-HO6x3+04x 94
24
be
AE
wig) Estosxesoaxg
CN
ip la strength —
“The following three transition ae possible for d°-tetrahedral complexes:
ner
ne
en
‘Corresponding to these transitions, three relatively intense bands are expected. For [NiCla ]?” two.
‘bands are observed at 7549 oui, 14250-15240 cor” as shown in Figure 5.39.
ASAS
1549 om Caen)
= 188-3774 em
“The band appears at 14250-15240 em is due to Jakn-Teller dstoton,
‘The 37, © PT, transition shows an absorption band at 3400 ca” hu itis not observed in visible
region because it lies
$000 10.000 16000 2000 2500
Electronic Spectra of d” High Spin Octahedral Complexes
“The be on ground state tem forCo™* (is andi ter tem id same pin mulipiciy of
higher energy is 47, a high spin octahedal complexes the sping of 4F st is same as for
doce complexe. The 4F term splis into “Tig, “Pag and Ages as shown inthe
Figure $40. tn, D Estrie
PRE
se Se)
sche) Eakadxesasey
wea
Ex
Enero
Sig 146)
Da ang
Erposnssünud]a
086,
For crystal of KCoF in which Co?" jon is surounded octahealy by six” ligands.
‘There are thee absorption bands at 7150 em, 15200 en and 19200 om comesponding 10 three
trsions.
{Ty E Tigo meisten!
4 dag E Tig, vy 15200 cm"
Tg P) E Tig, vp =19200 em"
Lower transition (“Tag < “Tig} may give the value of &, because Tag + Tigtransition (vy)
i025 -(-084,)= 4,
But this does not allow tor the configuration interaction (binding o lines) between *71,() and
ig (P)states. In this case separation between frst (v, )and the second band (v2) gives the value of A.
because this is not effected by configuration interaction.
men=do
5200-7200
000 x
Absorption spectra of ¿CoF; is shown in Figure 5 A.
Ansormance
À
500 1000 1500 20000 25000
ais Se
Absorption Spectrum of [Co(H>0)s?* Complex ion 228
InlCofH0)6}?* complex ion, the spectrum usually consists ofa weak band innear infrared region
at 8000 ca. This band is assigned as m =“T,¿(F)e>Tig(F). An anoier band appears at
approximately 20000 em” This band is consderedto be comprising tree overlaping peaks. This band
has tree peaks at 16000 cm, 19400 cr and 21600 om, Two peaks observed at 16000 en und
19400 em’ comespond to *Azg <= “Tig and *7i,(P)«- "Zi transitions. Since these (wo transitions
tue near the cross over point of * An, and ‘Tig (P) states, therefore, two peaks overlap one another
org a shoulder in the spectrum.
1549 om Caen)
= 188-3774 em
“The band appears at 14250-15240 em is due to Jakn-Teller dstoton,
‘The 37, © PT, transition shows an absorption band at 3400 ca” hu itis not observed in visible
region because it lies
$000 10.000 16000 2000 2500
Electronic Spectra of d” High Spin Octahedral Complexes
“The be on ground state tem forCo™* (is andi ter tem id same pin mulipiciy of
higher energy is 47, a high spin octahedal complexes the sping of 4F st is same as for
doce complexe. The 4F term splis into “Tig, “Pag and Ages as shown inthe
Figure $40. tn, D Estrie
PRE
se Se)
sche) Eakadxesasey
wea
Ex
Enero
Sig 146)
Da ang
Erposnssünud]a
086,
For crystal of KCoF in which Co?" jon is surounded octahealy by six” ligands.
‘There are thee absorption bands at 7150 em, 15200 en and 19200 om comesponding 10 three
trsions.
{Ty E Tigo meisten!
4 dag E Tig, vy 15200 cm"
Tg P) E Tig, vp =19200 em"
Lower transition (“Tag < “Tig} may give the value of &, because Tag + Tigtransition (vy)
i025 -(-084,)= 4,
But this does not allow tor the configuration interaction (binding o lines) between *71,() and
ig (P)states. In this case separation between frst (v, )and the second band (v2) gives the value of A.
because this is not effected by configuration interaction.
men=do
5200-7200
000 x
Absorption spectra of ¿CoF; is shown in Figure 5 A.
Ansormance
À
500 1000 1500 20000 25000
ais Se
Absorption Spectrum of [Co(H>0)s?* Complex ion 228
InlCofH0)6}?* complex ion, the spectrum usually consists ofa weak band innear infrared region
at 8000 ca. This band is assigned as m =“T,¿(F)e>Tig(F). An anoier band appears at
approximately 20000 em” This band is consderedto be comprising tree overlaping peaks. This band
has tree peaks at 16000 cm, 19400 cr and 21600 om, Two peaks observed at 16000 en und
19400 em’ comespond to *Azg <= “Tig and *7i,(P)«- "Zi transitions. Since these (wo transitions
tue near the cross over point of * An, and ‘Tig (P) states, therefore, two peaks overlap one another
org a shoulder in the spectrum.
SEEN
“The extra band which appears at 21600 cm is du to sp obit coupling or transition o another
state of lower spin multiplicity.
In some cases vz is not observed but the fie peaks arise fram spliting of term due to spin obit
coupling or Jahn-Teller distortion in excited stat,
‘The spectrum of Co(H,0)4]" is shown in Figure 542,
|
i
Electronic Spectra of d”-tetrahedral Complexes
Ina tetrahedral complex ion, say[CoCH, P" thespliting of frevion ground tems the reverse ofi
in octahedral complexes so that for d7-ion in tetrahedral complex * Az is of lowest energy. There are
thee possible ansions
net, neo IR region)
“net, OR region)
and TA, (Visible region)
Only one band corresponding to *7; (P) +- "Az appears in visible region at 14700 cnt (#3).
“Two bands corresponding to "7, «4p and Ÿ7i(F) + 44p appear at 3300 em" (y) and 5500
en (2) respectively. These two bands ar inte region. The electronic anio ae shonin
Figure 543, an E=tOoH2 04x54
008%
Un e
Absorption spectrum of CoC]? complexions shown a Figure 54.
For{CoCl4]? ion, A, is the energy difference between “42 and ‘Tp states.
8y=(-02-(12]A, =3300 cn"
Wave rama)
Tevahedal complex [COC is more intensely blue in colour whereas the high spin
comple of Co ion ar of fit colour
‘The intense colour of {CoC}? ttrabedral complex io is due to:
Laporte pat allowed ce, there is some pd mixing,
ons ae spin allowed.
“The faint colour o high spin complexes of Co?" on sd to
@ da wansion is Laporte frien
(D aed transitions is spin allowed.
Electronic Spectra of d*. Octahedral Complexes
Ind? octahedral complexes the debi split into tng lower energy) and ez (higher energy)
vital. Therefore, in ground sae he lerne configuration 5, and there are two hoes ine
bit (Figure 545) gee
LT
The isonlyore econ armement cospntigt his lector configuon e, e, e
(ch, dh ef) Therefore, isarangenentsclecooicaly non-degenerate sd can be represetedas
5
ag.
“The extra band which appears at 21600 cm is du to sp obit coupling or transition o another
state of lower spin multiplicity.
In some cases vz is not observed but the fie peaks arise fram spliting of term due to spin obit
coupling or Jahn-Teller distortion in excited stat,
‘The spectrum of Co(H,0)4]" is shown in Figure 542,
|
i
Electronic Spectra of d”-tetrahedral Complexes
Ina tetrahedral complex ion, say[CoCH, P" thespliting of frevion ground tems the reverse ofi
in octahedral complexes so that for d7-ion in tetrahedral complex * Az is of lowest energy. There are
thee possible ansions
net, neo IR region)
“net, OR region)
and TA, (Visible region)
Only one band corresponding to *7; (P) +- "Az appears in visible region at 14700 cnt (#3).
“Two bands corresponding to "7, «4p and Ÿ7i(F) + 44p appear at 3300 em" (y) and 5500
en (2) respectively. These two bands ar inte region. The electronic anio ae shonin
Figure 543, an E=tOoH2 04x54
008%
Un e
Absorption spectrum of CoC]? complexions shown a Figure 54.
For{CoCl4]? ion, A, is the energy difference between “42 and ‘Tp states.
8y=(-02-(12]A, =3300 cn"
Wave rama)
Tevahedal complex [COC is more intensely blue in colour whereas the high spin
comple of Co ion ar of fit colour
‘The intense colour of {CoC}? ttrabedral complex io is due to:
Laporte pat allowed ce, there is some pd mixing,
ons ae spin allowed.
“The faint colour o high spin complexes of Co?" on sd to
@ da wansion is Laporte frien
(D aed transitions is spin allowed.
Electronic Spectra of d*. Octahedral Complexes
Ind? octahedral complexes the debi split into tng lower energy) and ez (higher energy)
vital. Therefore, in ground sae he lerne configuration 5, and there are two hoes ine
bit (Figure 545) gee
LT
The isonlyore econ armement cospntigt his lector configuon e, e, e
(ch, dh ef) Therefore, isarangenentsclecooicaly non-degenerate sd can be represetedas
5
ag.
ES
25
‘This case is similar to d®-ociahedrl complex. When an electron is excited to any one of the eg
bias, te leconi eonfgusion becomes, el. Now there are two Roles, one ina ade in,
orbitals. There are two triply degenerate arrangements of holes corresponding to this electronic
gueto. The lower energy sat wl ase when two holes oceapy te ols as far pe 25
possible Therefore, the wo ots may best erin doy, or de da. 7 00d à Th,
this state is teiply degenerate and is represented as Ta.
“Theres another ny gene agement of wo holes in which two holes copy bals
veicharclosrtogir Th haeamaybepreuteierind,, 42. 7 01d) rad, odia
‘This state is of higher energy and is represented as Ti.
‘When wo cleus ae exce tools e electronic configuration becomes, Now
evo hole re presenti 000 y il ithrndy dy orde de Fd de obit Th, his state
is triply degenerate and have highest energy. This stat is represented as * Tig (P)
“Therefor, there are tre tans af holes fom ground states 10 tre oe excited at
‘Transition of holes similar estes aso.
‘The terms for d*-metal cation having same spin multiplicity (= 4) are *F and “Po For
4>-configuration *F tem is the ground state and “P term is of higher energy. in octahedral complex
SF term splits into "Tig, “Tag and * dgg sates as showin Figure 5.46, The 4 term does nat spit but
transforms into “Ti, (P) state.
‘When ligand field strength increase, there willbe beading of *7ig(F) and “Ty (Pines because
these have same symmetry and there sclctron electron repulsion (mixing of two “Tig stats). This
rising lower the energy of lower ste, *Tig(F)and increase the energy of higher state, "Tig (P) in
equal amount. Therefore, due to mixing the two Tig states do not ross each other,
“There are three possible spin allowed ad transitions.
{Tag A ag IC
EN Ag, ment | For Cree
RP té , | EM em
D Enboder s06x 214,
mn D es
Energy
hy By EEE 2208,
‘Ligand field streng — =
‘These transitions are resposibe fr three absorbance bands in elestronie spectrum? -octhedral
‘complexes. For {CH} dee absorption bands occur at 14900 ca, 22700 em and 34400 em
(One ded transition with lowest energy (“Tag <-*A2g is a direct measure of the crystal fed
spliting à, ort0D,.
(128,)= 14900 cm. (+)
028,
“Two bands are observedin visible region hu thied band corresponding o y isweakandisobserved
in UV region. Electonicspecturm fr[CtFe] "is shown in Figure 5.47.
ing of Fand *P tem including mixing of two states {7 (F) and "Tig (Pis shown
in Figure 5.48,
rg
25
‘This case is similar to d®-ociahedrl complex. When an electron is excited to any one of the eg
bias, te leconi eonfgusion becomes, el. Now there are two Roles, one ina ade in,
orbitals. There are two triply degenerate arrangements of holes corresponding to this electronic
gueto. The lower energy sat wl ase when two holes oceapy te ols as far pe 25
possible Therefore, the wo ots may best erin doy, or de da. 7 00d à Th,
this state is teiply degenerate and is represented as Ta.
“Theres another ny gene agement of wo holes in which two holes copy bals
veicharclosrtogir Th haeamaybepreuteierind,, 42. 7 01d) rad, odia
‘This state is of higher energy and is represented as Ti.
‘When wo cleus ae exce tools e electronic configuration becomes, Now
evo hole re presenti 000 y il ithrndy dy orde de Fd de obit Th, his state
is triply degenerate and have highest energy. This stat is represented as * Tig (P)
“Therefor, there are tre tans af holes fom ground states 10 tre oe excited at
‘Transition of holes similar estes aso.
‘The terms for d*-metal cation having same spin multiplicity (= 4) are *F and “Po For
4>-configuration *F tem is the ground state and “P term is of higher energy. in octahedral complex
SF term splits into "Tig, “Tag and * dgg sates as showin Figure 5.46, The 4 term does nat spit but
transforms into “Ti, (P) state.
‘When ligand field strength increase, there willbe beading of *7ig(F) and “Ty (Pines because
these have same symmetry and there sclctron electron repulsion (mixing of two “Tig stats). This
rising lower the energy of lower ste, *Tig(F)and increase the energy of higher state, "Tig (P) in
equal amount. Therefore, due to mixing the two Tig states do not ross each other,
“There are three possible spin allowed ad transitions.
{Tag A ag IC
EN Ag, ment | For Cree
RP té , | EM em
D Enboder s06x 214,
mn D es
Energy
hy By EEE 2208,
‘Ligand field streng — =
‘These transitions are resposibe fr three absorbance bands in elestronie spectrum? -octhedral
‘complexes. For {CH} dee absorption bands occur at 14900 ca, 22700 em and 34400 em
(One ded transition with lowest energy (“Tag <-*A2g is a direct measure of the crystal fed
spliting à, ort0D,.
(128,)= 14900 cm. (+)
028,
“Two bands are observedin visible region hu thied band corresponding o y isweakandisobserved
in UV region. Electonicspecturm fr[CtFe] "is shown in Figure 5.47.
ing of Fand *P tem including mixing of two states {7 (F) and "Tig (Pis shown
in Figure 5.48,
rg
Sn(CtH,0}6)* complex ion thee bands appear at 17400 cm, 24700 em and 37800 cm". The
high energy band 37800 car! is weak and i assigned due to promotion of two holes and is hidden by
charge transfer band.
Cr?" ion does nat form etrahedal complexes, therefore, spectra of Cr ion intetrahedal complex.
can not be interested here.
Combined Orgel diagram for d?,4?, 4? and d* octahedral and tetrahedral complex is shown in
Figure 5.9.
Sen ek
mort
itor
TT
‘idsteagth old strength |
a Q
cata a sha
a] oda
FUE
Electronic Spectra of d°-High Spin Octahedral Complexes
In high spin octahedral complexes of metal ionsike, (Ma(H)0)¢ J, [Fe] d-otbitals split.
int ay (owerenrgy) ande, (higher energy) rials andthe electronic configura ome, e
In hese complees tee ae ve unpaired electrons wth parallel spas, Any del eansioniavolves
reversal of spins, Thus, dd transitions are spin forbidden. Also d-d transitions are Laporte forbidden
because of presence of ente of symmetry. Therefore, these complexes ae very fan elated or
colourless (MAI) à ae pink and [Fee is pale vol coloured. The rend state term for
<° free metal ion is 6 which does not split in octahedral feld but transforms into © Ay. There are Ro
| excited satesof he same pi mule (6) and, therefore, here villbenopinaoweduansiions.
‘There are 11 excited states ford fre meta ion but none of them have spin apc equal osx,
Among these LL excited states four sates have spin mullpiiy of 4 and these tates ac “2, *D, 4F
and “6. Inhighspinoctahedra field these states splits 1 give total numberof Wexctd states wich re
{Tig (P), “Tag(D), ELLO), “Tig (E), “Tae (F), “Ang (E) » Aig G), "Er “Tig G) and
Tag (6) The dd anio to these states involve the reversal of oly one pi. The ec stes ao
doublets and dans se states is doubly spin forbidden and re ot observed. There may be
cen aed tanstons to the ten quartets but these are very weak. The absorption oc for
MO) isshown in Figure 5.50. The * Ag and “E, peak are uresovelin the spectrum, The
molar absorbance is 092003 Lo em
la Orgel diagam of [Ma(H0}6)"*, the Aig fine is hou Al the
TEL) “By (D) “tag (FYand44,, (G)lines are also parallel to § Aig lines, there isno change in
energy due o change in and and vibrations. Ths, transitions 1 bso ses ive eto hp peaks
but peaks are extreme weak The “Ty (G) and “Tag (6) ins ae not pall Sy Hine because
thei energy is ange wih change is igands and thus ransions to thse ses provid road peaks.
Es 1000
gend tá strength (ea)
som 10/00 15000 200 25000 pm as
Wave number (m) —
high energy band 37800 car! is weak and i assigned due to promotion of two holes and is hidden by
charge transfer band.
Cr?" ion does nat form etrahedal complexes, therefore, spectra of Cr ion intetrahedal complex.
can not be interested here.
Combined Orgel diagram for d?,4?, 4? and d* octahedral and tetrahedral complex is shown in
Figure 5.9.
Sen ek
mort
itor
TT
‘idsteagth old strength |
a Q
cata a sha
a] oda
FUE
Electronic Spectra of d°-High Spin Octahedral Complexes
In high spin octahedral complexes of metal ionsike, (Ma(H)0)¢ J, [Fe] d-otbitals split.
int ay (owerenrgy) ande, (higher energy) rials andthe electronic configura ome, e
In hese complees tee ae ve unpaired electrons wth parallel spas, Any del eansioniavolves
reversal of spins, Thus, dd transitions are spin forbidden. Also d-d transitions are Laporte forbidden
because of presence of ente of symmetry. Therefore, these complexes ae very fan elated or
colourless (MAI) à ae pink and [Fee is pale vol coloured. The rend state term for
<° free metal ion is 6 which does not split in octahedral feld but transforms into © Ay. There are Ro
| excited satesof he same pi mule (6) and, therefore, here villbenopinaoweduansiions.
‘There are 11 excited states ford fre meta ion but none of them have spin apc equal osx,
Among these LL excited states four sates have spin mullpiiy of 4 and these tates ac “2, *D, 4F
and “6. Inhighspinoctahedra field these states splits 1 give total numberof Wexctd states wich re
{Tig (P), “Tag(D), ELLO), “Tig (E), “Tae (F), “Ang (E) » Aig G), "Er “Tig G) and
Tag (6) The dd anio to these states involve the reversal of oly one pi. The ec stes ao
doublets and dans se states is doubly spin forbidden and re ot observed. There may be
cen aed tanstons to the ten quartets but these are very weak. The absorption oc for
MO) isshown in Figure 5.50. The * Ag and “E, peak are uresovelin the spectrum, The
molar absorbance is 092003 Lo em
la Orgel diagam of [Ma(H0}6)"*, the Aig fine is hou Al the
TEL) “By (D) “tag (FYand44,, (G)lines are also parallel to § Aig lines, there isno change in
energy due o change in and and vibrations. Ths, transitions 1 bso ses ive eto hp peaks
but peaks are extreme weak The “Ty (G) and “Tag (6) ins ae not pall Sy Hine because
thei energy is ange wih change is igands and thus ransions to thse ses provid road peaks.
Es 1000
gend tá strength (ea)
som 10/00 15000 200 25000 pm as
Wave number (m) —
ES Bet Coccdinaios Chaise
E
Electronic Spectra of d°-Tetrahedral Complexes
Intetahedra! complexes of Ma ions, for examples, (MACI(]”, [MaBra]” the -ocitals split
into e over energy) and (higher energy) ori giving rsetoe? configuration Since tetrehedrl
complexes lack centre of symmetry, therefore, dd transitions are Laporte partly allowed but these
tress are spin forbidden. Therefore, ese transitions interaeckal complexes are weaker However
damon inttabedral complexes are sl stronger than ihigh sin octahedra! complexes because
(0 a transitions are spn forbidden in both tezahodral and high spin octahedral complex (i) dd
rasos are Laporte partly allowed in teahedalcempleses but Lapore forbidden in high spin
cha complees
Racah Parameters and Nephelauxec Serios
Different ters ofa configuration have different energies du o inter-electronic zepulsion. The
ier lie repulsion (or mixing) which causes he bending of the ines is expresse in terms ofthe
Racah parameters Band C which can be calulated from linear conbiatins of coulamb and exchenge
integral. These parameters ae empirical quaniies and are obtained from he spectra of fe ons in gas
pis For the terns of sare spin multipiity, he difference i energy i nly the function of B. For
example, the difference in energy between free ion ground ste term and an excited state tern P of
same mutiplicty for 43,07 and detal ios is 15 B. However, both parameters Band C are
ecssry for tems with diferent milices, fr example, in the Cr (d)ion the difference
etw energy between, *F and 26 is 48 + C For mos aston metal ions value of B ie in the
range of 700-1100 en. Cis equal 9 4B,
The valve of B, labeled as 3° für a complex is always les than tat ofthe rec ion because of
<elocalization of meal letrons in molecular orbitals that encompassbath he meal and ligands. Dueto
‘delocalization of eleszons iner-cletonic repulsion is decreased. The delocalization increases the
sverige septation of electrons and hence reduce hei mata repsan The reduction of B fom is
fice ion val is called nephelauseie effect or cloud expanding effect. The nephslauseic effet is
represented in terms of nephelauxeti parameter (P} which is given by:
Beonper _ B
Errein E
ale iaa nn ve ih ri han ent =
Fora gen met on, value of desresss follows
F > H,0>Nily >en> NCS >Q = CN > BH
This eis i called nep serie.
Loner the valve off, more wll be the delocalization fon and tere wil be significant
covalent charco inthe comple —
Ra etre transitions re observed tente value of can be clic fom he following
equation:
15B" en +v de
Where wave number (in cn") increases inthe onder yj em nz.
CHARGE TRASFER SPECTRA,
Charge transfer transition isthe transfer ofan electron between orbitals that are centred on different
toms. Unlike dd transition, charge transfer transition are Laporte and spin allowed ie,
Al=#1 and 2520 É
“This, charge transfer transitions give rise 10 mor intense (song) absorptions. When these
transitions occur in visible region, the compound show intense colour. A charge transfer transition may
‘be regrded as an intemal redox process. Charge transfer transitions may be classified in four ways
D Ligänd o Metal Charge Transfer (LMCT)
(2) Meal to Ligand Charge Transfer (MLCT)
{G) Inter Valence Charge Teansier
(4) Ina Ligand Charge Transfer
(1) Ligand to Metal Charge Transfer (LMCT)
the transfer of an electron takes place fom the gard to metal, then charge trans is alld ligand
Fo metal charge transfer.
Conditions for LMCT :
(© Metal should be in High oxidation state so that it has high ionization energy, smaller size and
vacant esbitals at low energies.
{i Ligands should have lone par of elecoas of relatively high energy and low electron affinity.
For example, Ia KMoO4, Mn sin +7 oxidaion state and have al the 3d-rbitals vacant. Mn?" ionis
surrounded tetrahedrally by four oxide ions. Al oxide ionshave filed 2p orbitals. There transfer ofan
electron from filled 2p-orbitals of oxide ion 10 vacant dotbitals of Mn/* fon. Since p-orbitals
ungerade and drbtas are gerade, therefore electron transition from prorbiale of O7 ¢o.d-orbitals of
Mo ion is Laporte allowed ie, AL = +! and alo thee is no change in spin mulilicity during
ecronc transition. Therefore, transfer ofan election is Lapon and spn allowed. Therefore, KMnOs
is inteosely purple
Color and cils involved in igand to metal charge transfer of some-compound are given in Table 5,
Enecgy required to transferred at clecton from ligand to metal depend upon the lowest unoccupied
molecular oil (LUMO) ofthe incl catiosTacd e hist occupied molecular orbital (HOMO) of
the god.
Be.
Table 5.5 Colour and Orbials involved ICT of Compounds
TT compound ee
os Yellow Ages (op)
MES Red HE (69 ES” (xp)
Mor Green Mn Bd) co” (mp)
cor Yellow det op)
Kes Red e269) er 6)
V0 Red ren m)
E
Electronic Spectra of d°-Tetrahedral Complexes
Intetahedra! complexes of Ma ions, for examples, (MACI(]”, [MaBra]” the -ocitals split
into e over energy) and (higher energy) ori giving rsetoe? configuration Since tetrehedrl
complexes lack centre of symmetry, therefore, dd transitions are Laporte partly allowed but these
tress are spin forbidden. Therefore, ese transitions interaeckal complexes are weaker However
damon inttabedral complexes are sl stronger than ihigh sin octahedra! complexes because
(0 a transitions are spn forbidden in both tezahodral and high spin octahedral complex (i) dd
rasos are Laporte partly allowed in teahedalcempleses but Lapore forbidden in high spin
cha complees
Racah Parameters and Nephelauxec Serios
Different ters ofa configuration have different energies du o inter-electronic zepulsion. The
ier lie repulsion (or mixing) which causes he bending of the ines is expresse in terms ofthe
Racah parameters Band C which can be calulated from linear conbiatins of coulamb and exchenge
integral. These parameters ae empirical quaniies and are obtained from he spectra of fe ons in gas
pis For the terns of sare spin multipiity, he difference i energy i nly the function of B. For
example, the difference in energy between free ion ground ste term and an excited state tern P of
same mutiplicty for 43,07 and detal ios is 15 B. However, both parameters Band C are
ecssry for tems with diferent milices, fr example, in the Cr (d)ion the difference
etw energy between, *F and 26 is 48 + C For mos aston metal ions value of B ie in the
range of 700-1100 en. Cis equal 9 4B,
The valve of B, labeled as 3° für a complex is always les than tat ofthe rec ion because of
<elocalization of meal letrons in molecular orbitals that encompassbath he meal and ligands. Dueto
‘delocalization of eleszons iner-cletonic repulsion is decreased. The delocalization increases the
sverige septation of electrons and hence reduce hei mata repsan The reduction of B fom is
fice ion val is called nephelauseie effect or cloud expanding effect. The nephslauseic effet is
represented in terms of nephelauxeti parameter (P} which is given by:
Beonper _ B
Errein E
ale iaa nn ve ih ri han ent =
Fora gen met on, value of desresss follows
F > H,0>Nily >en> NCS >Q = CN > BH
This eis i called nep serie.
Loner the valve off, more wll be the delocalization fon and tere wil be significant
covalent charco inthe comple —
Ra etre transitions re observed tente value of can be clic fom he following
equation:
15B" en +v de
Where wave number (in cn") increases inthe onder yj em nz.
CHARGE TRASFER SPECTRA,
Charge transfer transition isthe transfer ofan electron between orbitals that are centred on different
toms. Unlike dd transition, charge transfer transition are Laporte and spin allowed ie,
Al=#1 and 2520 É
“This, charge transfer transitions give rise 10 mor intense (song) absorptions. When these
transitions occur in visible region, the compound show intense colour. A charge transfer transition may
‘be regrded as an intemal redox process. Charge transfer transitions may be classified in four ways
D Ligänd o Metal Charge Transfer (LMCT)
(2) Meal to Ligand Charge Transfer (MLCT)
{G) Inter Valence Charge Teansier
(4) Ina Ligand Charge Transfer
(1) Ligand to Metal Charge Transfer (LMCT)
the transfer of an electron takes place fom the gard to metal, then charge trans is alld ligand
Fo metal charge transfer.
Conditions for LMCT :
(© Metal should be in High oxidation state so that it has high ionization energy, smaller size and
vacant esbitals at low energies.
{i Ligands should have lone par of elecoas of relatively high energy and low electron affinity.
For example, Ia KMoO4, Mn sin +7 oxidaion state and have al the 3d-rbitals vacant. Mn?" ionis
surrounded tetrahedrally by four oxide ions. Al oxide ionshave filed 2p orbitals. There transfer ofan
electron from filled 2p-orbitals of oxide ion 10 vacant dotbitals of Mn/* fon. Since p-orbitals
ungerade and drbtas are gerade, therefore electron transition from prorbiale of O7 ¢o.d-orbitals of
Mo ion is Laporte allowed ie, AL = +! and alo thee is no change in spin mulilicity during
ecronc transition. Therefore, transfer ofan election is Lapon and spn allowed. Therefore, KMnOs
is inteosely purple
Color and cils involved in igand to metal charge transfer of some-compound are given in Table 5,
Enecgy required to transferred at clecton from ligand to metal depend upon the lowest unoccupied
molecular oil (LUMO) ofthe incl catiosTacd e hist occupied molecular orbital (HOMO) of
the god.
Be.
Table 5.5 Colour and Orbials involved ICT of Compounds
TT compound ee
os Yellow Ages (op)
MES Red HE (69 ES” (xp)
Mor Green Mn Bd) co” (mp)
cor Yellow det op)
Kes Red e269) er 6)
V0 Red ren m)
OS
cr Gd) 07 (xp)
Sala Orange Se
Go bight Orange Ben
mao Yalow Poco
[mo - PE) o Gp)
Fe Red Brown .
0 ted
cal Bow =
Dos Redand Yellow nonce oy
Oices ofiron)
Fe(SCN)s Red Le} Gd) SON" (ap)
resp (egy ou or lon tre om goal of don wel inn
clone pc ik VOS CO], and MOO; deste inthe or
vor > 07 >07
On moving fom VOF to GOË to MaOz size of mel cation decrees inthe omer
5* 576% > Min because in this direction effective nuclear charge incesses and energy of acceptor
[nis (ote) deceo. Mere, er o charge tacos ons Hence ney of eye
nee decreases ne flving one
Vo} Go? > Mo; *
hace VOL i colours CO is yellow and Mii pape.
note consequence of he ng difleenc between LUMO ceed on mt anand HOMO
ied on ligands tia heel 13 en bond distance decreases in th order
VO} >C10% > Mog
On moving fom do 441 $4 res fanion meals ina group, a gn ains,
Le of cal fan lts ud cry of LUMO (Le, vaın lal) costed on me elon
caesar cary rulo ante ofan learn kom HOMO font LUMO ot
ato ano ans mess on moving down he grup.
5 #6,
vor or Moog
CACA Increase onder
OL MoO} Te0ÿ of energy of
Gee os inc
Mor Wo} Rg
‘Decreasing order of energy of LMCT
Ter oo anions of 4 and Series transition mals ae colours because cry free
Beten 2p ofende ion and 4d. ad Sabias of rasiton metas very ge nd lern taster
Ron ap a of oxide dial of metal requires high energy vih in UV pion.
In[Cr(NH3)}°* complex ion two d — d bands of lower energy and one bond dueto charge transfer
appar a a sold cn the high energy se of one of the ded ands in UV gin, wie one NH)
gan sele by X” (X =Ch B,D the encgy o vo dd hands and oe huge asx band
decreases becas symme seduced fom Oh to Cay. These bands appear prose ower
nergy ave nab on gang om Clo Bro. Similar specta can be oie {CNHs )5 XT”
on ated!
‘Comper
Figure 55%
(2) Metal to Ligand Charge Transfer (MLCT)
An MLCT, aneleetoa gates from meta to ignad. MLCT ar four in complexes in which
{) Metal ave low oxidation state
Mel chil ao led.
(i) Meta oils ao elatvely high in energy.
{Ligand ave empty wantiboning orbitals
MUCT mainly oc with the ligando having n° orbitals such as CO, CN”, SON”, pycdine,
ny, penalise, prin, ditiline, NO te
cr Gd) 07 (xp)
Sala Orange Se
Go bight Orange Ben
mao Yalow Poco
[mo - PE) o Gp)
Fe Red Brown .
0 ted
cal Bow =
Dos Redand Yellow nonce oy
Oices ofiron)
Fe(SCN)s Red Le} Gd) SON" (ap)
resp (egy ou or lon tre om goal of don wel inn
clone pc ik VOS CO], and MOO; deste inthe or
vor > 07 >07
On moving fom VOF to GOË to MaOz size of mel cation decrees inthe omer
5* 576% > Min because in this direction effective nuclear charge incesses and energy of acceptor
[nis (ote) deceo. Mere, er o charge tacos ons Hence ney of eye
nee decreases ne flving one
Vo} Go? > Mo; *
hace VOL i colours CO is yellow and Mii pape.
note consequence of he ng difleenc between LUMO ceed on mt anand HOMO
ied on ligands tia heel 13 en bond distance decreases in th order
VO} >C10% > Mog
On moving fom do 441 $4 res fanion meals ina group, a gn ains,
Le of cal fan lts ud cry of LUMO (Le, vaın lal) costed on me elon
caesar cary rulo ante ofan learn kom HOMO font LUMO ot
ato ano ans mess on moving down he grup.
5 #6,
vor or Moog
CACA Increase onder
OL MoO} Te0ÿ of energy of
Gee os inc
Mor Wo} Rg
‘Decreasing order of energy of LMCT
Ter oo anions of 4 and Series transition mals ae colours because cry free
Beten 2p ofende ion and 4d. ad Sabias of rasiton metas very ge nd lern taster
Ron ap a of oxide dial of metal requires high energy vih in UV pion.
In[Cr(NH3)}°* complex ion two d — d bands of lower energy and one bond dueto charge transfer
appar a a sold cn the high energy se of one of the ded ands in UV gin, wie one NH)
gan sele by X” (X =Ch B,D the encgy o vo dd hands and oe huge asx band
decreases becas symme seduced fom Oh to Cay. These bands appear prose ower
nergy ave nab on gang om Clo Bro. Similar specta can be oie {CNHs )5 XT”
on ated!
‘Comper
Figure 55%
(2) Metal to Ligand Charge Transfer (MLCT)
An MLCT, aneleetoa gates from meta to ignad. MLCT ar four in complexes in which
{) Metal ave low oxidation state
Mel chil ao led.
(i) Meta oils ao elatvely high in energy.
{Ligand ave empty wantiboning orbitals
MUCT mainly oc with the ligando having n° orbitals such as CO, CN”, SON”, pycdine,
ny, penalise, prin, ditiline, NO te
ee Cosi ao
Ana eher complex wen gander Gion 1 metal) are occupied two MLCT
ands «gg and x? e are observed (revocatoria of the ligand). eter 13 or?
‘orbitals are occupied, then only one charge transfer bond < 4 or * € ez is observed.
“The spectra of Fe (D with ligands containing the dire) unit ave intense charge
wo}
transfer bands caused by the transfer of electron rom metal ng orbitals to x*-orbitals ofthe a-imine
soup.
Fe(ID complexes (C.
to MLCT.
containing tetramine macrocyclic ligand (TIM) have intense colours dee
A
x
‚The compounds and their coloussarsng from MLCT ae shown in Table 5.6
Tables
A
Kaffe)
ON]
[Eaton Po
+27 Ace) Red
(3) Intervalance Transitions (or Metal to Metal Charge Transfer Transitions]_
= these transitions an leon ges xctd fom te valence shell fone lomo valence shelf he
cer atom. Electro transfer takes place fom an to flower kin tat o an another atom of
higher oxidation tae
Forexample
(9 Prusia blue KFe[Fe(CN),] hows intense le colour because of transfer of an electon fam
Fe?" Fe", In Prusian blu, Fe ions cabral cordimated with C atom ofthe
ligands and Fe "¡octal condi with N stom of CN” ligands, Tus, an electron
transfer takes place through bridging yaide ligas,
6) Another example of ntrvalene charge transis Crea Taube on,
LNH )s Ru Pyz- Rony)
he ei lei
se
sous”
In this compound electron transfer acer from Ru) to Ru) through pyeazine bridging
ligand and give intense colour
(ii) Red lead (Pb 0. contains PU and PE(IV). Due o electron transfer from PUD to PLAY),
gives intense rd colour.
(4) intra Ligand Charge Transfer
Some ligands (organic ligands) behave as chromophore and the chromophore nature is responsible
foccolour. There are four electronic transitions —0*, x=, n~R* or =o * within a chonnophare
When suc a ligand is coordinated with metal onto, energy of bsorption changes.
‘Spectra of Compounds with Metal-Metal Bonds
‘he compounds which cons meme bond ie inn clu. Th clr sds to
020 % 7-9 Rand ->5 *inasitoo For example RezCi2 soya blu, MoCLE red, Colour
of compounds having quadruple bonds (ike Rep", MogC If) de to 8 “sancion. The metal
carbonyls conning single M—M bonds ar ofen intel colored due to metal 60 * rasos
Fa cl, (CO igh velo, FeO) bi nO CO) sui
et
TANABE:SUGANO.DIAGRAMS E
Orgel diagrams are useful in be interpretation of spe of spin allowed tras yet asin se)
Gen
interpretation of spectra Of bo high spin and low spin complexes of d? -® metal ins. In Orgel
‘diagrams the ground and excited havesame and maximum maliplicty but in Tanabe Sugano diagrams
"estate of spin multiplicity lower thane ground state areas ince. In Tanabe-Sugano diagrams,
the eos of excited states (expres as 2/8) are plotod gin igund cid strength (exprese as
28018), where B is Racah parameter, a mesure of the repulsion between the Lents of same spin
maple. For example, ford, the energy difference between ?F and Ps 15 B. Because C=~4B,
teas with energies that depend on both and Can be plod on he same diagram. The round ste
(lowest energy sat) i always pleted along the borional axis (abscissa) and the energies of excited
States ae plated relative o the ground tte
Ana eher complex wen gander Gion 1 metal) are occupied two MLCT
ands «gg and x? e are observed (revocatoria of the ligand). eter 13 or?
‘orbitals are occupied, then only one charge transfer bond < 4 or * € ez is observed.
“The spectra of Fe (D with ligands containing the dire) unit ave intense charge
wo}
transfer bands caused by the transfer of electron rom metal ng orbitals to x*-orbitals ofthe a-imine
soup.
Fe(ID complexes (C.
to MLCT.
containing tetramine macrocyclic ligand (TIM) have intense colours dee
A
x
‚The compounds and their coloussarsng from MLCT ae shown in Table 5.6
Tables
A
Kaffe)
ON]
[Eaton Po
+27 Ace) Red
(3) Intervalance Transitions (or Metal to Metal Charge Transfer Transitions]_
= these transitions an leon ges xctd fom te valence shell fone lomo valence shelf he
cer atom. Electro transfer takes place fom an to flower kin tat o an another atom of
higher oxidation tae
Forexample
(9 Prusia blue KFe[Fe(CN),] hows intense le colour because of transfer of an electon fam
Fe?" Fe", In Prusian blu, Fe ions cabral cordimated with C atom ofthe
ligands and Fe "¡octal condi with N stom of CN” ligands, Tus, an electron
transfer takes place through bridging yaide ligas,
6) Another example of ntrvalene charge transis Crea Taube on,
LNH )s Ru Pyz- Rony)
he ei lei
se
sous”
In this compound electron transfer acer from Ru) to Ru) through pyeazine bridging
ligand and give intense colour
(ii) Red lead (Pb 0. contains PU and PE(IV). Due o electron transfer from PUD to PLAY),
gives intense rd colour.
(4) intra Ligand Charge Transfer
Some ligands (organic ligands) behave as chromophore and the chromophore nature is responsible
foccolour. There are four electronic transitions —0*, x=, n~R* or =o * within a chonnophare
When suc a ligand is coordinated with metal onto, energy of bsorption changes.
‘Spectra of Compounds with Metal-Metal Bonds
‘he compounds which cons meme bond ie inn clu. Th clr sds to
020 % 7-9 Rand ->5 *inasitoo For example RezCi2 soya blu, MoCLE red, Colour
of compounds having quadruple bonds (ike Rep", MogC If) de to 8 “sancion. The metal
carbonyls conning single M—M bonds ar ofen intel colored due to metal 60 * rasos
Fa cl, (CO igh velo, FeO) bi nO CO) sui
et
TANABE:SUGANO.DIAGRAMS E
Orgel diagrams are useful in be interpretation of spe of spin allowed tras yet asin se)
Gen
interpretation of spectra Of bo high spin and low spin complexes of d? -® metal ins. In Orgel
‘diagrams the ground and excited havesame and maximum maliplicty but in Tanabe Sugano diagrams
"estate of spin multiplicity lower thane ground state areas ince. In Tanabe-Sugano diagrams,
the eos of excited states (expres as 2/8) are plotod gin igund cid strength (exprese as
28018), where B is Racah parameter, a mesure of the repulsion between the Lents of same spin
maple. For example, ford, the energy difference between ?F and Ps 15 B. Because C=~4B,
teas with energies that depend on both and Can be plod on he same diagram. The round ste
(lowest energy sat) i always pleted along the borional axis (abscissa) and the energies of excited
States ae plated relative o the ground tte
iii pS
SA
For different is-cetonie ins (ame eecronie configuration) like TE and V"* with 42
configuration the values of Bae diferent. Aste velo of depends upon ligand field reg),
therfore, by ploting E agains A/B. One Tanabe Sugano diagram may be used for diferen:
jso-letronic metal ions. When the ge field strength increases, he lines of same symmetry aver
Gross each other br bent far apart ram each ker du toning (repulsion) of tems. This is called non
crossing rule.
Calculation of A, and B using Tanabe-Sugano diagrams
() ATS diagram for d?-octabedral complexes is shown in Figure 5.54. Note that there is no
Fundamental diffrence betwee weak and ston fed. The T-S diagrams ofd?, a? anda axe
simplified by showing only the energy levels of the states of maximum spin muti
‘because these are involved in observable spectral bands,
wo we aD
Electronic spectra of V(H:0}6}"* ion show two bands corresponding tothe transitions,
See ME) ¢ = 17200em™
rede Mel) 59-200!
‘The third band is of high energy and weak intensity because oft electrons transition.
The ratio of these energies is given by
EX £218" 25100
FBI 17200
ing a ruler along the abscissa in Figure 5.54
pre
votaste, EA sors, 12-28 Acie pio Belt / 2°
and Ez /B' are 26 and 39 respectively. Ths,
Value oF cn ob ett fon
22510, y
Pe
“659 em"!
Plo i it yt eo E cmap 8s
tina ea 5
Theos,
e,
‘The value PA, = 28% 659 = 18452 em
() T.S diagrams for dand d® octahedral complexes:
The TS diagrams for d? snd a actaeial complexes ar same but these die in he spin
= multiplicity of the tenn symbol usaf, fr example, [CH(H10)J°* and {Ni(HjO)6)?". In these
cases A can also obtined by measuring lowes energy transition, y
‘The TS diagram ford? anda acabes complexes are shown in Figure 5.550) nd 5550)
‘The electronic spectrum of Cr(H:0}¢}™ shows three transitions :
Mg © ag, E
Tig (FY © Slag, By = 1450000"
“Tig PIE ag, Es =¥5 =378000n
Teeth band ase as «solder due toprsenge of change transfer asin. Tera» andy
is given by:
122 End st
mB Bye" O
SA
For different is-cetonie ins (ame eecronie configuration) like TE and V"* with 42
configuration the values of Bae diferent. Aste velo of depends upon ligand field reg),
therfore, by ploting E agains A/B. One Tanabe Sugano diagram may be used for diferen:
jso-letronic metal ions. When the ge field strength increases, he lines of same symmetry aver
Gross each other br bent far apart ram each ker du toning (repulsion) of tems. This is called non
crossing rule.
Calculation of A, and B using Tanabe-Sugano diagrams
() ATS diagram for d?-octabedral complexes is shown in Figure 5.54. Note that there is no
Fundamental diffrence betwee weak and ston fed. The T-S diagrams ofd?, a? anda axe
simplified by showing only the energy levels of the states of maximum spin muti
‘because these are involved in observable spectral bands,
wo we aD
Electronic spectra of V(H:0}6}"* ion show two bands corresponding tothe transitions,
See ME) ¢ = 17200em™
rede Mel) 59-200!
‘The third band is of high energy and weak intensity because oft electrons transition.
The ratio of these energies is given by
EX £218" 25100
FBI 17200
ing a ruler along the abscissa in Figure 5.54
pre
votaste, EA sors, 12-28 Acie pio Belt / 2°
and Ez /B' are 26 and 39 respectively. Ths,
Value oF cn ob ett fon
22510, y
Pe
“659 em"!
Plo i it yt eo E cmap 8s
tina ea 5
Theos,
e,
‘The value PA, = 28% 659 = 18452 em
() T.S diagrams for dand d® octahedral complexes:
The TS diagrams for d? snd a actaeial complexes ar same but these die in he spin
= multiplicity of the tenn symbol usaf, fr example, [CH(H10)J°* and {Ni(HjO)6)?". In these
cases A can also obtined by measuring lowes energy transition, y
‘The TS diagram ford? anda acabes complexes are shown in Figure 5.550) nd 5550)
‘The electronic spectrum of Cr(H:0}¢}™ shows three transitions :
Mg © ag, E
Tig (FY © Slag, By = 1450000"
“Tig PIE ag, Es =¥5 =378000n
Teeth band ase as «solder due toprsenge of change transfer asin. Tera» andy
is given by:
122 End st
mB Bye" O
SS O
‘The electronic spectrum of [Ni(H20)« + complex ion shows three electron transitions
Ss, «68 ” ar, de ag © Bags En = 11 = 8800 em
5 Sel) E ag; Er =p = 14500 cm
> Pr 7) + PE B=
5 “, so . Them kr, edge
| do | 7 aya AE
go vw Ez
fr » By sig ur along he abc in Figure 5.55).
Tneratio Fs obtained a Le
a 2218
Atti pint E58" 228
»
ET] ch es
* Ad 59 2 30 4
oo » à
a ae Sine
© e 7
Treo,
i Eu
Now tom Figure SS, by ing ale along he bein he ato ney a
Since
a A,
For caution of id transition to “Tig (P), the value of Ey” comesponding to FF
obtained equal 54.
Thus,
{Fall dhe thre transitions are posible then value of 3’ can alo be calculated by +
5B" = v5 +v 3 =37800-+24500~3>17400
&'=675em
Tanabe-Sugano Diagram for d°-Octahedral Complexes
The TS diagram afd octahedral complexes (high spin and low sini shown in Figure 5.56.
‘The fice ion ground state farCo** (d% )is 5D and there are various high energy states out of which,
1, important. In othe field $D splits into Ta (ground state) nd “Excited state) and Y
pli no fie diferent ates out of whic the ys important. is o benoted tht ground state of
Biggi (fiche ap degenerate with spin mld ote, Tag and th pound
si fr tow si) a gate wh spin mic oli A
Aste ind ieldtrengin (8 „Jinreaes "Ag excited state oftighspin comple ills rapidly and
positions eachedatwhich le becomes ground state. At this postion the ping afectos takes
place ea this position be HS complex just stats to change in LS complex esultinginadiscontimuty
inthe TS diagram. Therefore, his point is called high spin- tow spin cs ove pois. This cross over
pain bsos = Panda vecino eos ave igh pin
complex odo he ight e have low spin complex
‘The electronic spectrum of [Ni(H20)« + complex ion shows three electron transitions
Ss, «68 ” ar, de ag © Bags En = 11 = 8800 em
5 Sel) E ag; Er =p = 14500 cm
> Pr 7) + PE B=
5 “, so . Them kr, edge
| do | 7 aya AE
go vw Ez
fr » By sig ur along he abc in Figure 5.55).
Tneratio Fs obtained a Le
a 2218
Atti pint E58" 228
»
ET] ch es
* Ad 59 2 30 4
oo » à
a ae Sine
© e 7
Treo,
i Eu
Now tom Figure SS, by ing ale along he bein he ato ney a
Since
a A,
For caution of id transition to “Tig (P), the value of Ey” comesponding to FF
obtained equal 54.
Thus,
{Fall dhe thre transitions are posible then value of 3’ can alo be calculated by +
5B" = v5 +v 3 =37800-+24500~3>17400
&'=675em
Tanabe-Sugano Diagram for d°-Octahedral Complexes
The TS diagram afd octahedral complexes (high spin and low sini shown in Figure 5.56.
‘The fice ion ground state farCo** (d% )is 5D and there are various high energy states out of which,
1, important. In othe field $D splits into Ta (ground state) nd “Excited state) and Y
pli no fie diferent ates out of whic the ys important. is o benoted tht ground state of
Biggi (fiche ap degenerate with spin mld ote, Tag and th pound
si fr tow si) a gate wh spin mic oli A
Aste ind ieldtrengin (8 „Jinreaes "Ag excited state oftighspin comple ills rapidly and
positions eachedatwhich le becomes ground state. At this postion the ping afectos takes
place ea this position be HS complex just stats to change in LS complex esultinginadiscontimuty
inthe TS diagram. Therefore, his point is called high spin- tow spin cs ove pois. This cross over
pain bsos = Panda vecino eos ave igh pin
complex odo he ight e have low spin complex
SESSA AN5559
Forlowspincompens, the ground sat Ais taken asthe abc href, eight hand part
the TS diagram seda
‘The eecronie spectrum of igh spn -ciahdral complex stows ony ane eet tension
Ey € Tag and it gives the direct measure of A,. For example, [CoF]” complex ion is blue
are nd only oe eectonictanstion “Ez € Ta oct at 13100 cu”. Therefore Ay forte
nlx io is 13100 en
The icone pet low pin Co * complexes show to rn allowed asnos ig "ig
ie & Mig (shown on ight of TS dira), There ae some ote pi aloe aston but
ese ace of higher energies, These ace masked by charge transfer trains and, therefore, ace not
served,
For example, an electronic spectrum of iow spin complex, [Cofen); ]°* shows two bands at 21500
1"! and 29500 om? conesponding to the transitions:
Mg + Migs Ei =m =21500 em"
Mag © igi Br =¥2
Now
Es EN
EL EB
21500
A,
Now Som Figure 556, by sliding rule along horizontal axis, this ratio is obtained at 24 = 40. a
Also, since
Ths,
Tanabe-Sugano Diagram tor d*-octahedral Complexes
TS diagram far d'-cthodral complenes is shown in Fe 57.
‘The free ion ground state term for d*-configuration is * D'and there are various excited states out of
‘which PH is important In octahedral complexes * D term pls ino SE, Gower energy) and 73e
Chigherenegy) and > state splits into two Tip, Ÿ E and Tay states ntofwhich 7 state oflower
cacy impo. sone pi be ot oud ignore
degenerate wit gin pict of Le, 5, and te ond ut flow income (ei
teply degenerate wit spin multiplicty of 3, ie, "Zig.
Forlowspincompens, the ground sat Ais taken asthe abc href, eight hand part
the TS diagram seda
‘The eecronie spectrum of igh spn -ciahdral complex stows ony ane eet tension
Ey € Tag and it gives the direct measure of A,. For example, [CoF]” complex ion is blue
are nd only oe eectonictanstion “Ez € Ta oct at 13100 cu”. Therefore Ay forte
nlx io is 13100 en
The icone pet low pin Co * complexes show to rn allowed asnos ig "ig
ie & Mig (shown on ight of TS dira), There ae some ote pi aloe aston but
ese ace of higher energies, These ace masked by charge transfer trains and, therefore, ace not
served,
For example, an electronic spectrum of iow spin complex, [Cofen); ]°* shows two bands at 21500
1"! and 29500 om? conesponding to the transitions:
Mg + Migs Ei =m =21500 em"
Mag © igi Br =¥2
Now
Es EN
EL EB
21500
A,
Now Som Figure 556, by sliding rule along horizontal axis, this ratio is obtained at 24 = 40. a
Also, since
Ths,
Tanabe-Sugano Diagram tor d*-octahedral Complexes
TS diagram far d'-cthodral complenes is shown in Fe 57.
‘The free ion ground state term for d*-configuration is * D'and there are various excited states out of
‘which PH is important In octahedral complexes * D term pls ino SE, Gower energy) and 73e
Chigherenegy) and > state splits into two Tip, Ÿ E and Tay states ntofwhich 7 state oflower
cacy impo. sone pi be ot oud ignore
degenerate wit gin pict of Le, 5, and te ond ut flow income (ei
teply degenerate wit spin multiplicty of 3, ie, "Zig.
Coin Cheat
Aste ligand feld strength increases, he À Ti, (derived om À H site) excited state of high spin
complex fills rapidly and 2 position is obtained where pairing of electrons takes place and now the
ground state becomes * Tig. This point observed at 2 =27is indicated by a vertical line. To the left of
this point we have high pin complex and to the right we have low spin complex. The singlet states and
higher ile states are omited from the simpliña digram They have no relevance o the observed
spectra ofcompleses. In low spin complexes "Tay <= *Tig and FT, <= Tg transitions are observed,
T-S Diagram for d7-Octahedral Complexes.
‘TS diageam for d? -octahedeal complexes is shown in Figure 5.58.
‘The fie ion ground state for d”-configuration is * and one excited state of same multiplicity is
and one of he other excited states is 2G which is important In octahedral field * term splits into “Zig,
og and * dag ters. * P term does not split but transfoons into is (P) term. *Tig isthe ground
state. 2G term splits into four different states out of which “E, is important, For high spin complexes
the round tate tems “Tig (¢,¢2)and for low spin compe the ground stats tenis 2, (6, e)
Inthe d7-T-S diagram the 7B state derived from 7G decreases in energy rapidly as ligand field
strength increases and position is reached where pairing of elecrons occur. This position is obtained
stg! B' = 22 At this point HS and LS complexes remain in quilibriom.
To the right side of the vertical fine of the Figure 5.8 the complex becomes a low spin and the
ground state becomes ? 8. Now the” statis takea on horizontal in. After spin cross over point,
with increase in ligand field strength, the energy of “Ti increases as am excited state,
‘The spinallowed transition ford? low spin complexesre
anew ie,
Ty E,
Mag Es
and ? Aig «DE, (at much higher energy tobe observed)
‘The eecronie spectrum of (CoFg]* shows thre electron tastions
early te same energy
Mag E Tig 5 Biz =7150em*
Mag E Te: Ez =m) =152000n*
IS
mie ER
me a EB
= 1495 m"
For low spin complexes of Co** ion like [Co(NH3)¢}°*, [Co(en)3 }°* , [Co(ox)3)”" the ground
sate comepntig tothe ef coniguton represents
BAR
wien oc ofthe lens om $, is excited ul e lero configuaon becomes
Therese vo singlet sates Ti an Ta compet te confusion
IT sate cam be represented by any ofthe treo ways:
per
yde,
Ga dd,
da
End,
Aste ligand feld strength increases, he À Ti, (derived om À H site) excited state of high spin
complex fills rapidly and 2 position is obtained where pairing of electrons takes place and now the
ground state becomes * Tig. This point observed at 2 =27is indicated by a vertical line. To the left of
this point we have high pin complex and to the right we have low spin complex. The singlet states and
higher ile states are omited from the simpliña digram They have no relevance o the observed
spectra ofcompleses. In low spin complexes "Tay <= *Tig and FT, <= Tg transitions are observed,
T-S Diagram for d7-Octahedral Complexes.
‘TS diageam for d? -octahedeal complexes is shown in Figure 5.58.
‘The fie ion ground state for d”-configuration is * and one excited state of same multiplicity is
and one of he other excited states is 2G which is important In octahedral field * term splits into “Zig,
og and * dag ters. * P term does not split but transfoons into is (P) term. *Tig isthe ground
state. 2G term splits into four different states out of which “E, is important, For high spin complexes
the round tate tems “Tig (¢,¢2)and for low spin compe the ground stats tenis 2, (6, e)
Inthe d7-T-S diagram the 7B state derived from 7G decreases in energy rapidly as ligand field
strength increases and position is reached where pairing of elecrons occur. This position is obtained
stg! B' = 22 At this point HS and LS complexes remain in quilibriom.
To the right side of the vertical fine of the Figure 5.8 the complex becomes a low spin and the
ground state becomes ? 8. Now the” statis takea on horizontal in. After spin cross over point,
with increase in ligand field strength, the energy of “Ti increases as am excited state,
‘The spinallowed transition ford? low spin complexesre
anew ie,
Ty E,
Mag Es
and ? Aig «DE, (at much higher energy tobe observed)
‘The eecronie spectrum of (CoFg]* shows thre electron tastions
early te same energy
Mag E Tig 5 Biz =7150em*
Mag E Te: Ez =m) =152000n*
IS
mie ER
me a EB
= 1495 m"
For low spin complexes of Co** ion like [Co(NH3)¢}°*, [Co(en)3 }°* , [Co(ox)3)”" the ground
sate comepntig tothe ef coniguton represents
BAR
wien oc ofthe lens om $, is excited ul e lero configuaon becomes
Therese vo singlet sates Ti an Ta compet te confusion
IT sate cam be represented by any ofthe treo ways:
per
yde,
Ga dd,
da
End,
‘yg state can be represented by any ofthe tree ways
de die dis
2 4 ad
éd dde;
2 a dd
Gadd,
‘The energy of Tig state is lower because in bis State the fay ole ib as close as posible e
«econ. In gener the following spin lowed transito are possible
ge Nig
Mg e Mig 7
ranstons 0 higher singlet states 8 and 4 comesponding o 4, e and, ef configurations
ae of extremely high energy and ar ull not observed.
“The colour ofeisand rans-somers of complexes (Col. Y] or [Co + 1)2 X2 frequently dite.
Because (lke etrahedral complex) is same as cere o symmetry, its bands in spectrum ae
more intense than those of centosymmetic ansisomer. For example, the cisisomer of
{CofenCls]* is volet whereas the ans isomeris bright green.
In[CoL4X]* or{Co(L-L)2X2¥" complex the syrametry is lowered and the "Ti and 'Tyy states
ae spit. The trans isomer wll sl the excited states mare than the civisomer.Splitng of lowest
nit state (Tg) is more approche tan the ober excited states. Ifthe two diferent ligands (eg.
L-L=enand.X=F) differ appreciably in ld steagth the hands split completely giving rst thee
separate bands for otras isomer whereas the is isomer commonly show no diia ping and
show slight symmetry in the lower energy band.
‘When the to wee ligands ar rans o nc another on z-axis, they interact with oly d,z-ortitl
andthe effective feld strength along anis th average ofthe field strengths ofthe two liga. tbe
«ivisomerthe weak ligand arco one another inay-plan and two ofthe fur strong ligas are ans
40 one another along the z-axis. The spliting of Ti, state depends on the differences between the
strength of ligands on ars and in sy pao and ths the pl
complex.
1 of trans complex is twice ofthe cis
‘T-S Diagram for d° octahedral Complexes
“TS diagram for d°-oenhedrl compleses is sown in Figure 5.59.
The fe in ground state term fora configuration is À and there are various excited states of
fern spin maps of bichon import. In other el te docs opt
but transforms into © Ay, but 2 team splits into five excited states out of which only 27, is important
Ground state term for high pin comple is Ay (he and ground state term of low spin compleris
ag (44)
As the ligand field strength increases, he energy of 273, (derived from 21) als rapidly and a
position is reached where ?Ta, state becoms ground sate At this point A/B" =28 and pairing of
electrons occurs and to right side ofthe diagram complex becomes low spin.
After spin crossover point with increase ligand fel strength th energy of © Ay increases avan
excited state
Calculation of à from Spectra
1. Foral, d*, d® and d? octahedral and tetrahedral complexes, there is only one electronic transition
and ithas energy equal tog ory.
2. For d?,d°,d7 and d high spin otabodral and tetrahedral complexes thee transitions are
possible. The magnitode of is equal tothe energy ofthe lowest transition ofthe thre which are
observable ford and dS configuration. à ford sad d? configuration is the difference in energy
between te fst and third transitions. In other words, isthe energy difference between adjacent
Ang and Tag terms,
de die dis
2 4 ad
éd dde;
2 a dd
Gadd,
‘The energy of Tig state is lower because in bis State the fay ole ib as close as posible e
«econ. In gener the following spin lowed transito are possible
ge Nig
Mg e Mig 7
ranstons 0 higher singlet states 8 and 4 comesponding o 4, e and, ef configurations
ae of extremely high energy and ar ull not observed.
“The colour ofeisand rans-somers of complexes (Col. Y] or [Co + 1)2 X2 frequently dite.
Because (lke etrahedral complex) is same as cere o symmetry, its bands in spectrum ae
more intense than those of centosymmetic ansisomer. For example, the cisisomer of
{CofenCls]* is volet whereas the ans isomeris bright green.
In[CoL4X]* or{Co(L-L)2X2¥" complex the syrametry is lowered and the "Ti and 'Tyy states
ae spit. The trans isomer wll sl the excited states mare than the civisomer.Splitng of lowest
nit state (Tg) is more approche tan the ober excited states. Ifthe two diferent ligands (eg.
L-L=enand.X=F) differ appreciably in ld steagth the hands split completely giving rst thee
separate bands for otras isomer whereas the is isomer commonly show no diia ping and
show slight symmetry in the lower energy band.
‘When the to wee ligands ar rans o nc another on z-axis, they interact with oly d,z-ortitl
andthe effective feld strength along anis th average ofthe field strengths ofthe two liga. tbe
«ivisomerthe weak ligand arco one another inay-plan and two ofthe fur strong ligas are ans
40 one another along the z-axis. The spliting of Ti, state depends on the differences between the
strength of ligands on ars and in sy pao and ths the pl
complex.
1 of trans complex is twice ofthe cis
‘T-S Diagram for d° octahedral Complexes
“TS diagram for d°-oenhedrl compleses is sown in Figure 5.59.
The fe in ground state term fora configuration is À and there are various excited states of
fern spin maps of bichon import. In other el te docs opt
but transforms into © Ay, but 2 team splits into five excited states out of which only 27, is important
Ground state term for high pin comple is Ay (he and ground state term of low spin compleris
ag (44)
As the ligand field strength increases, he energy of 273, (derived from 21) als rapidly and a
position is reached where ?Ta, state becoms ground sate At this point A/B" =28 and pairing of
electrons occurs and to right side ofthe diagram complex becomes low spin.
After spin crossover point with increase ligand fel strength th energy of © Ay increases avan
excited state
Calculation of à from Spectra
1. Foral, d*, d® and d? octahedral and tetrahedral complexes, there is only one electronic transition
and ithas energy equal tog ory.
2. For d?,d°,d7 and d high spin otabodral and tetrahedral complexes thee transitions are
possible. The magnitode of is equal tothe energy ofthe lowest transition ofthe thre which are
observable ford and dS configuration. à ford sad d? configuration is the difference in energy
between te fst and third transitions. In other words, isthe energy difference between adjacent
Ang and Tag terms,
1. A compound shor the radiation of ed colour The colour fe com un
2. The broad and unsymmetrical band inthe absorption spectrum of Ti(H0)q} ismainly due to
3. The intensity of colour of CaCI is. than that of {Co(HO)
A. The intense red olor of demyhemaglobin due to... ML ET
5. The electron transfer in LMT iS Lap and pi …
6. Cul forms int pink eure complex wi -phenantroline. When his complex is aduce,
the colour ofthis compound isppeas, The colour of his compound sde to
7. The comples (CO O) So oc and
8. Number of miorosttes for V°* (@*-configuration} is
9. Lowest energy sat fo [VEN jg * is
10, Lowest energy state (CONS is
AL. The Be lou o£(COCAyP” 844610 ac and sass
12. The complex TC, absorbs at 13000 cm, The value o, is
13. Th intense colourofKFe{C(CN),}is de o
14. The complimentary colour ofornge is …
15, Ground state for(Co(CN)6]”” i electronically
16, The lowest energy electronic transition for [Ni(RH3 61° is
17. The intense ble colour of RezCg is to.
me ee: nas
ya
19. The complex FC)?" isenouess because it .
20, The complex (CNE: JE" hass Val... than CN)”
{ns 1. green 2. Jahn-Tellerdistonion YA
Pe. cater 8
5. allved, allowed 6. de anston Ys
7. high spin, paramagnetic, coloured 8. 45 49
3 4 Be)
9. ig 10. og =
11. some pd mixing, spin allowed
12. 13000 emt
13. inter valence charge transfer, Le, Fe?* 10 Cr?"
14. blue 15. non-degenerate
16. tag ag 17, § 95 * transition
18.3 19, absorbs in IR region
20. higher]
1. For which one oft following ons, he colour is NOT dueto a dd transition?
@) ao _— GONE)"
Tao GE
2. Which one of he fllowing complex ions shows the minimum intensity of absorption inthe
UV visible region?
COURS OO
OO OO
3. The ground state pf V?* ion is
CHA ©) 520
(oF Ds
y comple which exhibits ouest exergy eletonic absorption bend is
(nicl 7 DIOR
ONC (8) Ni(CO)e
5. The orange colour of C07 is duct:
(4) meta ligand charge taster tension
Dé to et charge tantes tati
(Cc) erystal-field transi
___ (4) charge-transfer complex formation
% ‘The dark purple color OK MAO i due to
(a) de ensiton (6) ligand fel transition
(e) charge transfer transition (Yo - x" transition
he absorption of Co(NH3)2* is
(a) stronger than that of (Co(NE sa? Ta 57
(0) cong ban that MOI u
(6) weaker than that offMnC1, > but stronger than that oFFCOLNK;)sCH?"
(@ weaker than those of both MaClg] and [Co(NH3)5C1P*
2. The broad and unsymmetrical band inthe absorption spectrum of Ti(H0)q} ismainly due to
3. The intensity of colour of CaCI is. than that of {Co(HO)
A. The intense red olor of demyhemaglobin due to... ML ET
5. The electron transfer in LMT iS Lap and pi …
6. Cul forms int pink eure complex wi -phenantroline. When his complex is aduce,
the colour ofthis compound isppeas, The colour of his compound sde to
7. The comples (CO O) So oc and
8. Number of miorosttes for V°* (@*-configuration} is
9. Lowest energy sat fo [VEN jg * is
10, Lowest energy state (CONS is
AL. The Be lou o£(COCAyP” 844610 ac and sass
12. The complex TC, absorbs at 13000 cm, The value o, is
13. Th intense colourofKFe{C(CN),}is de o
14. The complimentary colour ofornge is …
15, Ground state for(Co(CN)6]”” i electronically
16, The lowest energy electronic transition for [Ni(RH3 61° is
17. The intense ble colour of RezCg is to.
me ee: nas
ya
19. The complex FC)?" isenouess because it .
20, The complex (CNE: JE" hass Val... than CN)”
{ns 1. green 2. Jahn-Tellerdistonion YA
Pe. cater 8
5. allved, allowed 6. de anston Ys
7. high spin, paramagnetic, coloured 8. 45 49
3 4 Be)
9. ig 10. og =
11. some pd mixing, spin allowed
12. 13000 emt
13. inter valence charge transfer, Le, Fe?* 10 Cr?"
14. blue 15. non-degenerate
16. tag ag 17, § 95 * transition
18.3 19, absorbs in IR region
20. higher]
1. For which one oft following ons, he colour is NOT dueto a dd transition?
@) ao _— GONE)"
Tao GE
2. Which one of he fllowing complex ions shows the minimum intensity of absorption inthe
UV visible region?
COURS OO
OO OO
3. The ground state pf V?* ion is
CHA ©) 520
(oF Ds
y comple which exhibits ouest exergy eletonic absorption bend is
(nicl 7 DIOR
ONC (8) Ni(CO)e
5. The orange colour of C07 is duct:
(4) meta ligand charge taster tension
Dé to et charge tantes tati
(Cc) erystal-field transi
___ (4) charge-transfer complex formation
% ‘The dark purple color OK MAO i due to
(a) de ensiton (6) ligand fel transition
(e) charge transfer transition (Yo - x" transition
he absorption of Co(NH3)2* is
(a) stronger than that of (Co(NE sa? Ta 57
(0) cong ban that MOI u
(6) weaker than that offMnC1, > but stronger than that oFFCOLNK;)sCH?"
(@ weaker than those of both MaClg] and [Co(NH3)5C1P*
maa
8. The ground sate term symbols for high spin d55 and d°-configuation, respectively, are;
| (9) Sana és (0) Pend 3s
"Sand SY (@) ?P and és
| Co permet tose
(Laa oe
[osa (Osma
| 10. The number of possible d«d transitions in Cu(NH5J * vb
(one (Quo
| Ag tree @ tour
KE fe compan wie shows LM charge tasers
Gr NICO), 7 ©) K ¿01207
(6) Hgo. NEO)
12, The spectroscopic ground state symbol and the total number of electronic transitions of
ES
@ Tg and2 (0) * ag and3
| (©) Tig and3 / 10) * Ag and 2
1((13} wise of the following setahedrat complexes shows Mag > Ang masitin as the lowest
energy visible band in its electronic spectrum ? -
CUS OS
(©)[Co(NHS 6} NEO
| 24 Ruby has low concentration of valent 34 él btt or A in alumia giving
initial excitations ofthe spin-allowed processes "Thy <= Ang and “Thy €-*43g. The 3d-metal
17. The ground ie tem symbol of Ni? ion is
(3 & 4
oP GE
| ions: at 3
| Ben Y (o) Fe(ttiy f w a
€) Caf nian) Lise
he compound hat absorks light of fongest wavelength is RW) og
CENTS DEE
| Or CES
16, Which ofthe following compound, shows inter valence che transfer aston?
(a) P30, (9) KC1207
| CLOSE (6) Mnz(CONo
18. The bright yellow colour of {Cu(phen) ]* (phen = 1,10- phenanthrofine) is due to :
(o) detentions
(0 meta to ligand ehrage transfer
(© ligand 0 metal charge transfer
(9) zo" transition in the phenanthroline ligand
19. The pe colour of Mal H0)3" is due to:
(9 pin bien dd tanition (6) metal igand change transfer
© land metal charge transfer (inte ligan excision
20, The aber of dd electronic bands in spectra forte high-spin Fe) ctahedral system is:
ami (6) two.
Oki (one >
A. The ground state term for 1, in octahedral Fld is: ae 3
Wa 7 DE 2
CEA CE -
22) Which one ofthe following electronic configuration of an octabedl metal complex will show
three spin allowed elocmonic transitions? :
A hy og, 7
“one wae,
128, Then ofthe yellow colour ofa aqueous solution of K3C104 is to:
(a) dd'raisition (9) H20 10 Ce charge transfer
(0107 to K* charge transfer 440°" (0 Cr charge transfer
8) The mala absorptivity ath po i imum foc
MOO} MALO"
AP oo. FAME
23, Only oñe absorption band is observed in visible region of spectrum of :
GLAM yf gO (TIE! a!
OH # © vor
26. The Jost energy dr waitin in the CD) complexes vais inthe ode:
SCA < Ct 0)3* < Gren) $"< CCN)
(AC fent < HO)? < OCDE
(CUCM << Cto)" < Ce}
ao)! < en)! < CE «can!
8. The ground sate term symbols for high spin d55 and d°-configuation, respectively, are;
| (9) Sana és (0) Pend 3s
"Sand SY (@) ?P and és
| Co permet tose
(Laa oe
[osa (Osma
| 10. The number of possible d«d transitions in Cu(NH5J * vb
(one (Quo
| Ag tree @ tour
KE fe compan wie shows LM charge tasers
Gr NICO), 7 ©) K ¿01207
(6) Hgo. NEO)
12, The spectroscopic ground state symbol and the total number of electronic transitions of
ES
@ Tg and2 (0) * ag and3
| (©) Tig and3 / 10) * Ag and 2
1((13} wise of the following setahedrat complexes shows Mag > Ang masitin as the lowest
energy visible band in its electronic spectrum ? -
CUS OS
(©)[Co(NHS 6} NEO
| 24 Ruby has low concentration of valent 34 él btt or A in alumia giving
initial excitations ofthe spin-allowed processes "Thy <= Ang and “Thy €-*43g. The 3d-metal
17. The ground ie tem symbol of Ni? ion is
(3 & 4
oP GE
| ions: at 3
| Ben Y (o) Fe(ttiy f w a
€) Caf nian) Lise
he compound hat absorks light of fongest wavelength is RW) og
CENTS DEE
| Or CES
16, Which ofthe following compound, shows inter valence che transfer aston?
(a) P30, (9) KC1207
| CLOSE (6) Mnz(CONo
18. The bright yellow colour of {Cu(phen) ]* (phen = 1,10- phenanthrofine) is due to :
(o) detentions
(0 meta to ligand ehrage transfer
(© ligand 0 metal charge transfer
(9) zo" transition in the phenanthroline ligand
19. The pe colour of Mal H0)3" is due to:
(9 pin bien dd tanition (6) metal igand change transfer
© land metal charge transfer (inte ligan excision
20, The aber of dd electronic bands in spectra forte high-spin Fe) ctahedral system is:
ami (6) two.
Oki (one >
A. The ground state term for 1, in octahedral Fld is: ae 3
Wa 7 DE 2
CEA CE -
22) Which one ofthe following electronic configuration of an octabedl metal complex will show
three spin allowed elocmonic transitions? :
A hy og, 7
“one wae,
128, Then ofthe yellow colour ofa aqueous solution of K3C104 is to:
(a) dd'raisition (9) H20 10 Ce charge transfer
(0107 to K* charge transfer 440°" (0 Cr charge transfer
8) The mala absorptivity ath po i imum foc
MOO} MALO"
AP oo. FAME
23, Only oñe absorption band is observed in visible region of spectrum of :
GLAM yf gO (TIE! a!
OH # © vor
26. The Jost energy dr waitin in the CD) complexes vais inthe ode:
SCA < Ct 0)3* < Gren) $"< CCN)
(AC fent < HO)? < OCDE
(CUCM << Cto)" < Ce}
ao)! < en)! < CE «can!
Se
27. The term symbol forthe ground state ofehodium (Rh, atomic number 45) is ŸF. The electronic
configuration for this term symbol is
4) (Kel 4475 Es?
OR Mr ssp!
28. The red colour of oxyhemoglobín is manly dueto e
GG 4d tansition
(b) metal to ligand charge transfer transition
(© ligand to metal charge taser nica
(4) intra ligand x- x" transition
@ ye crystal field stabilization energy (CESE) value für FIi(H¿0)6]?* that has an absorption
rm at 492 nm is +
N (0) 20325 om! (9 1219500!
(©) 10,162 cm“! @8,1300m =
@ Inthe io-learonie series VO} CAO" and MO, a member ta nese charge ns
(N transitions. The incorrect statement is:
As @)CT transition ar attribute o excitations of electrons fom igand (9) o metal ()
(0) MO; exhibit charge transfer at shore wavelength among the three
(6) The waveengis of transions nema in ie rer VO} < CO < MO
(& The charge on metal mues increase in he oder VO} =O? < Maz
31. The increasing order of wavelength of absorption forthe complex ions
DICH" (i) (OC GÜDLCHOR)]* GWICHENIT” is
(@ivciiciciit @ivcireici
(icicióci > (Oi<i<icin
32. The comect order OFLMCT ee is:
(a) Mn; <a} < vor €) M10% > GO} > vor
onset >} <VOr (4) Ma0z < GO} > vor
(62 ie grand ste of igh pin otal ada Ot complexe ae respective
io! Tag and * Ay © Ty and Ay
Tig andy CRT
34. The complex that absorbs light of shortest wavelength is
de) {Core™
VO
OR
OK PX = OF)
electronic spectrum of (CrFs]” shows three bands at 14,900 cra”, 22,400 cm * and 34,800
em. The value of Ag inthis case it
(05500 cmt 6) 149000! 7
Q2400en* (Aa
(Tie number o spin allowed and el anton fo octahedral GU) complex wth oy
rod siti:
I om Wine
> Cone iur
31. Te number of miete for decom configuration is
axe wie
One 00
Te is excited state configunsin fr low pinocaheda system is:
pe on - -
7 OES OR Lei os a2
MoO} jon hors at 22000 er and 35000 em in, UV-visible Absorption spectrum. The
vale of y is
A ac ON
OEM (@6500en"*
£48) Addition of an aqueous solution of Fell) t potassium hexacyanochromate(I) pioduces a
‘rik-red colored comple, wich tums dark gen at [00"C, The dark green complex is:
@)FealCAN)s]s OOO
OKCHEECNE] FLAC)
41. The ground state term (NO) D is
(0) Te CE
Or CEA ce
42) An ion M?* forms the complexes [M(HL0)6 7", (M(ea)3}* and [.MBrs]?", match the
complex with appropriate colour: ,
@ gen blue and ed (0) bu, red and green
un red and blog (@red, blue and green
blue colour of Prussian ble isa esl of
(a) electron transfer between Fe(it) and Fe()
(9) electron transfer between Fe) and Fe(II}
(@ddtaansition £
(8) paramagnetic nature of Fe) end a.
MS y
an
vf gan?
00%
0: NA ke M ERS a
à Rare ARS
EN a a |
27. The term symbol forthe ground state ofehodium (Rh, atomic number 45) is ŸF. The electronic
configuration for this term symbol is
4) (Kel 4475 Es?
OR Mr ssp!
28. The red colour of oxyhemoglobín is manly dueto e
GG 4d tansition
(b) metal to ligand charge transfer transition
(© ligand to metal charge taser nica
(4) intra ligand x- x" transition
@ ye crystal field stabilization energy (CESE) value für FIi(H¿0)6]?* that has an absorption
rm at 492 nm is +
N (0) 20325 om! (9 1219500!
(©) 10,162 cm“! @8,1300m =
@ Inthe io-learonie series VO} CAO" and MO, a member ta nese charge ns
(N transitions. The incorrect statement is:
As @)CT transition ar attribute o excitations of electrons fom igand (9) o metal ()
(0) MO; exhibit charge transfer at shore wavelength among the three
(6) The waveengis of transions nema in ie rer VO} < CO < MO
(& The charge on metal mues increase in he oder VO} =O? < Maz
31. The increasing order of wavelength of absorption forthe complex ions
DICH" (i) (OC GÜDLCHOR)]* GWICHENIT” is
(@ivciiciciit @ivcireici
(icicióci > (Oi<i<icin
32. The comect order OFLMCT ee is:
(a) Mn; <a} < vor €) M10% > GO} > vor
onset >} <VOr (4) Ma0z < GO} > vor
(62 ie grand ste of igh pin otal ada Ot complexe ae respective
io! Tag and * Ay © Ty and Ay
Tig andy CRT
34. The complex that absorbs light of shortest wavelength is
de) {Core™
VO
OR
OK PX = OF)
electronic spectrum of (CrFs]” shows three bands at 14,900 cra”, 22,400 cm * and 34,800
em. The value of Ag inthis case it
(05500 cmt 6) 149000! 7
Q2400en* (Aa
(Tie number o spin allowed and el anton fo octahedral GU) complex wth oy
rod siti:
I om Wine
> Cone iur
31. Te number of miete for decom configuration is
axe wie
One 00
Te is excited state configunsin fr low pinocaheda system is:
pe on - -
7 OES OR Lei os a2
MoO} jon hors at 22000 er and 35000 em in, UV-visible Absorption spectrum. The
vale of y is
A ac ON
OEM (@6500en"*
£48) Addition of an aqueous solution of Fell) t potassium hexacyanochromate(I) pioduces a
‘rik-red colored comple, wich tums dark gen at [00"C, The dark green complex is:
@)FealCAN)s]s OOO
OKCHEECNE] FLAC)
41. The ground state term (NO) D is
(0) Te CE
Or CEA ce
42) An ion M?* forms the complexes [M(HL0)6 7", (M(ea)3}* and [.MBrs]?", match the
complex with appropriate colour: ,
@ gen blue and ed (0) bu, red and green
un red and blog (@red, blue and green
blue colour of Prussian ble isa esl of
(a) electron transfer between Fe(it) and Fe()
(9) electron transfer between Fe) and Fe(II}
(@ddtaansition £
(8) paramagnetic nature of Fe) end a.
MS y
an
vf gan?
00%
0: NA ke M ERS a
à Rare ARS
EN a a |
‘Gala Elin Socks RESET
44. Tce bands in th econ spectrum af [CNI )6]”" are due to he following asis:
A Tig © “dag (B) “Tag © Mag (C)7By © “Hag E
enti the corect statement about theo. /
ee
nen eines [Ae
À af) ui Quede
(tna od (Oo nt
[aes tet ern] ed
rota vi oc ya) ene
@9 crea 3
on (04 Li os
. The clectonic transition responsible forthe colour ofthe tansion meal oasis: 4)
) (a) dn de de do * >" we
ALES (Ode do?
47. Intense band st 15000 om in the UV-visible spectrum of [Bu MJa[Rez0ls]i due 0 de
asien
or 6-8 7
3-2 @x-8*
48, Silica gel contains (CoCl4]* as an indicator when acivat, silica gel becomes dark be while
upon absorption of moisture its colour changes to pale pink. This is because:
£a) Co) changes its coordination number from tetrahedral to octahedral +2
(0) Coll) changes its oxidation state to Cot)
(6) Tetrahedra eyital field spring is ot equal 0 octahedral erysa fed pling
(@,Co€t) forms kinetically able white Co( forms kinetically inert complexes
49. The light pink colour of [Co(H20)6]°* and the deep blue colour of (CoC, JF are due to
(0) MLCT transition in the first and transitions inthe second
(0) LMCT transition in bot
€) dd wansiions in both
(8) dd transition in frst and MLCT in the second
L@ 129 20 «a 50 ca 10
£0 20 © HH RO BH KO
5d 160 MO KO BO Me 10
2H BOTA BH MH MO BRO
B® 20 RO BH RH KE BO
LO MA FO »0 HH HO ea
em 40 68 40 10 40 0.0
1. The colour of trans (Coten)zF]* is less intense than that of cis (Coen) a}
2. Colour of tans Cole} Fo)" stes intense Uan hal o trans [Co(en)¿C1a
3. The three absorption bands for [CHFg]°" are observed in an electronic spectrum at 14900 cm,
22700 cm”! and 34400 cm”!. Determine the values of 8” and A,
4. The complex (Co(NHs)4]°* isyellow-orange whereas (Co(H20)) Fa is blue. Explain.
5. A aqueous solution of N(NOs)) is green. Addition of aqueous NH) causes the colour change to
ue. I etylenedianin is added oie green solution he colour changes o volt. Explain,
6. What are forbidden and alowed tanstions? Explain giving examples.
7. In general, UV-visible sbsertion bands of uasiion mal complexes are unsynmetic an broad
‘whereas those of tanthanoid ions (La™ )coruplexes are sharp.
8. CN” is ast gen. Do you exper Ka(Fe(CN)«]tbe intensely coloumé? À
9. CACO} is colourless whereas CAS is elo.
10. Cu? ions are colored and paramagnetic while Zn 2 ion are colouriess and diamagnetic.
AL. Characterize the origi of lern rasos in te following and indicate the inst of the
complexes : [CoCl4]””, (MB, [Fe(bipy)s ]°*, MnOz, [MA(2120)6]?", KFelFe(CN)g}
Fe4(Fe(CN)]s,Cr2037, CAS, Ni(CO)4
12. Dimelhyl sulphoxide (DMSO) reacts wit Co(C10, )a in ethanol to form pnkeolored compound
(4) hich has a magetc manent of 49 B.M, However when DMSO rect with CoCI a dk bla
coloured compound (8) is formed which has a magnetic moment of 4.6 B.M.
(D Suggest formula nd sucre of compound (4) and (8).
) Rationaize the color of hse comples.
13, Iron forms K(Fe(CN)g} KaQFACNg} Fe[Fe(CN)g} Fea(Fe(CN)g) and KFe(F(CNg}
‘complexes. KFe[Fe(CN};) is more intensely coloured than the other complexes. Explain
14. The absorption spectrum of (TKH,0)]”* shows one band as broad and unsymmetrical, Explain.
15. Solutions of the complexes Calg} and {COL °° where Land L’ are two dient neural
monodentate ligands, ac pink and yellow respectively. Which would be expected t have the
higher value of 4, ?
16. Aqueous solution of Cis violet in colour whereas aqueous solution of tI) and La(1I)
‘which belong 10 same group ae colourless. Explain
17. Oxyhemoglobin is bright ed whereas deoxyhemoglobin is purple. Explsi,
18. À concentrated aqueous solution of CaCl is bright green whereas, hen this solution i died,
te solution becomes light blu. Explain,
19. High spin octahedral complexes of Ma?* ion re colourless. Explain,
20. Aqueous solution of Nit) is green coloured whereas that of Zn(1) is coloures. Explain
44. Tce bands in th econ spectrum af [CNI )6]”" are due to he following asis:
A Tig © “dag (B) “Tag © Mag (C)7By © “Hag E
enti the corect statement about theo. /
ee
nen eines [Ae
À af) ui Quede
(tna od (Oo nt
[aes tet ern] ed
rota vi oc ya) ene
@9 crea 3
on (04 Li os
. The clectonic transition responsible forthe colour ofthe tansion meal oasis: 4)
) (a) dn de de do * >" we
ALES (Ode do?
47. Intense band st 15000 om in the UV-visible spectrum of [Bu MJa[Rez0ls]i due 0 de
asien
or 6-8 7
3-2 @x-8*
48, Silica gel contains (CoCl4]* as an indicator when acivat, silica gel becomes dark be while
upon absorption of moisture its colour changes to pale pink. This is because:
£a) Co) changes its coordination number from tetrahedral to octahedral +2
(0) Coll) changes its oxidation state to Cot)
(6) Tetrahedra eyital field spring is ot equal 0 octahedral erysa fed pling
(@,Co€t) forms kinetically able white Co( forms kinetically inert complexes
49. The light pink colour of [Co(H20)6]°* and the deep blue colour of (CoC, JF are due to
(0) MLCT transition in the first and transitions inthe second
(0) LMCT transition in bot
€) dd wansiions in both
(8) dd transition in frst and MLCT in the second
L@ 129 20 «a 50 ca 10
£0 20 © HH RO BH KO
5d 160 MO KO BO Me 10
2H BOTA BH MH MO BRO
B® 20 RO BH RH KE BO
LO MA FO »0 HH HO ea
em 40 68 40 10 40 0.0
1. The colour of trans (Coten)zF]* is less intense than that of cis (Coen) a}
2. Colour of tans Cole} Fo)" stes intense Uan hal o trans [Co(en)¿C1a
3. The three absorption bands for [CHFg]°" are observed in an electronic spectrum at 14900 cm,
22700 cm”! and 34400 cm”!. Determine the values of 8” and A,
4. The complex (Co(NHs)4]°* isyellow-orange whereas (Co(H20)) Fa is blue. Explain.
5. A aqueous solution of N(NOs)) is green. Addition of aqueous NH) causes the colour change to
ue. I etylenedianin is added oie green solution he colour changes o volt. Explain,
6. What are forbidden and alowed tanstions? Explain giving examples.
7. In general, UV-visible sbsertion bands of uasiion mal complexes are unsynmetic an broad
‘whereas those of tanthanoid ions (La™ )coruplexes are sharp.
8. CN” is ast gen. Do you exper Ka(Fe(CN)«]tbe intensely coloumé? À
9. CACO} is colourless whereas CAS is elo.
10. Cu? ions are colored and paramagnetic while Zn 2 ion are colouriess and diamagnetic.
AL. Characterize the origi of lern rasos in te following and indicate the inst of the
complexes : [CoCl4]””, (MB, [Fe(bipy)s ]°*, MnOz, [MA(2120)6]?", KFelFe(CN)g}
Fe4(Fe(CN)]s,Cr2037, CAS, Ni(CO)4
12. Dimelhyl sulphoxide (DMSO) reacts wit Co(C10, )a in ethanol to form pnkeolored compound
(4) hich has a magetc manent of 49 B.M, However when DMSO rect with CoCI a dk bla
coloured compound (8) is formed which has a magnetic moment of 4.6 B.M.
(D Suggest formula nd sucre of compound (4) and (8).
) Rationaize the color of hse comples.
13, Iron forms K(Fe(CN)g} KaQFACNg} Fe[Fe(CN)g} Fea(Fe(CN)g) and KFe(F(CNg}
‘complexes. KFe[Fe(CN};) is more intensely coloured than the other complexes. Explain
14. The absorption spectrum of (TKH,0)]”* shows one band as broad and unsymmetrical, Explain.
15. Solutions of the complexes Calg} and {COL °° where Land L’ are two dient neural
monodentate ligands, ac pink and yellow respectively. Which would be expected t have the
higher value of 4, ?
16. Aqueous solution of Cis violet in colour whereas aqueous solution of tI) and La(1I)
‘which belong 10 same group ae colourless. Explain
17. Oxyhemoglobin is bright ed whereas deoxyhemoglobin is purple. Explsi,
18. À concentrated aqueous solution of CaCl is bright green whereas, hen this solution i died,
te solution becomes light blu. Explain,
19. High spin octahedral complexes of Ma?* ion re colourless. Explain,
20. Aqueous solution of Nit) is green coloured whereas that of Zn(1) is coloures. Explain
21. The{Cx(H,0)6)°* ions violet in colour whereas [Ce{CN)¢]? is yellow. Explain,
22. The single absorption bands for(Ti{H,0)6]°* and[TWQNCS) Joecur in their absorption spectra at
A7O nena 54 nmrespetvly.() Clclate he crystal Fel split encres or se complex
ions in mal”. (i) Pret the colors ofthese complex ions.
28. The complex (COMO) eh pak whereas[CoCl, is lie, Explat.
24. Colour oF CuSO, SHO ble. Exp.
kr} todita ooo
tal may [2
Onde prone élit
D
pros
iamaar cue pel >. ln
TIMES
Wena sac pen arenal or apie ga fl ri induced circulation
fie cles int substance. This induced iculationafelecrons ist a mate omentor|
‘magnetic el hit usually oppass te applied magnetic fil. Asaresltheauhstacei reeled by the
‘magnetic field and this eft aid wo be: ic effect. This effec is caused bythe presence of
paired electrons: The damgnetc effect exists only when a substances is placed ina mago field. This
alado ny mp ¿paren 2
effect arises in substances ia which there are only paired electro or priced electons along with
unpaired electrons fa substances has only paired electrons, the diamagnetic effects dominated. On the
‘other han, fa substance has paired as well as unpaired electron, the paramagnetic effects dominated
‘The substances having only paired electrons exhibit a weak magnetic moment known as
iamagnetism and such substances ae called diamagnetic substances. In these substances, the induced
circulation of electrons occurs with inthe orbitals ofthe substances that ace occupied athe ground state.
La some cases the molecules are paramagnetic despite having only pared cectrons, the induced
‘magnetic moments aligned inthe direction of applied magnetic field because they use LUMO that i
lase to HOMO in energy. This obit paramagaciism can be distinguished oro pin paramagnetism by
‘the fact that i is temperate independent and ı is called temperature independent paramagnetisn
because the elections preset in HOMO can be excited to LUMO by thermal tion,
‘Any substance that fas one or more unpaired efectrons exhibits stronger and permanent magneti |
property is known as paramagnetism. Paramagnetism aries fom the spin and cbital motion of the
unpeired electrons in the absence of an external magnetic field. Such substaces ae sid to be para-
magnetic. When a paramagnetic substance is placed in an external magnetic Sel, the permanent
magnetic moments tend to align themselves isthe direction ofthe extemal magnetic ie and a result
are attracted into the extemal magnetic field, Since the paramagnetic effect is much larger than the
‘damage effect nd opposite to the diamagnetic effect, the paramagnetic eft, therefore cancels the
lamagnetic effet, Hence paramagnetic effect is dominant in all substances containing ether one or
‘more uspaired electrons. Thus, due to net paramagnetic effect the substances is atracted into he
‘extemal magnetic eld. un
in e absence of external magnetic field, the magnetic moments of individual molecules are
radamized by thermal motion andthe substances, as a resul, hag no magnetic moment because the
‘andamizaton of individual magnetic moments causes cancellation of one ane as shown in Figure
64
22. The single absorption bands for(Ti{H,0)6]°* and[TWQNCS) Joecur in their absorption spectra at
A7O nena 54 nmrespetvly.() Clclate he crystal Fel split encres or se complex
ions in mal”. (i) Pret the colors ofthese complex ions.
28. The complex (COMO) eh pak whereas[CoCl, is lie, Explat.
24. Colour oF CuSO, SHO ble. Exp.
kr} todita ooo
tal may [2
Onde prone élit
D
pros
iamaar cue pel >. ln
TIMES
Wena sac pen arenal or apie ga fl ri induced circulation
fie cles int substance. This induced iculationafelecrons ist a mate omentor|
‘magnetic el hit usually oppass te applied magnetic fil. Asaresltheauhstacei reeled by the
‘magnetic field and this eft aid wo be: ic effect. This effec is caused bythe presence of
paired electrons: The damgnetc effect exists only when a substances is placed ina mago field. This
alado ny mp ¿paren 2
effect arises in substances ia which there are only paired electro or priced electons along with
unpaired electrons fa substances has only paired electrons, the diamagnetic effects dominated. On the
‘other han, fa substance has paired as well as unpaired electron, the paramagnetic effects dominated
‘The substances having only paired electrons exhibit a weak magnetic moment known as
iamagnetism and such substances ae called diamagnetic substances. In these substances, the induced
circulation of electrons occurs with inthe orbitals ofthe substances that ace occupied athe ground state.
La some cases the molecules are paramagnetic despite having only pared cectrons, the induced
‘magnetic moments aligned inthe direction of applied magnetic field because they use LUMO that i
lase to HOMO in energy. This obit paramagaciism can be distinguished oro pin paramagnetism by
‘the fact that i is temperate independent and ı is called temperature independent paramagnetisn
because the elections preset in HOMO can be excited to LUMO by thermal tion,
‘Any substance that fas one or more unpaired efectrons exhibits stronger and permanent magneti |
property is known as paramagnetism. Paramagnetism aries fom the spin and cbital motion of the
unpeired electrons in the absence of an external magnetic field. Such substaces ae sid to be para-
magnetic. When a paramagnetic substance is placed in an external magnetic Sel, the permanent
magnetic moments tend to align themselves isthe direction ofthe extemal magnetic ie and a result
are attracted into the extemal magnetic field, Since the paramagnetic effect is much larger than the
‘damage effect nd opposite to the diamagnetic effect, the paramagnetic eft, therefore cancels the
lamagnetic effet, Hence paramagnetic effect is dominant in all substances containing ether one or
‘more uspaired electrons. Thus, due to net paramagnetic effect the substances is atracted into he
‘extemal magnetic eld. un
in e absence of external magnetic field, the magnetic moments of individual molecules are
radamized by thermal motion andthe substances, as a resul, hag no magnetic moment because the
‘andamizaton of individual magnetic moments causes cancellation of one ane as shown in Figure
64
Inthe presence ofextemal magnetic field, there is competition between andaization of individual
enti omens die o thermal motion and fiel stengh fr alignmet. Consequently, paramagnetic
4 desees in magnitude asthe temipereture increases. I is due o theft tata increases in
estar increase randamization and decreases the paranagnet fet. The aramgnetic character
vi nesses in the number of unpare elesrons.
‘The measurement of magnetic properties experimentally doesnot involve the measurement of
moment but instead magnetic moment is cakulted om the measurement of magnetic
iby, When a substance i placed in an extema fied of strength (2), be induced magnetic field
produced inthe substance wileither be greater an restan he appli ik depending whether
substances paramagnetic o damagaetc. The difference between induced magnetic field (8) inthe
and applied magnetic field (A is given by, >
AH=B-H 0
“The diffrence between the applied magnetic field nd ho inde magnetic feld in substance is.
essed in terms of intensity of magnetization (/) as shown below
A = BH (o
"e intensity of magnetization is the magnetic moment per unit volume,
ri induced magnetic els (B) and intensity of magnetization bah are proportion to the applied
ic eld ($) Now divide the equation (i) by H, we ga,
iu By (iy
ct ce te net presi ad e to a as gn
in the sample tothe density of in
he em Js the magnetic susceptibility per
of magnetic force in vacuum.
volume ofthe substance and sealed volume
ic susceptibility (x). The quantity « is measure of the extent 9 which a substance tends to be
ried
2 iv)
amd (0)
[The quantity xis positive for paramagnetic substances and negativo fordiamagnetié substances, tis
osioles quantity, The volume susceptibility is concentration dependent Ofte, the magnetic
ibility obtained experimentally i he specific (or mass) susceptibility (Gi) and itis obtained
viding bythe density of the sample,
1. 0
Finally a mola suscep
sample
Molermagnatc susceptibility i measure of the degre to whichone mole ofa substance interacts
‘ihe applied maget ld
The magneti susepibility measured fra substance consi of conibutions from paramagnetic
and damogneic msceptilies. The paramapneic suscpübliy ts much greater than that of
dismi substance, Por a diamagnetic substance, he dias ne suscepbity willbe the sum of
contains fom its consent atoms. For subsancss ring very sol diamagneim 35
compared to pasanapuetism, then it can be neglecta. I a sance contas Large number of
diamagoeiatoms pec paramagnetic atom (a in melon comple), the damapneie eontribuion wil
te sinifcant ad an not be neglected Its observed that magna is an adie quant and the
diansenctie asbl of e substance can be obtained asasamofomtibuions from each consent
sions. Ifa mbstasce contains paied a5 well as unaiced less, e applied field induces a
mani in opposition to the paramagncism ofthe unid electron. Thus, it reduces the
suscepti o te sample below that which i du to puranagpetu alone. The measured magnetic
sxsepibty smu be comeced by subtracting diamagnetic suey Boni.
Conecte or paramagnetic suscepsvilty
= measured susceptibility ~ diamagnetic susspibiliy
thy tha he ‘iy
Since the diamagnetic susceptibility isa negative quantity, the ahove relationship canbe written as:
rem
AA) io
From casa tbc), ie corrected molar suscepibily Cel to the effective magnetio
a de rai ola lts im
RE (x)
Where Mis Avogadro number (= 6.023 *1075), Tis the absolute temperature, R isthe ideal gas
‘constant, gg is expressed in Bohr magnetons (B.M.).
SRT 14 E
:
pa MG RM EBM À) a)
ie Cai as shown that paramagnetic susceptiiliy isovenslypropnional tothe absolute
temperate, à
2 =2
tue o
4,
0
‘Where Cis Cure constant and is equal to
enti omens die o thermal motion and fiel stengh fr alignmet. Consequently, paramagnetic
4 desees in magnitude asthe temipereture increases. I is due o theft tata increases in
estar increase randamization and decreases the paranagnet fet. The aramgnetic character
vi nesses in the number of unpare elesrons.
‘The measurement of magnetic properties experimentally doesnot involve the measurement of
moment but instead magnetic moment is cakulted om the measurement of magnetic
iby, When a substance i placed in an extema fied of strength (2), be induced magnetic field
produced inthe substance wileither be greater an restan he appli ik depending whether
substances paramagnetic o damagaetc. The difference between induced magnetic field (8) inthe
and applied magnetic field (A is given by, >
AH=B-H 0
“The diffrence between the applied magnetic field nd ho inde magnetic feld in substance is.
essed in terms of intensity of magnetization (/) as shown below
A = BH (o
"e intensity of magnetization is the magnetic moment per unit volume,
ri induced magnetic els (B) and intensity of magnetization bah are proportion to the applied
ic eld ($) Now divide the equation (i) by H, we ga,
iu By (iy
ct ce te net presi ad e to a as gn
in the sample tothe density of in
he em Js the magnetic susceptibility per
of magnetic force in vacuum.
volume ofthe substance and sealed volume
ic susceptibility (x). The quantity « is measure of the extent 9 which a substance tends to be
ried
2 iv)
amd (0)
[The quantity xis positive for paramagnetic substances and negativo fordiamagnetié substances, tis
osioles quantity, The volume susceptibility is concentration dependent Ofte, the magnetic
ibility obtained experimentally i he specific (or mass) susceptibility (Gi) and itis obtained
viding bythe density of the sample,
1. 0
Finally a mola suscep
sample
Molermagnatc susceptibility i measure of the degre to whichone mole ofa substance interacts
‘ihe applied maget ld
The magneti susepibility measured fra substance consi of conibutions from paramagnetic
and damogneic msceptilies. The paramapneic suscpübliy ts much greater than that of
dismi substance, Por a diamagnetic substance, he dias ne suscepbity willbe the sum of
contains fom its consent atoms. For subsancss ring very sol diamagneim 35
compared to pasanapuetism, then it can be neglecta. I a sance contas Large number of
diamagoeiatoms pec paramagnetic atom (a in melon comple), the damapneie eontribuion wil
te sinifcant ad an not be neglected Its observed that magna is an adie quant and the
diansenctie asbl of e substance can be obtained asasamofomtibuions from each consent
sions. Ifa mbstasce contains paied a5 well as unaiced less, e applied field induces a
mani in opposition to the paramagncism ofthe unid electron. Thus, it reduces the
suscepti o te sample below that which i du to puranagpetu alone. The measured magnetic
sxsepibty smu be comeced by subtracting diamagnetic suey Boni.
Conecte or paramagnetic suscepsvilty
= measured susceptibility ~ diamagnetic susspibiliy
thy tha he ‘iy
Since the diamagnetic susceptibility isa negative quantity, the ahove relationship canbe written as:
rem
AA) io
From casa tbc), ie corrected molar suscepibily Cel to the effective magnetio
a de rai ola lts im
RE (x)
Where Mis Avogadro number (= 6.023 *1075), Tis the absolute temperature, R isthe ideal gas
‘constant, gg is expressed in Bohr magnetons (B.M.).
SRT 14 E
:
pa MG RM EBM À) a)
ie Cai as shown that paramagnetic susceptiiliy isovenslypropnional tothe absolute
temperate, à
2 =2
tue o
4,
0
‘Where Cis Cure constant and is equal to
EE
BER:
‘This expresion is known as Cure Law, This law is restatemeat of equation (xi.
“The Curie’s law is valid only for peramognetc substances that are magneticaly dilute. The para
magnetic susceptibility (corrected for diamagnaion) ploued versus the reciprocal of the absolute
temperature (or reciprocal of paramagnetic susceptibility versus absolute temperature) produces a
straight ine with ero intercept (Figure 6.2) and slope C. In some substances that are not magnetically
dilute, the magnetic moments of unpaired elecrons on neighbouring atoms may couple with each other.
‘These substances may behave as ciber ferromagnetic or Rerimagneti or at-fercomagnetc. These
compounds obey te Curie-Weiss law.
pa
€
si)
]
here D, an empirical constan isthe temperature at which the tne intercepts the Taxis in a pot of
1x2, versus 7. In this plot the inercept fr thse substances is wot zero (Figure 62). For these
compounds, the magnetic moment ta given temperature can be alle from the equation,
pa 284 ra iv)
Ifthe value of is posiive, te suban sad tbe eromagnci ad ifthe value FO repaire
the substance i said ob ant fromage
if there i interecton between the magnetic moment on neiibouing atoms ofa paramagnetic
substane, spontaneous ordering Figure 63) ofthe magnetic momeat occur below a pair
tempera called as etal empece, 1 agama ofl he magic moment of neighbouring
tom in he same direction end produce a permanent magnetic moment, the substance ssi o be
feromagnetic andthe erical temperature i alte he Cure temperature, fc. Abow his temperature
the subie haves 25 a nomal parmognee aban. Below Carte temperature 7, fr 3
fromage substances mui he a 4, fora roma prmpeio substance. Below Te te
EA
"Esomgneio substance obey Cuie-Weis lw. Fe, Co NiandCrO; exhibit feromagnetic below Cure
temperatures 1043 K, 1404 K, 631 K and 386 K respectively
some ofthe magnetic moments re system aligned opposite tothe others to give rest
magnetic moment, the substance i sad to be femtagnetic and the cria temperature once aa is
called the Curie temperature, Tc. An important erample of ferimagnetic substance is magnet,
e304 In this substance, the magnetic moments of Fe) and FI ar aligned in opposite ietions
nd de resultat magnetic moments only rom Fe) moments
NO Se) je2 2]. ie
NA SS} [ess ==>
Rett =| [222] ESS
Nsw Sc] 2] 3
ta CES a @
Hfhaifof the magnetic moments are aligned in opposite rection tothe other hal resulting ina net
2210 magnetic momen, the substance is sid be antiferomagaeti and the critical temperature is called
the Neel temperature. MnO is an anti-eromagnetic substance with Neel temperature of 116 K.
In Mn, there is 20 interaction between the halfflo , oritals of Min ions and the filled pe
cit of oxide ion a shown below
The spns ofall the five d-leczonsin one Ma? ar opposite a of other Ma?* ion. The oxide
lectron which interacts with Mn st aves pn opposite to that of May electron Leaving anclesron
of oposite spin to interact with Mn. hero the manganese leon ae ant-feromagetily
couple An ar example of n-Rrromagnetic stance NO.
Variation of magnetic susceptibility with temperature fr damagntc, paramagnetic, eromagotie
(oc erimagnetic) and at-Feremagnetic substances is shown is Figure 64.
BER:
‘This expresion is known as Cure Law, This law is restatemeat of equation (xi.
“The Curie’s law is valid only for peramognetc substances that are magneticaly dilute. The para
magnetic susceptibility (corrected for diamagnaion) ploued versus the reciprocal of the absolute
temperature (or reciprocal of paramagnetic susceptibility versus absolute temperature) produces a
straight ine with ero intercept (Figure 6.2) and slope C. In some substances that are not magnetically
dilute, the magnetic moments of unpaired elecrons on neighbouring atoms may couple with each other.
‘These substances may behave as ciber ferromagnetic or Rerimagneti or at-fercomagnetc. These
compounds obey te Curie-Weiss law.
pa
€
si)
]
here D, an empirical constan isthe temperature at which the tne intercepts the Taxis in a pot of
1x2, versus 7. In this plot the inercept fr thse substances is wot zero (Figure 62). For these
compounds, the magnetic moment ta given temperature can be alle from the equation,
pa 284 ra iv)
Ifthe value of is posiive, te suban sad tbe eromagnci ad ifthe value FO repaire
the substance i said ob ant fromage
if there i interecton between the magnetic moment on neiibouing atoms ofa paramagnetic
substane, spontaneous ordering Figure 63) ofthe magnetic momeat occur below a pair
tempera called as etal empece, 1 agama ofl he magic moment of neighbouring
tom in he same direction end produce a permanent magnetic moment, the substance ssi o be
feromagnetic andthe erical temperature i alte he Cure temperature, fc. Abow his temperature
the subie haves 25 a nomal parmognee aban. Below Carte temperature 7, fr 3
fromage substances mui he a 4, fora roma prmpeio substance. Below Te te
EA
"Esomgneio substance obey Cuie-Weis lw. Fe, Co NiandCrO; exhibit feromagnetic below Cure
temperatures 1043 K, 1404 K, 631 K and 386 K respectively
some ofthe magnetic moments re system aligned opposite tothe others to give rest
magnetic moment, the substance i sad to be femtagnetic and the cria temperature once aa is
called the Curie temperature, Tc. An important erample of ferimagnetic substance is magnet,
e304 In this substance, the magnetic moments of Fe) and FI ar aligned in opposite ietions
nd de resultat magnetic moments only rom Fe) moments
NO Se) je2 2]. ie
NA SS} [ess ==>
Rett =| [222] ESS
Nsw Sc] 2] 3
ta CES a @
Hfhaifof the magnetic moments are aligned in opposite rection tothe other hal resulting ina net
2210 magnetic momen, the substance is sid be antiferomagaeti and the critical temperature is called
the Neel temperature. MnO is an anti-eromagnetic substance with Neel temperature of 116 K.
In Mn, there is 20 interaction between the halfflo , oritals of Min ions and the filled pe
cit of oxide ion a shown below
The spns ofall the five d-leczonsin one Ma? ar opposite a of other Ma?* ion. The oxide
lectron which interacts with Mn st aves pn opposite to that of May electron Leaving anclesron
of oposite spin to interact with Mn. hero the manganese leon ae ant-feromagetily
couple An ar example of n-Rrromagnetic stance NO.
Variation of magnetic susceptibility with temperature fr damagntc, paramagnetic, eromagotie
(oc erimagnetic) and at-Feremagnetic substances is shown is Figure 64.
Mises
Magnetic susoaptb x —+
Magnate suscopt x —-
Tongo) — Tonperia 0 —
ta Cc)
Magnete suseoptby, x —e
Magnete sueoopi
Torero (9 —
Magnetic Moment
‘When charged pane subjected tobe in motion, a magnetic moments produced. There ae two
‘types of electron motion (eecron treating the charged particle) tha give rise to magnetic moments The
fist sth electron spin which isthe rotation of electron about ts axis. The magnetic moment cesling
from this electron spin is called the spin magnetic moment (u) which is characterised by the spin
angular momentum quactum number, $. The second is dhe electron orbiting about the nucleus. The
magnetic moment resul fom his electron orbiting is called the orbital magnetic moment which
is characterised by total orbital angular momeatum L. Thus the magnetic moment of parmaguetio
substance is due othe contribution fom spins and orbital motions of unpaired electrons.
‘The magnetic moment of «paramagnetic substance depends upon the energy diffrence between *
cent tates of values and(J +1) lager, and (7 states ae e ground ad fst exci
states respectively, The energy dice between two adjacent states is given by the expresion
(I O1) where called the piace coupling constant. Let us conside, or example, F sof?
configuration fc which2S +1 =30c8 = land L= 3forFtermand J=4,3,2. Thus, *F site plis into
3, Fs and Ÿ Fa sates Each fe states have thc definite amount of eerie.
‘According to Hund’srlethe 3 Fp states ground state and energies ofthese stats increase inthe
‘order Ÿ Fy < 35 < ŸFa. The enemy difference between successive pairs ofthese sates is 3h and 4,
respectively. In mage ied hse states ae further pit ino QJ +1) dirt at ah wich is
‘separated from adjacent state by an energy gpg H, where g is a constant called as Lande splitting factor
forthe substance, iste mag eld andy ithe Bohr magneton. The split pate fo te
is shown in Figure
‘The value of is very sual fright atoms and arger forthe heavier atoms. The extent which the
states corresponding tn diffrent J values are populated at ordinary temperature depends upon how large
the energy difference between ground and excited states as compare with the thermal energy available,
MT.
AL300K,
= 200m!
Ifthe separation between ground state and first excited state is sufficiently lege de, > K then spin
‘orbit coupling (LS coupling) will be appreciable. Such a situation arises in heavier elements, particular
for inthanoids, For such substances the magnetic moment is given bj,
weg) 0)
where Ji the total segular momentum quantum number and g isthe Lande sling factor for the
electron.
JU +5540 LLE
Lo ET]
3,58+D-4L+0
il ET
3 = L+S fo moce than hal filled sobsbell
and J = L$ fo less than bal ile subshell.
Magnetic susoaptb x —+
Magnate suscopt x —-
Tongo) — Tonperia 0 —
ta Cc)
Magnete suseoptby, x —e
Magnete sueoopi
Torero (9 —
Magnetic Moment
‘When charged pane subjected tobe in motion, a magnetic moments produced. There ae two
‘types of electron motion (eecron treating the charged particle) tha give rise to magnetic moments The
fist sth electron spin which isthe rotation of electron about ts axis. The magnetic moment cesling
from this electron spin is called the spin magnetic moment (u) which is characterised by the spin
angular momentum quactum number, $. The second is dhe electron orbiting about the nucleus. The
magnetic moment resul fom his electron orbiting is called the orbital magnetic moment which
is characterised by total orbital angular momeatum L. Thus the magnetic moment of parmaguetio
substance is due othe contribution fom spins and orbital motions of unpaired electrons.
‘The magnetic moment of «paramagnetic substance depends upon the energy diffrence between *
cent tates of values and(J +1) lager, and (7 states ae e ground ad fst exci
states respectively, The energy dice between two adjacent states is given by the expresion
(I O1) where called the piace coupling constant. Let us conside, or example, F sof?
configuration fc which2S +1 =30c8 = land L= 3forFtermand J=4,3,2. Thus, *F site plis into
3, Fs and Ÿ Fa sates Each fe states have thc definite amount of eerie.
‘According to Hund’srlethe 3 Fp states ground state and energies ofthese stats increase inthe
‘order Ÿ Fy < 35 < ŸFa. The enemy difference between successive pairs ofthese sates is 3h and 4,
respectively. In mage ied hse states ae further pit ino QJ +1) dirt at ah wich is
‘separated from adjacent state by an energy gpg H, where g is a constant called as Lande splitting factor
forthe substance, iste mag eld andy ithe Bohr magneton. The split pate fo te
is shown in Figure
‘The value of is very sual fright atoms and arger forthe heavier atoms. The extent which the
states corresponding tn diffrent J values are populated at ordinary temperature depends upon how large
the energy difference between ground and excited states as compare with the thermal energy available,
MT.
AL300K,
= 200m!
Ifthe separation between ground state and first excited state is sufficiently lege de, > K then spin
‘orbit coupling (LS coupling) will be appreciable. Such a situation arises in heavier elements, particular
for inthanoids, For such substances the magnetic moment is given bj,
weg) 0)
where Ji the total segular momentum quantum number and g isthe Lande sling factor for the
electron.
JU +5540 LLE
Lo ET]
3,58+D-4L+0
il ET
3 = L+S fo moce than hal filled sobsbell
and J = L$ fo less than bal ile subshell.
‘Since f suche is less than half
S=l=S =5-164
3,565 +0 +)
ij 2107)
Er]
2
3
Be
2
4
=08
u-08/Id+D BM.
=03/2) BM.
35FBM a
‘This calculated value is very close to the experimental value 347 BM,
"Te calculated magnetic moments by the above formula for anthanoides have good agreement with
‘observed values. For most lanthanoides the value of. is about 1000cm”*, However) value for Eu *
and Sm? is about 300em™ which isa small value, Therefore, the agreement for Eu * and Sm?" is
not very good.
For complexes in which? value is small and separation between ground sae and he fit excited is
smal (CAT), spin-obit couplings negligible but spin and octal contributions bth ae significant, In
‘these complexes spin and orbital magnetic moments of electrons function independently For electron
spin only, L=Q JS
and
5S +0
For till motion aly,
Ths, can be alt by the expres
n= 45 +) EM. «iy
7
EEE
In case of complexs fanion metas of seis, eigens ih ect maton of
teen od ult snd ence the magneti moment due tal ton of cco edt
‘lente and bil contain canbe glei Le, 0, LL Dsl quo.
There, be moguetc moment may be considered to be are oly du o sis of unpaired
tects The tn rete
: JSST OM.
"This equation is known as spin only formula for magnetic moment.
Hee SE D BM
Loue of pied leone, then
oy
and us = RD) BM. ot up
vest 2027310 jones IT!)
where eis een charge, is Planks constant and mise us flan, The callate
values of pineal maga moment fo 1,2, 3, 4 and $ unpied clous ar 73,243, 387,490
and 592 recia, 2
‘The calculated and experimental magnetic moments for complexes of transition elements of
seri are given in table 6.
The able, indicatesthat he experimental magnetic moments for complexe of frst ow transition
real is 0 no agree wi those calculated by equations (and (i. Though her is good agreement
between experimental magnetic moment and calculated by spin only formula (i, however, ia some
cases, the experimental magnetic moment is higher than that of calculated by spin only formula. This is
‘ue to some rita combat.
The orbital conidios posible only wher an orbital wll wansformintoan equivalent obit by
rotation. The ng obit (dy, dye and da) canbe tanned ito each er by rotting bout an axis
bby 90" The eg, abilals (72 and 2) can not be.ransformed suo one another because these have
«ir shapes eet, ese bias have no orbital contribution, al the 1 obi ar singly
‘occupied ent isnot possible to transform an orbital, say the dy orbital into d 0 d,, bia because
they already contain an electron with same spin as the incoming electron. Sim, iis impossible to
transforme a al tbe al te bill are doubly ocupe Ts, 3 cias wie),
snd, conga ae no aa conibuions. The confins oran), and make
ital conri 1 te magnetic moments of octahedral complexes, These, in act
‘completes te allowing anfing make otal contributions
IGA PLS, VD, ALS) ALE)
The long configuro a octahedral complees of Tit series rason metal eas bave no
oral eontibtns
PEO BH, BUSI). AED, PEA SL)
S=l=S =5-164
3,565 +0 +)
ij 2107)
Er]
2
3
Be
2
4
=08
u-08/Id+D BM.
=03/2) BM.
35FBM a
‘This calculated value is very close to the experimental value 347 BM,
"Te calculated magnetic moments by the above formula for anthanoides have good agreement with
‘observed values. For most lanthanoides the value of. is about 1000cm”*, However) value for Eu *
and Sm? is about 300em™ which isa small value, Therefore, the agreement for Eu * and Sm?" is
not very good.
For complexes in which? value is small and separation between ground sae and he fit excited is
smal (CAT), spin-obit couplings negligible but spin and octal contributions bth ae significant, In
‘these complexes spin and orbital magnetic moments of electrons function independently For electron
spin only, L=Q JS
and
5S +0
For till motion aly,
Ths, can be alt by the expres
n= 45 +) EM. «iy
7
EEE
In case of complexs fanion metas of seis, eigens ih ect maton of
teen od ult snd ence the magneti moment due tal ton of cco edt
‘lente and bil contain canbe glei Le, 0, LL Dsl quo.
There, be moguetc moment may be considered to be are oly du o sis of unpaired
tects The tn rete
: JSST OM.
"This equation is known as spin only formula for magnetic moment.
Hee SE D BM
Loue of pied leone, then
oy
and us = RD) BM. ot up
vest 2027310 jones IT!)
where eis een charge, is Planks constant and mise us flan, The callate
values of pineal maga moment fo 1,2, 3, 4 and $ unpied clous ar 73,243, 387,490
and 592 recia, 2
‘The calculated and experimental magnetic moments for complexes of transition elements of
seri are given in table 6.
The able, indicatesthat he experimental magnetic moments for complexe of frst ow transition
real is 0 no agree wi those calculated by equations (and (i. Though her is good agreement
between experimental magnetic moment and calculated by spin only formula (i, however, ia some
cases, the experimental magnetic moment is higher than that of calculated by spin only formula. This is
‘ue to some rita combat.
The orbital conidios posible only wher an orbital wll wansformintoan equivalent obit by
rotation. The ng obit (dy, dye and da) canbe tanned ito each er by rotting bout an axis
bby 90" The eg, abilals (72 and 2) can not be.ransformed suo one another because these have
«ir shapes eet, ese bias have no orbital contribution, al the 1 obi ar singly
‘occupied ent isnot possible to transform an orbital, say the dy orbital into d 0 d,, bia because
they already contain an electron with same spin as the incoming electron. Sim, iis impossible to
transforme a al tbe al te bill are doubly ocupe Ts, 3 cias wie),
snd, conga ae no aa conibuions. The confins oran), and make
ital conri 1 te magnetic moments of octahedral complexes, These, in act
‘completes te allowing anfing make otal contributions
IGA PLS, VD, ALS) ALE)
The long configuro a octahedral complees of Tit series rason metal eas bave no
oral eontibtns
PEO BH, BUSI). AED, PEA SL)
ge
In the similar way, the tetrahedral complexes with the following configurtions have orbital
coatibuions
PEMA), arf) and P(e)
‘Table 6.1 : Experimental and Calculated Values of Magnetic Moments for
‘Some High Spin and Low Spin Octahedral Complexes,
el
we 0 à hs in | = =
ve 2 2 jamsass|2e |- a 2
ar 3 3 130300 [38 . |- a i
ar 4 a |475-490|490 12 320-330 | 283
ma? s 5 jss-o|se | 180-210 | 1.73
Ret 5 s Iso |sn |i 2025 [1
Re 6 a [s10-s70 450. Jo = =
ct 7 1430-520 (388 + |1 18 13
wi 8 2 283528 | = =
art 9 1 Jura lim |- = es
In ger, ba contribution is posible incomplete in which the ground state of metal ion is
ecrnically triply degenerate (€, 234). On te other hand the orbital contribution is not posible in
‘complexes in which he ground tte of metal fn ¡electronica on degene ox doubly degenerate
(eg dag ory)
Alia sted complex of (5, mei onhave cst an experimen magna
moments of 3.87 and 52 BLM. respectively: The higher value of experimental magnetic moment is
expected becas ofthe rl contin, Friera enmle(CaCa]™ (13) the calculated
and experimental magnetic moments are 3.87 and 4. B M. respectively. In is case the higher value of
‘xperimentaf magnetic moment isnot due 0 orbital contiaton. Although in most of the complexes
with or E ground state the quenching ofthe orbital cotibuton is expected o be complete and the
experimental magnetic moment is very close o spin ocly magnetic moment and is temperature
independent However in some complexes there isthe deviation ofthe experimental magnetic moment
from the spin only magnetic omen. This due to the temperature independent paramagnetis,
TR inswcheasesthefistexcited stat, fof same spin mol asthe ground ste) mixes up with À
or E ground sate doe to spin omit coupling. For those complex in which spin-orbit coupling is
signifiant, the following equation is used to calcule
a
sus (1-2
‘Where isaconstant which depends upon the grandi and number of d-<lectons a =2 or
2p and 5D, 4 for *F and 4F and zero or °$ ems) Ai be separation between ground and the
«xc state and can be obtained fom electronic spect, isthe spin-obit coupling constant and itis
positive for d',d?,d° and d* ions and negative for d°,d",d* and 4? ions. Since À is positive for
41,42, and ins and negative for, a? eS anda ions, bel, he pin -obit coupling gives
low values ofmagneti moments for fist se of complexes and higher val of magnetic moment forthe
Ir.
‘Thehigh spin octahedral complex of Mn?* (d°), say, [Mo(H30)41°* for which ground stat is © Ay,
Has no excited state of sme spin maplity as kat ofthe ground state. Therefore, ming of ground ste
ith any ofthe excited states du o spin-orbit coupling i copas Ths cs oral contribution
toys det pin obit coupling Therefore, eis same 2 150, Aleman, since the ground sae
SA ases fom °S tr for which =0, thereto, og. same sj,
The ground state fr low spin complex of deal in i aso A but al letrons are paired and
enc the complex is diamagnetic,
High Spin-Low Spin Equilibria
Octhedral complexes of 4, 4°, d and d? of fist series transition metal ions can either be high
spinor low spin depending onthe magnitudeofligand ld spliting A, nd pairing energy, P. When the
magnitude of y has an intermediate value in such away tha the two complexes (LS and HS) have same
energy, th two complexes can exist in equilibrium. The low spin and high spin complexes of a metal
‘cation canbe distinguished by measurement of either magnetic suscetibiliy or magnetic moments. For
igh spin complexes 4g < P and fr low spin complexes A > P. Ihe difference in energy between
and Pi smallor negligible, the low spin and high spin can coexist in equilibrium. Consider the low spin,
In the similar way, the tetrahedral complexes with the following configurtions have orbital
coatibuions
PEMA), arf) and P(e)
‘Table 6.1 : Experimental and Calculated Values of Magnetic Moments for
‘Some High Spin and Low Spin Octahedral Complexes,
el
we 0 à hs in | = =
ve 2 2 jamsass|2e |- a 2
ar 3 3 130300 [38 . |- a i
ar 4 a |475-490|490 12 320-330 | 283
ma? s 5 jss-o|se | 180-210 | 1.73
Ret 5 s Iso |sn |i 2025 [1
Re 6 a [s10-s70 450. Jo = =
ct 7 1430-520 (388 + |1 18 13
wi 8 2 283528 | = =
art 9 1 Jura lim |- = es
In ger, ba contribution is posible incomplete in which the ground state of metal ion is
ecrnically triply degenerate (€, 234). On te other hand the orbital contribution is not posible in
‘complexes in which he ground tte of metal fn ¡electronica on degene ox doubly degenerate
(eg dag ory)
Alia sted complex of (5, mei onhave cst an experimen magna
moments of 3.87 and 52 BLM. respectively: The higher value of experimental magnetic moment is
expected becas ofthe rl contin, Friera enmle(CaCa]™ (13) the calculated
and experimental magnetic moments are 3.87 and 4. B M. respectively. In is case the higher value of
‘xperimentaf magnetic moment isnot due 0 orbital contiaton. Although in most of the complexes
with or E ground state the quenching ofthe orbital cotibuton is expected o be complete and the
experimental magnetic moment is very close o spin ocly magnetic moment and is temperature
independent However in some complexes there isthe deviation ofthe experimental magnetic moment
from the spin only magnetic omen. This due to the temperature independent paramagnetis,
TR inswcheasesthefistexcited stat, fof same spin mol asthe ground ste) mixes up with À
or E ground sate doe to spin omit coupling. For those complex in which spin-orbit coupling is
signifiant, the following equation is used to calcule
a
sus (1-2
‘Where isaconstant which depends upon the grandi and number of d-<lectons a =2 or
2p and 5D, 4 for *F and 4F and zero or °$ ems) Ai be separation between ground and the
«xc state and can be obtained fom electronic spect, isthe spin-obit coupling constant and itis
positive for d',d?,d° and d* ions and negative for d°,d",d* and 4? ions. Since À is positive for
41,42, and ins and negative for, a? eS anda ions, bel, he pin -obit coupling gives
low values ofmagneti moments for fist se of complexes and higher val of magnetic moment forthe
Ir.
‘Thehigh spin octahedral complex of Mn?* (d°), say, [Mo(H30)41°* for which ground stat is © Ay,
Has no excited state of sme spin maplity as kat ofthe ground state. Therefore, ming of ground ste
ith any ofthe excited states du o spin-orbit coupling i copas Ths cs oral contribution
toys det pin obit coupling Therefore, eis same 2 150, Aleman, since the ground sae
SA ases fom °S tr for which =0, thereto, og. same sj,
The ground state fr low spin complex of deal in i aso A but al letrons are paired and
enc the complex is diamagnetic,
High Spin-Low Spin Equilibria
Octhedral complexes of 4, 4°, d and d? of fist series transition metal ions can either be high
spinor low spin depending onthe magnitudeofligand ld spliting A, nd pairing energy, P. When the
magnitude of y has an intermediate value in such away tha the two complexes (LS and HS) have same
energy, th two complexes can exist in equilibrium. The low spin and high spin complexes of a metal
‘cation canbe distinguished by measurement of either magnetic suscetibiliy or magnetic moments. For
igh spin complexes 4g < P and fr low spin complexes A > P. Ihe difference in energy between
and Pi smallor negligible, the low spin and high spin can coexist in equilibrium. Consider the low spin,
{(Fe(CN)g]* (with ground state Ag) and high spn comple, [Pe ]* (with ground state tem a)
of Fe on, The Tanabo-Sugano diagram of low spn hig, pin complexes shows that eiergiesof! Aig
and $T ground states becomes comparable (Figure 6.6) at or nea the cross over point. At or near the
‘rss over pont these two states eoexistin equilibra
‘The most important example ilustrating these effects is [Fofhen) (NCS)2} At high temperature
this complex exists a high spin with fourunpaiedelecrons. When the temperature is decreased, here
decrease in magnetic moment at 174 K (Figure 6.7) and the complex becomes low spin. This
indicates that at 174 K[Fe(phen)» (NCS) exist as both high spin and low spin
s
4
Magnets moment (BA) —
160 200" 300" do 500|
Tempero) —
1. The magnetic behaviour of complexes (Co(H20)6P and [CoH )g]* ae.
respectively
2. The magnetic moments of (CHI) and (CNE) ar „nad
respectively
3. A paramagnetic substance shows at fromage below
44 The magnetic moment or (Co) i 543 BM. This high value of ‘magnetic moment than
expected is due to
$. The comple [eS pil a un te emp of
vb
6. The compounds: a and MnO} are …
7. he RrlCOF Fe su than (CoC)
8. Paragua suscepti à. e abso eet.
9. Magnetic ey ‘of ferromagnetic and anti-ferromagnetic substances can be calculated! by
10, The paramagnetic substances are. inthe magnetic field
11. Themagnecosuscepúbiiy ia mesure of extent to whcha substance tends tobe
and respectively,
[Ans. 1. diamagnetic, paramagnetic 2. 20,387 BM.
3. Net's temperature 4. orbital contribution
5. I76K 6, feromagnetic,antiferromagnetio
7. less 8. inversely proportional
9. Curie-Weiss 10. acid
1. mapnetized }
1. The magnetic moment ofan octabedral Co (4) complex is 4.0 1p. The electronic configuration of
the complex is
; sa
tet wie
On Ong
2. A tension metal complex shows a magnetic moment of 5.20 B.M. at room temperature, The
tbe of unpaicedelecrons on th meli:
@3 oye
(95 (92
of Fe on, The Tanabo-Sugano diagram of low spn hig, pin complexes shows that eiergiesof! Aig
and $T ground states becomes comparable (Figure 6.6) at or nea the cross over point. At or near the
‘rss over pont these two states eoexistin equilibra
‘The most important example ilustrating these effects is [Fofhen) (NCS)2} At high temperature
this complex exists a high spin with fourunpaiedelecrons. When the temperature is decreased, here
decrease in magnetic moment at 174 K (Figure 6.7) and the complex becomes low spin. This
indicates that at 174 K[Fe(phen)» (NCS) exist as both high spin and low spin
s
4
Magnets moment (BA) —
160 200" 300" do 500|
Tempero) —
1. The magnetic behaviour of complexes (Co(H20)6P and [CoH )g]* ae.
respectively
2. The magnetic moments of (CHI) and (CNE) ar „nad
respectively
3. A paramagnetic substance shows at fromage below
44 The magnetic moment or (Co) i 543 BM. This high value of ‘magnetic moment than
expected is due to
$. The comple [eS pil a un te emp of
vb
6. The compounds: a and MnO} are …
7. he RrlCOF Fe su than (CoC)
8. Paragua suscepti à. e abso eet.
9. Magnetic ey ‘of ferromagnetic and anti-ferromagnetic substances can be calculated! by
10, The paramagnetic substances are. inthe magnetic field
11. Themagnecosuscepúbiiy ia mesure of extent to whcha substance tends tobe
and respectively,
[Ans. 1. diamagnetic, paramagnetic 2. 20,387 BM.
3. Net's temperature 4. orbital contribution
5. I76K 6, feromagnetic,antiferromagnetio
7. less 8. inversely proportional
9. Curie-Weiss 10. acid
1. mapnetized }
1. The magnetic moment ofan octabedral Co (4) complex is 4.0 1p. The electronic configuration of
the complex is
; sa
tet wie
On Ong
2. A tension metal complex shows a magnetic moment of 5.20 B.M. at room temperature, The
tbe of unpaicedelecrons on th meli:
@3 oye
(95 (92
3. The expected spinanly mag momets fos [Fo(CN)e]'" and Fer)” epetvely are:
(9 11308 LBM (0) 173 and 592 BM.
(©) 00 and 1.73B. (00 and 5,92 BM—~
(2) The metal ion which is most likely to show the low spin-high spin equilibria ns complexes has
the electronic configuration
od was
N or we
5. The effective mage moment is maximum fr;
(a) KaMn(CN) 5, G}K2MrO4
€) KaMnCle 7 @KMn0, ©
6. The complex wih spin-oely magnetic moment of 4.9 BM. i:
re OFEN"
OF MELO"
2. The compound tranFefo Phen)» (NCS)2] las a magnetic moment of 0.65 BM. a 80 K,
increasing with temperature to 52 BM. at 300 K. The correct statement is:
(9 These existe equim betwee high sin and low spin complexes.
(i) Thec i igiiant charge in UV-visible spectrum wth iemperature
(Gi) Number of wpaized les at 80K and 300K are 1 and repectivel.
Gi) Number of unpre los at 80K and 300K ar zero and respectively.
(a) Only D (0) Only (ii) and (iv)
(9 Oaly ©, (and) A) Only), Gi) and (i)
The zero magnetic mome o ectaadral Ko NiFg is due o
(a) low spin a6 NV) complex
(0) low spin dŸ Nid) complex Er
(©) High spin d® Niftcompler Az)
(4) high spin dS NiQV) complex
In tetrahedral geometry, which an ofthe following sts of electronic configurations wil have
Orbit coton to the magnetic moment?
PF asda and? A £
NS Waadt
Ob dd ma?
mdd
10. The experimental magnetic moment of Ks[Fe(CN))is2. up and satbutabl to the:
(2) spinonly vaıeofalowapinfe
©) pico value of high-spin Fe
{api e with orbital cambio
(@ high-spin Fe with xb comio
Ce
11. The magnetic moment of {RH1O)6 ?* corresponds tothe presence of:
(a) four uopaired electrons (0) tree unpaited electrons
£) two unpre elos défi unpare cas
IE) nenn
5 WRCANCH] OSEA)
1 rap CORE]
13. The complexes at woul show paramagnetic behaviours
MOI SEL
(©) (Cu(l, 10- phenantroline)]* FACH)
14. The spin-only magnetic moment (in B.M) value of [FeFs]" and [Co(CN)s(HO))™
Bout. an
ss (c) 4:47 and 1.73 (d) 5.92 and 3.87
45) Which two among [Fe(ON)e]" [Feks]”", (Cutbpy)2]?* and (Mafucc);] (eae = ace
acetonate anion) show the same spin-only magnetic moment?
ROH)" and [Fes]
ON marc Pa À HE
(gkfFekis]?” and (Maacae)y}
{@){Culbpy 2)” andas]
16. Consider the two complexes (4){Ni(H;0).]°* and (2) [NING Je], the ight statements:
(a) Complex (4) is diamagretic and complex (8) is paramagnetic.
49) Complex (4) is paramagnetic and complex (8) is diamagnetic.
(6) Both are paramagncie
(6) Bosh ae diamagnetic.
17. The scl magnetic mamentsbowsa large deviation fom the spin-on forma in he cas of:
on" ve
ce" lam"
48) of the following metal ins, which has hc largest magnetic moment in its low spin octahedral
I complex? 5
yy are
CS Ye get ET
19. (sent) ocCr”" in igh spin andlowr-pincomplens should be
(0 490 B.M.and 223 BM, respectively 7
(©) 490 B.M, fo both
(6) 1.73 BM, and2.83 BM, respctively
(8) 4S0B.M. and 1.73 BM. respectively
(9 11308 LBM (0) 173 and 592 BM.
(©) 00 and 1.73B. (00 and 5,92 BM—~
(2) The metal ion which is most likely to show the low spin-high spin equilibria ns complexes has
the electronic configuration
od was
N or we
5. The effective mage moment is maximum fr;
(a) KaMn(CN) 5, G}K2MrO4
€) KaMnCle 7 @KMn0, ©
6. The complex wih spin-oely magnetic moment of 4.9 BM. i:
re OFEN"
OF MELO"
2. The compound tranFefo Phen)» (NCS)2] las a magnetic moment of 0.65 BM. a 80 K,
increasing with temperature to 52 BM. at 300 K. The correct statement is:
(9 These existe equim betwee high sin and low spin complexes.
(i) Thec i igiiant charge in UV-visible spectrum wth iemperature
(Gi) Number of wpaized les at 80K and 300K are 1 and repectivel.
Gi) Number of unpre los at 80K and 300K ar zero and respectively.
(a) Only D (0) Only (ii) and (iv)
(9 Oaly ©, (and) A) Only), Gi) and (i)
The zero magnetic mome o ectaadral Ko NiFg is due o
(a) low spin a6 NV) complex
(0) low spin dŸ Nid) complex Er
(©) High spin d® Niftcompler Az)
(4) high spin dS NiQV) complex
In tetrahedral geometry, which an ofthe following sts of electronic configurations wil have
Orbit coton to the magnetic moment?
PF asda and? A £
NS Waadt
Ob dd ma?
mdd
10. The experimental magnetic moment of Ks[Fe(CN))is2. up and satbutabl to the:
(2) spinonly vaıeofalowapinfe
©) pico value of high-spin Fe
{api e with orbital cambio
(@ high-spin Fe with xb comio
Ce
11. The magnetic moment of {RH1O)6 ?* corresponds tothe presence of:
(a) four uopaired electrons (0) tree unpaited electrons
£) two unpre elos défi unpare cas
IE) nenn
5 WRCANCH] OSEA)
1 rap CORE]
13. The complexes at woul show paramagnetic behaviours
MOI SEL
(©) (Cu(l, 10- phenantroline)]* FACH)
14. The spin-only magnetic moment (in B.M) value of [FeFs]" and [Co(CN)s(HO))™
Bout. an
ss (c) 4:47 and 1.73 (d) 5.92 and 3.87
45) Which two among [Fe(ON)e]" [Feks]”", (Cutbpy)2]?* and (Mafucc);] (eae = ace
acetonate anion) show the same spin-only magnetic moment?
ROH)" and [Fes]
ON marc Pa À HE
(gkfFekis]?” and (Maacae)y}
{@){Culbpy 2)” andas]
16. Consider the two complexes (4){Ni(H;0).]°* and (2) [NING Je], the ight statements:
(a) Complex (4) is diamagretic and complex (8) is paramagnetic.
49) Complex (4) is paramagnetic and complex (8) is diamagnetic.
(6) Both are paramagncie
(6) Bosh ae diamagnetic.
17. The scl magnetic mamentsbowsa large deviation fom the spin-on forma in he cas of:
on" ve
ce" lam"
48) of the following metal ins, which has hc largest magnetic moment in its low spin octahedral
I complex? 5
yy are
CS Ye get ET
19. (sent) ocCr”" in igh spin andlowr-pincomplens should be
(0 490 B.M.and 223 BM, respectively 7
(©) 490 B.M, fo both
(6) 1.73 BM, and2.83 BM, respctively
(8) 4S0B.M. and 1.73 BM. respectively
| Sn,
Ti aie emi wenn:
oe (ieee
Sond one
21. The plotoPgT ve. data of an ideal paramagnetie sample wil
a) pass through origin
(0) be parallel to Taxis 7
(pct
(para rate
22. Magnetic moment of [RHF] in BM. is:
win (ase
Oxo (238
The species it highest magnetic moment (pin nt valu) à à
vat EC
(91CANO Je o NEFA
24. ThemapsemgentoC"™ in quar plana coles
(a) BB. (0) 3.87 B.M.
(9 487B.M. (4) 5.87 BM.
25, Red B-keoerlte complex of NKI) is diamagnetic. The red complex tus bluisegreen in the
presence of water or amines and becomes paramagnetic. Which of the following structures
formed during the reaction ?
(@) Terahedeal (©) Square planar
(©) Octahedral (9) Dodecahedral
26. The pot off versus T {where is molar magnetic susceptibility and Tis be temperature) for a
paramagnetic complex which strictly follows Curie équation is
o IN
on
10. 20 3H 4 50 6H 26
am 20 HMM HH Re BH KY
50 50 MO BHO BH 20 10
20 BO “0 MO BH KO
1. Explein he lowing:
() The magnetic moments for octahedral and tetrahedral complexes of Ni?* jon are2.9-3.9 B.
1044.1 BM. epetvely whereas square planar complexes ar damage,
NICH" is paramagnetic whereas [PACI4 }?- and {PtClg > are diamagnetic.
(The oculetnl complexes of a, 42, d® (HS) and ES) configuration have orbit
conato o magnetic moment
(040) ishighly paramagnetic yet its not ferromagnetic.
9 Ky (Cais paramagnetic whereas K Nis diamagnetic
(i) Cx" ions ar colour and paramagnetic whereas Za ions are colourless and diamagnetic.
(vi) The compound NCI, (PPh3)2} is ved crsalino and iamagnetic. On heating, thi
compounds converted to green form of magnetic moment 3.208.
‘ip The magnetic moment of (NU) V(SO,)2-12H0is 28 BLM anit gives te absorptio
bands in is electronic spectra at 17200 cm, 25700 cm" and 36000 cen”! in aqueou!
solution.
x) The spin only magnetic moments of K 3{Fe(OX )} Jand K{Ru(OX 5 Jare 5.91 BM, and 1.7
BM respectively. (At. no. of Fe and Ru are 26 and 44 respectively)
2, What change in magnetic properties (any) can be expected when NO} ligands infCo(NO2 }
are replaced by CI” ligands ?
Ti aie emi wenn:
oe (ieee
Sond one
21. The plotoPgT ve. data of an ideal paramagnetie sample wil
a) pass through origin
(0) be parallel to Taxis 7
(pct
(para rate
22. Magnetic moment of [RHF] in BM. is:
win (ase
Oxo (238
The species it highest magnetic moment (pin nt valu) à à
vat EC
(91CANO Je o NEFA
24. ThemapsemgentoC"™ in quar plana coles
(a) BB. (0) 3.87 B.M.
(9 487B.M. (4) 5.87 BM.
25, Red B-keoerlte complex of NKI) is diamagnetic. The red complex tus bluisegreen in the
presence of water or amines and becomes paramagnetic. Which of the following structures
formed during the reaction ?
(@) Terahedeal (©) Square planar
(©) Octahedral (9) Dodecahedral
26. The pot off versus T {where is molar magnetic susceptibility and Tis be temperature) for a
paramagnetic complex which strictly follows Curie équation is
o IN
on
10. 20 3H 4 50 6H 26
am 20 HMM HH Re BH KY
50 50 MO BHO BH 20 10
20 BO “0 MO BH KO
1. Explein he lowing:
() The magnetic moments for octahedral and tetrahedral complexes of Ni?* jon are2.9-3.9 B.
1044.1 BM. epetvely whereas square planar complexes ar damage,
NICH" is paramagnetic whereas [PACI4 }?- and {PtClg > are diamagnetic.
(The oculetnl complexes of a, 42, d® (HS) and ES) configuration have orbit
conato o magnetic moment
(040) ishighly paramagnetic yet its not ferromagnetic.
9 Ky (Cais paramagnetic whereas K Nis diamagnetic
(i) Cx" ions ar colour and paramagnetic whereas Za ions are colourless and diamagnetic.
(vi) The compound NCI, (PPh3)2} is ved crsalino and iamagnetic. On heating, thi
compounds converted to green form of magnetic moment 3.208.
‘ip The magnetic moment of (NU) V(SO,)2-12H0is 28 BLM anit gives te absorptio
bands in is electronic spectra at 17200 cm, 25700 cm" and 36000 cen”! in aqueou!
solution.
x) The spin only magnetic moments of K 3{Fe(OX )} Jand K{Ru(OX 5 Jare 5.91 BM, and 1.7
BM respectively. (At. no. of Fe and Ru are 26 and 44 respectively)
2, What change in magnetic properties (any) can be expected when NO} ligands infCo(NO2 }
are replaced by CI” ligands ?
ing be cyst Geld tO Health magi moments nes of BM. ofthe fllowing
complexes
© (coke). O) uel (©) [Copstis).
crag) e
Using crystal field ee
[Ni AP and (CO)
cose gi oui Parma) fr an cal N complex exhibiting spin
allowed ~ dbardat 1075020" 17500em and 2200en respectively. The experimentally
detemined magner moments 32 EM.
«gent oF 4 transition elements comeponds opin only value. Explain
[> is wore paramagneti than(Fe(CN)5]”. Explain on the basis of CFT.
a ofl Fe(pea) (CS)? vais with temperature The magnetic moments at
The magnetic moment
ago and sox an 498-2040 BM, respectively, Wi dicos configurations of Feat
ive reason forthe observed change in the magnetic moment
Ts (0 ICO), (0) [RICO], (0)
explain the structure and magnetic properties of [NiCla]”,
‘The magnetic mo
The complex [Fe
both empero and
(phen = 1, 10 pheanibroline)
aaa
* Sailiy ofa complex compound is asigned to be its existence in aqucous solution with respect to
it bond dissociation energy, Gibbs free energy, standard electrode potential oc pH ofthe solution and
of
rat constant or activation energy for substitution reactions, On account ofthese parameters stabil
complexes is oo types.
‘Thennodyoamic stability and
Kinetic stability
THERMODYNAMIC STABILITY,
Theodor abil of complex rest tendency et unde eq
na mad weanay nt termod mame Sii af acomplei te mesure oftendeacy os
meine om a arcas comple o, mode bys dei ett mtb and
Bond ape The hemodynane Bay ofacompexs vet omo conste also alle
stil mat which i Ce equlbrum cnt o comple o omaton)
1a ¡oral camplees ar not prepared Som cir compren input phase bt se are
‘prepared in aqueous solution. In aqueous Solution a metal cation gets hydrated to give, [M(H20),J%
comple o. Wen igand replies water molle fom aqu complex io, a now complex ion i
feed adn lic cable ho our mes
K/,
IMGLO), 1" +L = (MALO). LI" +H20 0)
‘Where xisthe numberof water molecules, is the oxidation nonberof he metal cation and isthe
‘ral and monodentate ligand, For simplicity, the above reaction canbe writen in generalized formas,
given below
Kr,
M+L =2 ML di
‘The eqliriu constant of the reaction is given by
Concentration of HO is constant in dilute sohtion ofthe metal complex and it i incorporated
into K . The water molecule which enters the bulk solution doesnot affect the equilibrium constant.
complexes
© (coke). O) uel (©) [Copstis).
crag) e
Using crystal field ee
[Ni AP and (CO)
cose gi oui Parma) fr an cal N complex exhibiting spin
allowed ~ dbardat 1075020" 17500em and 2200en respectively. The experimentally
detemined magner moments 32 EM.
«gent oF 4 transition elements comeponds opin only value. Explain
[> is wore paramagneti than(Fe(CN)5]”. Explain on the basis of CFT.
a ofl Fe(pea) (CS)? vais with temperature The magnetic moments at
The magnetic moment
ago and sox an 498-2040 BM, respectively, Wi dicos configurations of Feat
ive reason forthe observed change in the magnetic moment
Ts (0 ICO), (0) [RICO], (0)
explain the structure and magnetic properties of [NiCla]”,
‘The magnetic mo
The complex [Fe
both empero and
(phen = 1, 10 pheanibroline)
aaa
* Sailiy ofa complex compound is asigned to be its existence in aqucous solution with respect to
it bond dissociation energy, Gibbs free energy, standard electrode potential oc pH ofthe solution and
of
rat constant or activation energy for substitution reactions, On account ofthese parameters stabil
complexes is oo types.
‘Thennodyoamic stability and
Kinetic stability
THERMODYNAMIC STABILITY,
Theodor abil of complex rest tendency et unde eq
na mad weanay nt termod mame Sii af acomplei te mesure oftendeacy os
meine om a arcas comple o, mode bys dei ett mtb and
Bond ape The hemodynane Bay ofacompexs vet omo conste also alle
stil mat which i Ce equlbrum cnt o comple o omaton)
1a ¡oral camplees ar not prepared Som cir compren input phase bt se are
‘prepared in aqueous solution. In aqueous Solution a metal cation gets hydrated to give, [M(H20),J%
comple o. Wen igand replies water molle fom aqu complex io, a now complex ion i
feed adn lic cable ho our mes
K/,
IMGLO), 1" +L = (MALO). LI" +H20 0)
‘Where xisthe numberof water molecules, is the oxidation nonberof he metal cation and isthe
‘ral and monodentate ligand, For simplicity, the above reaction canbe writen in generalized formas,
given below
Kr,
M+L =2 ML di
‘The eqliriu constant of the reaction is given by
Concentration of HO is constant in dilute sohtion ofthe metal complex and it i incorporated
into K . The water molecule which enters the bulk solution doesnot affect the equilibrium constant.
Higher the value of Ky more will be the sably ofthe complex formed. A high value of
equilibrium constant (£ y > 10) indicts ta at unn, activi of complex ML is larger than the
product of activities of M and L. Thus, arg value of Ky indicates that ligand L binds to the metal ion
mare strongly than HzOand hence Lis a tngerligand han HO. Kis ess than 10, then gtd Lis
‘weaker than 0. This, stability constantisused a measur of thermodynamic stability comes,
‘The formation constant (K y) is related 10 Ih suadard Gibbs free energy change and standard
ectode potential according to following elton
—ATtoKy 69
and ACP FE - ©
and RTK y = FE" 6)
Since AG is a thennodynaric propery us formation constant isthe mesuré o tennodyan
stabil.
‘The equations (iv), (4) and (vi) indicate that te thermodynamic stability of a complex can be
‘measured in terms of formation constant, AG" and standard electrode potential. A high negative value of
AAG# (ar a high positive value of £9) inicats thatthe postion of equilibrium favous the prou
(complex) ie high negative value of AG indicates thatthe complex formed wil be more stable
Stepwise Formation of Complex and Stepwise Formation Constants
‘The extent to which a meal cation combine wit ligands to form a complex ion is expressed in
fers of formacion constant. A complex is fomed by mation of water molecules by fer song,
ligands om aquated metal ion nan aqueos ain. When more than one water moecalof dre
mea cation, [M(H,0),]" are replaced by anor neural and monodentate ligand L tea it is
assumed that is may occur in eves steps and each pischaracterized by lts individual equim
constat called a stepwise formation conan (or steps sail constants). Fora general ae ofthe
formation of complex re an aquated metal cation [M(H¿0), ]"* and monodentate ligand L,
‘there will ben conseciive seps and # stepwise formation constants,
SLM k= 2
[10]
ey tis „[ML2]
Melun à Rte ey
B
ante Ñ {ML}
Man: Ki “
N 5 ken Ma]
ML, +L My o
Men SM Me)
au
Where Ki, Ko 3»... ar he stepwise fomation constants or stepwise sabi constants
Vier a is overall formation constant o ver sabi, constant.
‘The formation of complexes ML, MLz ML... ML, may ao be expressed by the following
steps and equilibrium constants, B2,B5, fi, eapeively.
BRIG of Complene ing Res
i
wot
(Myr
unta py Ba
bod H IMIILF
ML ML, Pl e
MIL
Were 2,3, Ps arch equilibrium constants called as overall or cumutaive) ration.
tant or over ab constants.
Relationship between Ki, Ka.
Consider te expression fs
y= Mal o
a.
On mutig bh aumetrand eomit y (LEML a he range
N} M)
isa Dita)
ML) (Mla) DM)
LM M)
| a -@
j Therefore, y Ko Kg ciclo 4)
ad loge = log +g og + og,
Cp 7 Eguation(5) indicates thatthe overall formation constant ($) is equal tothe produc ofthe stepwise
formation constants Ky, KK, ... £ . Also equation (5) indicates thatthe formation ofa complex
takes place in various sepwvise equa,
“The inverse of the formation constant (Kis called the dissociation constant (Kg) or insti
constant of the complex,
‘The dissociation constant gives a measure ofthe extent to which the equiibrium representing the
| formation of a complex listo the right.
equilibrium constant (£ y > 10) indicts ta at unn, activi of complex ML is larger than the
product of activities of M and L. Thus, arg value of Ky indicates that ligand L binds to the metal ion
mare strongly than HzOand hence Lis a tngerligand han HO. Kis ess than 10, then gtd Lis
‘weaker than 0. This, stability constantisused a measur of thermodynamic stability comes,
‘The formation constant (K y) is related 10 Ih suadard Gibbs free energy change and standard
ectode potential according to following elton
—ATtoKy 69
and ACP FE - ©
and RTK y = FE" 6)
Since AG is a thennodynaric propery us formation constant isthe mesuré o tennodyan
stabil.
‘The equations (iv), (4) and (vi) indicate that te thermodynamic stability of a complex can be
‘measured in terms of formation constant, AG" and standard electrode potential. A high negative value of
AAG# (ar a high positive value of £9) inicats thatthe postion of equilibrium favous the prou
(complex) ie high negative value of AG indicates thatthe complex formed wil be more stable
Stepwise Formation of Complex and Stepwise Formation Constants
‘The extent to which a meal cation combine wit ligands to form a complex ion is expressed in
fers of formacion constant. A complex is fomed by mation of water molecules by fer song,
ligands om aquated metal ion nan aqueos ain. When more than one water moecalof dre
mea cation, [M(H,0),]" are replaced by anor neural and monodentate ligand L tea it is
assumed that is may occur in eves steps and each pischaracterized by lts individual equim
constat called a stepwise formation conan (or steps sail constants). Fora general ae ofthe
formation of complex re an aquated metal cation [M(H¿0), ]"* and monodentate ligand L,
‘there will ben conseciive seps and # stepwise formation constants,
SLM k= 2
[10]
ey tis „[ML2]
Melun à Rte ey
B
ante Ñ {ML}
Man: Ki “
N 5 ken Ma]
ML, +L My o
Men SM Me)
au
Where Ki, Ko 3»... ar he stepwise fomation constants or stepwise sabi constants
Vier a is overall formation constant o ver sabi, constant.
‘The formation of complexes ML, MLz ML... ML, may ao be expressed by the following
steps and equilibrium constants, B2,B5, fi, eapeively.
BRIG of Complene ing Res
i
wot
(Myr
unta py Ba
bod H IMIILF
ML ML, Pl e
MIL
Were 2,3, Ps arch equilibrium constants called as overall or cumutaive) ration.
tant or over ab constants.
Relationship between Ki, Ka.
Consider te expression fs
y= Mal o
a.
On mutig bh aumetrand eomit y (LEML a he range
N} M)
isa Dita)
ML) (Mla) DM)
LM M)
| a -@
j Therefore, y Ko Kg ciclo 4)
ad loge = log +g og + og,
Cp 7 Eguation(5) indicates thatthe overall formation constant ($) is equal tothe produc ofthe stepwise
formation constants Ky, KK, ... £ . Also equation (5) indicates thatthe formation ofa complex
takes place in various sepwvise equa,
“The inverse of the formation constant (Kis called the dissociation constant (Kg) or insti
constant of the complex,
‘The dissociation constant gives a measure ofthe extent to which the equiibrium representing the
| formation of a complex listo the right.
‚Trends in Stepwise (or Successive) Formation Constants
‘With few exception, tis commonly observed tha te magnitude of stpvise formation constant
decreases steadily G0m KK, .
LD Ka > Ky >. Ka > Ka
‘This trend is illustrated by : (D) 09?" — NH3 complex and (ii) CA?” — CN” complexes.
o CA? + Ns == [CA NH Jf :
CAO) + Nis Ca)
NE;
TE NEIN; Ku =10°
Ba =Kı-K2-Ky-Ky =10% 192 9444 19993
out
10) CA? CN" [caccn)]*
EUCH] N Can) ;
[CA(CN)2)+CN OMC) É
[EXEN)sT + ON [CH(CN) JA ;
De 210° 40512 4988549253
‚ns
Te end deat al af is forma const fon Kos e to
ar hymne ra höeb:
ca pr of rm oe
He ae reed a ee
Tigands (iv) stlstical con. =—
“However, in some cass i is found that Kya > K becaize of unusual structure change and
caba stone sucre, huge O othe aration
une in clon ones te ans CES ol somes wim a ot
E wil be mor table and the equilibrium constant for that cmplex formation will be high
fami cane mn Be compe ann eon
‘of [CABta]?” complex with Br” exhibit four stepwise equilibrium or stepwise fometion constants
Fra ‘The order of stepwise formation constints is observed as folows
D > Ka > E Ka oct contra to; > Ky > Ky > Ka
eq compl of mest ofthe M2" ions are octahedral whereas he halo complexes of Cd ion
general tea Te reactions othe fomation (CAB are:
A
o [CA(H¿0)s]?* + Be” ==> [C4(H¿0)5 Br)" + H20
SE.
x
(CHO) 4B} Br SCHON Bel +20
(Ca; 0)3 Br + Be” [CAB] +310
‚ichs ep ee FLO alo rm 5
structural and electron configuration change and this Ky > Kg. = Le
Further consider another example of formation of{Fe(bp¥)°* fom aqueaus solution ofFe™* on.
‘The formation of fFefopy)s ** complex ion with bipytidyl takes place in theee steps and order of
stepwise fomation contantsis Ky > Kz < Ks which is contrary to K > Ka > Ks. Thereacton forthe
formation (Fe) ae: —
Ka en
LFLO) P* + bey == [Feltl20)4(opy))?* +2420
x
[Feit20) ny)" +bpy == [Fe(H20)2(opy)a 1?" +220 Pr
a
[Fe(H0)2(bp5)2J+ by === (Fetbpy)s F* +220
he two complexes [Fo(H0)«(bpy)]?" and [Fe(H20)2(bpy)2]"* are high spin due to the
rence of weak HzOligenis having, e electronic configuration wih CFSE 0-04 Aa
‘The complex (Fe(tpy)3 formed in last step is low spin due to the presence of only strong.
"ipyriy ligands This complex hve clconi configuration Sef with CFSE of~24 A. Tae,
there change in elecunic configuration an
rease in CFSE. Hence, Ks > Kp,
FACTORS AFFECTING STABILITY OF COMPLEXES.
“The factors which determine the stability of complexes are:
(1) Nature ofthe Central Metal lon (0) Nature ofthe Ligands
~ ©) The Chelate Etc ~ (4) Macrocycle Effect
(5) Resonance Effect (6) Steric fect or Stesc Hindance
(1) Nature of the Central Metal fon.
Variations inthe stabiles (Le, stability constants) fr a series of complexes af metals ions
‘with a common set of igands.
€) Charge on Meta Cation In general a metal cation in higher oxidation state form more sable
complexes than hat of in lower oxidation states with a given igand like A” orN or 10. However
there are few exceptions with ligands such as CO, PME, o-phenanthroline, ipytidy, CN whic
form more stable complexes with meals in lower oxidation sates. These ligands have vacané x*
‘molecular orbitals 5 scconimaation f one pair‘of electrons donated by metal atom o cation and
hence for rbackbonding TheeectoarichCN™ isnot only a poor x-acceptorbotisalsoa good-donor
and, therefore, forms complenes with meal toms in higher oxidation se.
‘With few exception, tis commonly observed tha te magnitude of stpvise formation constant
decreases steadily G0m KK, .
LD Ka > Ky >. Ka > Ka
‘This trend is illustrated by : (D) 09?" — NH3 complex and (ii) CA?” — CN” complexes.
o CA? + Ns == [CA NH Jf :
CAO) + Nis Ca)
NE;
TE NEIN; Ku =10°
Ba =Kı-K2-Ky-Ky =10% 192 9444 19993
out
10) CA? CN" [caccn)]*
EUCH] N Can) ;
[CA(CN)2)+CN OMC) É
[EXEN)sT + ON [CH(CN) JA ;
De 210° 40512 4988549253
‚ns
Te end deat al af is forma const fon Kos e to
ar hymne ra höeb:
ca pr of rm oe
He ae reed a ee
Tigands (iv) stlstical con. =—
“However, in some cass i is found that Kya > K becaize of unusual structure change and
caba stone sucre, huge O othe aration
une in clon ones te ans CES ol somes wim a ot
E wil be mor table and the equilibrium constant for that cmplex formation will be high
fami cane mn Be compe ann eon
‘of [CABta]?” complex with Br” exhibit four stepwise equilibrium or stepwise fometion constants
Fra ‘The order of stepwise formation constints is observed as folows
D > Ka > E Ka oct contra to; > Ky > Ky > Ka
eq compl of mest ofthe M2" ions are octahedral whereas he halo complexes of Cd ion
general tea Te reactions othe fomation (CAB are:
A
o [CA(H¿0)s]?* + Be” ==> [C4(H¿0)5 Br)" + H20
SE.
x
(CHO) 4B} Br SCHON Bel +20
(Ca; 0)3 Br + Be” [CAB] +310
‚ichs ep ee FLO alo rm 5
structural and electron configuration change and this Ky > Kg. = Le
Further consider another example of formation of{Fe(bp¥)°* fom aqueaus solution ofFe™* on.
‘The formation of fFefopy)s ** complex ion with bipytidyl takes place in theee steps and order of
stepwise fomation contantsis Ky > Kz < Ks which is contrary to K > Ka > Ks. Thereacton forthe
formation (Fe) ae: —
Ka en
LFLO) P* + bey == [Feltl20)4(opy))?* +2420
x
[Feit20) ny)" +bpy == [Fe(H20)2(opy)a 1?" +220 Pr
a
[Fe(H0)2(bp5)2J+ by === (Fetbpy)s F* +220
he two complexes [Fo(H0)«(bpy)]?" and [Fe(H20)2(bpy)2]"* are high spin due to the
rence of weak HzOligenis having, e electronic configuration wih CFSE 0-04 Aa
‘The complex (Fe(tpy)3 formed in last step is low spin due to the presence of only strong.
"ipyriy ligands This complex hve clconi configuration Sef with CFSE of~24 A. Tae,
there change in elecunic configuration an
rease in CFSE. Hence, Ks > Kp,
FACTORS AFFECTING STABILITY OF COMPLEXES.
“The factors which determine the stability of complexes are:
(1) Nature ofthe Central Metal lon (0) Nature ofthe Ligands
~ ©) The Chelate Etc ~ (4) Macrocycle Effect
(5) Resonance Effect (6) Steric fect or Stesc Hindance
(1) Nature of the Central Metal fon.
Variations inthe stabiles (Le, stability constants) fr a series of complexes af metals ions
‘with a common set of igands.
€) Charge on Meta Cation In general a metal cation in higher oxidation state form more sable
complexes than hat of in lower oxidation states with a given igand like A” orN or 10. However
there are few exceptions with ligands such as CO, PME, o-phenanthroline, ipytidy, CN whic
form more stable complexes with meals in lower oxidation sates. These ligands have vacané x*
‘molecular orbitals 5 scconimaation f one pair‘of electrons donated by metal atom o cation and
hence for rbackbonding TheeectoarichCN™ isnot only a poor x-acceptorbotisalsoa good-donor
and, therefore, forms complenes with meal toms in higher oxidation se.
EERE PEARCE Ce
OS
of the complexes, increases with decrease in size of metal cations. For M?* ions, the. general trend in
Ba <Sr?* < Ca?" < Mg? < Mn?* < Fe®* < Co? < Ni" < Ox >Zu?t
ewan trian
gure ce ag rin cy ea en eee
‘fom Ba?* wo Cu” and then increases to Zn À. The order of sizeof depostive ions is
Ba? > Sr?" > Ca? > Mg?* > Mn > Re?" > Co? > Ni?! > Cu? zu?"
Since size of Zn”* is larger than that of Cu?” ion, therefore, stability oEZa”* complex is lower than
that of Ox?" ion. <
A plot of log Kof complexes of M?* ions with oxalate fons is shown in Figure 7.1. The log Ky
valuesofBa?",Sr?*,Ca?*, Mg?" Mn?* (HS coniplex) and Zo?" complexes liesonatioe because their
wun CRE 20
hp ne on ol aut
Pt RE D ne Ss
oweredin energy (47, while oniyoneeletond à ortitasruisedby an equal unn ee as
pinning tng ml
Ste umes ea ns one
Sond pone
s Dee «
gs
‘
És
Da Sr Ca tg Ma Fe Co M4 Gu zn
AR AA ro sone or ec Ui We
‘The valu of stability constant for octahedral complexes of Ma?“ 1001?" ion increases more
rapid because these ions are additionally stabilized by CFSES in octahedral field Figure 7.1). The
ability of octahedral complexes of Zn?" is lower than that of Cu” ion because ts CFSE is zero and it
fies on te ine representing the sibilities of Ba™",S:**,Ca?*, Mg?" and Ma® ions where CFSE is
also zero. E
(©) Class ‘a? and Class “$? Metals : Ahrland-eal in 1958 have classified dhe metals into three
categories on the basis of ther electron acceptor properties:
(0 Chass “a” meta
i) Cass 6" metals
(i) Borderline metals
19 Clas a? mets: Class a metal ions are characterized by high elecropostive character (Le, low
lectronegativtes), stall size, high oxidation states (43 or higher) and no easily distorted outer
electors. These meal ions form their most stable complexes with ligands favouring eletrosatic
boning. Class a metals form their most stable complexes with the fist elements of group 15, 16 and 17
(eg, NO and)
‘Chass a metal ions include smaller ions from alkali meals, alkane earth metals fighter transition
‘metals in igh oxidation tates (+3 or higher) Class metas are alo called ashard acid or hard metal.
Class metals (ochard metals) are H*, Li", Na”, K*,Be™*,Mg”* Ca Sr™*,aP™*,Ga* In?
sel Inte 63" Mn Fe Co? La Co Ga 254 nt Ta 0", Pat ete
‘The order of stabilities of complexes of clas a” metals with the ligands having the following donor
atoms i as follows
Foch > Br >
0>>S>Se> Te
N>>P>As>Sb
(6) Cass 9 metas = Class °° metals are Less elccopaive, ave relatively ill drbitas and
fo her most stable complexes wi ligands whic, in edition o possess one pais of electrons, have
“pt nota available accommodate electron pairfrom the bals ote metal. Cas metals
form sable complexes with ligands wich have donor atoms from period 3 o subsequend pods: The
‘neal ligand borin these complexes is covalent. The order of stability isthe evento cass a" meals.
“Te inscseinaalbiy of empty d-xbitals in heavier elements favours an erase inability ofthe
‘compictes, Class b metals are also called asso acs or soft metas.
"Theotderof sabilies of complexes with igendshaving he following dono atom sas follows
Freer eB sr
O<<S<Se<Te
N<<P<As< So
‚Furthermore, clas 5° metals form stable complexes with OO, o-phenanthroline, olefins because
hese have vacant x orbital of low ying energy. =>
OS
of the complexes, increases with decrease in size of metal cations. For M?* ions, the. general trend in
Ba <Sr?* < Ca?" < Mg? < Mn?* < Fe®* < Co? < Ni" < Ox >Zu?t
ewan trian
gure ce ag rin cy ea en eee
‘fom Ba?* wo Cu” and then increases to Zn À. The order of sizeof depostive ions is
Ba? > Sr?" > Ca? > Mg?* > Mn > Re?" > Co? > Ni?! > Cu? zu?"
Since size of Zn”* is larger than that of Cu?” ion, therefore, stability oEZa”* complex is lower than
that of Ox?" ion. <
A plot of log Kof complexes of M?* ions with oxalate fons is shown in Figure 7.1. The log Ky
valuesofBa?",Sr?*,Ca?*, Mg?" Mn?* (HS coniplex) and Zo?" complexes liesonatioe because their
wun CRE 20
hp ne on ol aut
Pt RE D ne Ss
oweredin energy (47, while oniyoneeletond à ortitasruisedby an equal unn ee as
pinning tng ml
Ste umes ea ns one
Sond pone
s Dee «
gs
‘
És
Da Sr Ca tg Ma Fe Co M4 Gu zn
AR AA ro sone or ec Ui We
‘The valu of stability constant for octahedral complexes of Ma?“ 1001?" ion increases more
rapid because these ions are additionally stabilized by CFSES in octahedral field Figure 7.1). The
ability of octahedral complexes of Zn?" is lower than that of Cu” ion because ts CFSE is zero and it
fies on te ine representing the sibilities of Ba™",S:**,Ca?*, Mg?" and Ma® ions where CFSE is
also zero. E
(©) Class ‘a? and Class “$? Metals : Ahrland-eal in 1958 have classified dhe metals into three
categories on the basis of ther electron acceptor properties:
(0 Chass “a” meta
i) Cass 6" metals
(i) Borderline metals
19 Clas a? mets: Class a metal ions are characterized by high elecropostive character (Le, low
lectronegativtes), stall size, high oxidation states (43 or higher) and no easily distorted outer
electors. These meal ions form their most stable complexes with ligands favouring eletrosatic
boning. Class a metals form their most stable complexes with the fist elements of group 15, 16 and 17
(eg, NO and)
‘Chass a metal ions include smaller ions from alkali meals, alkane earth metals fighter transition
‘metals in igh oxidation tates (+3 or higher) Class metas are alo called ashard acid or hard metal.
Class metals (ochard metals) are H*, Li", Na”, K*,Be™*,Mg”* Ca Sr™*,aP™*,Ga* In?
sel Inte 63" Mn Fe Co? La Co Ga 254 nt Ta 0", Pat ete
‘The order of stabilities of complexes of clas a” metals with the ligands having the following donor
atoms i as follows
Foch > Br >
0>>S>Se> Te
N>>P>As>Sb
(6) Cass 9 metas = Class °° metals are Less elccopaive, ave relatively ill drbitas and
fo her most stable complexes wi ligands whic, in edition o possess one pais of electrons, have
“pt nota available accommodate electron pairfrom the bals ote metal. Cas metals
form sable complexes with ligands wich have donor atoms from period 3 o subsequend pods: The
‘neal ligand borin these complexes is covalent. The order of stability isthe evento cass a" meals.
“Te inscseinaalbiy of empty d-xbitals in heavier elements favours an erase inability ofthe
‘compictes, Class b metals are also called asso acs or soft metas.
"Theotderof sabilies of complexes with igendshaving he following dono atom sas follows
Freer eB sr
O<<S<Se<Te
N<<P<As< So
‚Furthermore, clas 5° metals form stable complexes with OO, o-phenanthroline, olefins because
hese have vacant x orbital of low ying energy. =>
A eee ee
SIT
Chas? metas are:
go AU TUCO UR GR oT US
(Gi) Borderline Metals; Bordeline metals include dipstve metal ins of Sd-seces which are
han, Fer Co NI, Cul”, Za?*. Fora given igand arder of ability of complexes i
Mate Fe? < Co? < NE Qu > Za Qing Wiliams series)
“According to Pearson hard metals or acid prefer to bicd to hard bass or hard ligand and soft acids
metals prefer to bind to soft bases or ligand. a
2) Nature of Ligands
Basie Character of Ligands: Ta general, mores the base caracer of ligands, mare en it
Sonar is one pair of electrons tothe central meal ion and hence greater isthe stably of de
ex formed. For example, for a given diposiive (M?*)3dseries transition meta ion, order of
manatees er
NH > 10> F
(9 Covalent Character: Higher he covalent characte, igh wile the subi ofthe comple
example onder of stability and covalent characte of amples of A with halogen is
AG > ABB > ARC > Ag
— Decreasing ode of ovalen harter =
— Decreasing order of sbi of complex >
y x- Bonding Capacity of Ligands : The ligando ke CO, CN”, alkenes, phenantvoin,
ney RARAS cc have vacante data o fom x bod ea ees fr le competes
heals
) Dipale Moment of Ligands: For neutral ind, higher the magrtuo of diole moment,
a A ero
ing Nas door atm is
ammonia > ethylamine > diethylamine > triethylamine Y
o A
) The Chelate Effect
Cheling end form more sabi complex an analoges monodentate igands (contain
o same do on) mea ht ch compis ue mar sae ln del pnl
Stop is lets called a chelate fect.
Let us consider the formation of complexes fro hydratd cadmium ion, (CA(H¿0)a 2 with
hylamine (CH3NH2), ethylenediamine (en) and triethylenetetrasmine (tien) ligands. Where
amine CHN) ethylenediamine HN — CH —Ciy - Ni) and tachar
are monodeaiste,
bidentate and tetradentat ligands respectively
[C810 <)°* + ACH; NH = (CACHE Ne" + 440
[Cá(H20):1?* +2en == (Cd(en)2 +4H,0
[CaCH20)< °° + tien == [CACview +420 si)
Structures of[C4(CH3 NHa Je [Caen 1?" and Crem)” ae shown in Figure 7.2
7 ct, — EN af
Gien | MA HN | Né On
D ZN
ein ES act an m? Sn Ct
o o .
pe PAT
ay À
mm, NAO
{ 4 1 as
Lu Sd, A
N l a
Le — Ge w
©
A
[CA(CH¿NH2)4]”* is a non-chelated complex ion whereas [Cáfen), ]?* and {Cd (trier)}?* are
chelated complex ions. Thus, (Cd (CHyNH2)412' is less stable than [Cd (en) ]?* and (Cd (rien). It
is also observed that [CA (rien? is mre stable than (Cd (cao "cheat on. Therefore oder of
“tail ofthese complex ons is:
(CA (CHsNH)4}* <[Cd(ea)a?* <fCa (wien? <—
“The above order of bil of complexes can be explained in vo ways
1. Ineacton : (1) a non-chelated complex ion (C4 (CH NHz)4 1 is formed and there is no net
‘change in the number of molecules and entropy of reaction. On the other hand, in reaction (i) and (ii)
thee an increase in number of molecules and bos tees an increase in entropy of reaction. Since
increase in mumber of molecules in eatin (i) is greater han ht of reaction (i) Therefore, the
‘increase in entopy is greater in action (i tan ect (i). Since bonding in al the above tree
reactions is same, (Le, Cd?—N bond) thus, AH? inall the three reactions is same and negative in sign.
Themodyramially, he stability of comple is expressed interns of AG". Fora stable complex
AGP gaie and large
AG°=a°—rase
Since A" in al thé above thee reactions is same and entopy increases from reaction (to
(Gi) and ths, ee energy change willbe negative in he thee reactions and increases fom reaction () 10
Gt Gin.
SIT
Chas? metas are:
go AU TUCO UR GR oT US
(Gi) Borderline Metals; Bordeline metals include dipstve metal ins of Sd-seces which are
han, Fer Co NI, Cul”, Za?*. Fora given igand arder of ability of complexes i
Mate Fe? < Co? < NE Qu > Za Qing Wiliams series)
“According to Pearson hard metals or acid prefer to bicd to hard bass or hard ligand and soft acids
metals prefer to bind to soft bases or ligand. a
2) Nature of Ligands
Basie Character of Ligands: Ta general, mores the base caracer of ligands, mare en it
Sonar is one pair of electrons tothe central meal ion and hence greater isthe stably of de
ex formed. For example, for a given diposiive (M?*)3dseries transition meta ion, order of
manatees er
NH > 10> F
(9 Covalent Character: Higher he covalent characte, igh wile the subi ofthe comple
example onder of stability and covalent characte of amples of A with halogen is
AG > ABB > ARC > Ag
— Decreasing ode of ovalen harter =
— Decreasing order of sbi of complex >
y x- Bonding Capacity of Ligands : The ligando ke CO, CN”, alkenes, phenantvoin,
ney RARAS cc have vacante data o fom x bod ea ees fr le competes
heals
) Dipale Moment of Ligands: For neutral ind, higher the magrtuo of diole moment,
a A ero
ing Nas door atm is
ammonia > ethylamine > diethylamine > triethylamine Y
o A
) The Chelate Effect
Cheling end form more sabi complex an analoges monodentate igands (contain
o same do on) mea ht ch compis ue mar sae ln del pnl
Stop is lets called a chelate fect.
Let us consider the formation of complexes fro hydratd cadmium ion, (CA(H¿0)a 2 with
hylamine (CH3NH2), ethylenediamine (en) and triethylenetetrasmine (tien) ligands. Where
amine CHN) ethylenediamine HN — CH —Ciy - Ni) and tachar
are monodeaiste,
bidentate and tetradentat ligands respectively
[C810 <)°* + ACH; NH = (CACHE Ne" + 440
[Cá(H20):1?* +2en == (Cd(en)2 +4H,0
[CaCH20)< °° + tien == [CACview +420 si)
Structures of[C4(CH3 NHa Je [Caen 1?" and Crem)” ae shown in Figure 7.2
7 ct, — EN af
Gien | MA HN | Né On
D ZN
ein ES act an m? Sn Ct
o o .
pe PAT
ay À
mm, NAO
{ 4 1 as
Lu Sd, A
N l a
Le — Ge w
©
A
[CA(CH¿NH2)4]”* is a non-chelated complex ion whereas [Cáfen), ]?* and {Cd (trier)}?* are
chelated complex ions. Thus, (Cd (CHyNH2)412' is less stable than [Cd (en) ]?* and (Cd (rien). It
is also observed that [CA (rien? is mre stable than (Cd (cao "cheat on. Therefore oder of
“tail ofthese complex ons is:
(CA (CHsNH)4}* <[Cd(ea)a?* <fCa (wien? <—
“The above order of bil of complexes can be explained in vo ways
1. Ineacton : (1) a non-chelated complex ion (C4 (CH NHz)4 1 is formed and there is no net
‘change in the number of molecules and entropy of reaction. On the other hand, in reaction (i) and (ii)
thee an increase in number of molecules and bos tees an increase in entropy of reaction. Since
increase in mumber of molecules in eatin (i) is greater han ht of reaction (i) Therefore, the
‘increase in entopy is greater in action (i tan ect (i). Since bonding in al the above tree
reactions is same, (Le, Cd?—N bond) thus, AH? inall the three reactions is same and negative in sign.
Themodyramially, he stability of comple is expressed interns of AG". Fora stable complex
AGP gaie and large
AG°=a°—rase
Since A" in al thé above thee reactions is same and entopy increases from reaction (to
(Gi) and ths, ee energy change willbe negative in he thee reactions and increases fom reaction () 10
Gt Gin.
|
i
|
|
|
Si Cor wa Rect Meat Mis ini ET nn
A lugo negative alu of AG? ae te lage vale of sbi constant (A)
because AG's RT InK -
Thus, order of stability ofthe three cómplees a
[CA(CHsNH)4}* < [Oca < (Caltrienyy**
2.CHsNH, en and rin ligands ae competing forthe formation of complexes with CA ion in
es soli the probably fer oft poring othe ist site may be ae ua
‘Once one end fen riens the O4 on, is ia he Second amine group sand ten
isnow gratein vicinity of Cd ion than tbe econdCH NH ligand which free tomoye randomly in
{he solution. Thus, probability of second anne group of en or tin o atach to Cd?" ion is greater han
(hat ofmonodentateigand CH NH. This indicates that formation constants formation of
chelates. aa i
27 Furiher, the third and fourth danoratons (amine groups) of tren are now greater in vicinity whereas
the second en and the monodentate ligand CHsNH are moved freely and randomly inthe solution.
‘Thus, probability of hind and fourth amine groups of tien to attach to C4 ?* ion is greater than that ofen
‘and Cy NH ligands. This indicates that stability of complex increases with the denticiy ofthe ligand
(demticiy of ligands the umber of donoratoms). In othe words, we can ay thatthe chelates in which
one ligand form twa or more ing are more stable han the complex in which one ligand form only one
ring ono ring. Thedepóndenc of sibility of chelates the sie of chelate ings shown in Figure 7.3
gor
In general the chelates having ve membered rings (noludiog the metal) are more stable thn six.
‘membered rings which are in ture more stable than membered rings. Ths, the chelate effect
weakens as the ring size increases. The chelate effect is usually most pronounced for $ - and 6 -
‘membered rings. Smaller rings generally involve excessive rin and become less stable, When the
(tin and rings become much ages, the ekancement o local concentration Le, visi of seo
donor atom of bidetate Ligand) decresses andthe resling complex becomes les stale
Furthermore, othe chelates fomodby dere bidentate ligands of same size withthe sang net
tne stable wll bein he ode, for example oxalate lyinate < ethylenediamine
(4) Macrocyctic Effect
Maerocyli Hands ar luge ig size compounds even without a metal atom present and dx
ligands have several donor toni tir ings to form coordiate bonds with a mel i
hlorgphyl, ke and vito By all on tadette mac
chlaig igands form mor sae compres an analogous monodentae
ligands of appropriate size frm mor stable complexes than chelating gars Ther compe
between a aon-yelc ligand and a moe ligand (e yelie mal dentate Hand) having thes
‘ype of donor toms andthe complex forme by marcel ligand will be moro stable Tis fe
called as mare effet. Cheep ee and vim Bal onan erden (ar od
son mayo eds 4 Quel -
(6) Resonance Etfect
Resonance enhances he sabi ol compis. For example, acetylacetonate anion ligand so
resonance and for stable celtd complex.
Dach at
CH; CH 6 Cy Gt; — € = CH — 0 CH;
Asa resultof resonance the MO tons are equal in lega and sengh
(6) Steric Effect or Steric Hindrance
If à bulky group is either ataced o dor atom or 1 the atom adjacent o don atom,
metabligand bond becomes weak andthe stably of the complex decreases. This effect is called st
effet, For examples
(6) Ethylene diamine (HN CH, —CHa —NH) and N— tetramethyl cisne
(CH) N—CH.—CH,—N(CH)j boar bidentate igands and form cheats with Ni? ion sho
inFigue?a. E
ce ye r oe pe
DES ol,
me | neat Lau
cha, ad AGE
of
a GN a
18 PATES
te De Het ome
no
o an
Te complex (Din es able han) becas in complex (I) the met! groups tache 1 of
Atom cet tri hindeanc nd dern sabi o comple
i
|
|
|
Si Cor wa Rect Meat Mis ini ET nn
A lugo negative alu of AG? ae te lage vale of sbi constant (A)
because AG's RT InK -
Thus, order of stability ofthe three cómplees a
[CA(CHsNH)4}* < [Oca < (Caltrienyy**
2.CHsNH, en and rin ligands ae competing forthe formation of complexes with CA ion in
es soli the probably fer oft poring othe ist site may be ae ua
‘Once one end fen riens the O4 on, is ia he Second amine group sand ten
isnow gratein vicinity of Cd ion than tbe econdCH NH ligand which free tomoye randomly in
{he solution. Thus, probability of second anne group of en or tin o atach to Cd?" ion is greater han
(hat ofmonodentateigand CH NH. This indicates that formation constants formation of
chelates. aa i
27 Furiher, the third and fourth danoratons (amine groups) of tren are now greater in vicinity whereas
the second en and the monodentate ligand CHsNH are moved freely and randomly inthe solution.
‘Thus, probability of hind and fourth amine groups of tien to attach to C4 ?* ion is greater than that ofen
‘and Cy NH ligands. This indicates that stability of complex increases with the denticiy ofthe ligand
(demticiy of ligands the umber of donoratoms). In othe words, we can ay thatthe chelates in which
one ligand form twa or more ing are more stable han the complex in which one ligand form only one
ring ono ring. Thedepóndenc of sibility of chelates the sie of chelate ings shown in Figure 7.3
gor
In general the chelates having ve membered rings (noludiog the metal) are more stable thn six.
‘membered rings which are in ture more stable than membered rings. Ths, the chelate effect
weakens as the ring size increases. The chelate effect is usually most pronounced for $ - and 6 -
‘membered rings. Smaller rings generally involve excessive rin and become less stable, When the
(tin and rings become much ages, the ekancement o local concentration Le, visi of seo
donor atom of bidetate Ligand) decresses andthe resling complex becomes les stale
Furthermore, othe chelates fomodby dere bidentate ligands of same size withthe sang net
tne stable wll bein he ode, for example oxalate lyinate < ethylenediamine
(4) Macrocyctic Effect
Maerocyli Hands ar luge ig size compounds even without a metal atom present and dx
ligands have several donor toni tir ings to form coordiate bonds with a mel i
hlorgphyl, ke and vito By all on tadette mac
chlaig igands form mor sae compres an analogous monodentae
ligands of appropriate size frm mor stable complexes than chelating gars Ther compe
between a aon-yelc ligand and a moe ligand (e yelie mal dentate Hand) having thes
‘ype of donor toms andthe complex forme by marcel ligand will be moro stable Tis fe
called as mare effet. Cheep ee and vim Bal onan erden (ar od
son mayo eds 4 Quel -
(6) Resonance Etfect
Resonance enhances he sabi ol compis. For example, acetylacetonate anion ligand so
resonance and for stable celtd complex.
Dach at
CH; CH 6 Cy Gt; — € = CH — 0 CH;
Asa resultof resonance the MO tons are equal in lega and sengh
(6) Steric Effect or Steric Hindrance
If à bulky group is either ataced o dor atom or 1 the atom adjacent o don atom,
metabligand bond becomes weak andthe stably of the complex decreases. This effect is called st
effet, For examples
(6) Ethylene diamine (HN CH, —CHa —NH) and N— tetramethyl cisne
(CH) N—CH.—CH,—N(CH)j boar bidentate igands and form cheats with Ni? ion sho
inFigue?a. E
ce ye r oe pe
DES ol,
me | neat Lau
cha, ad AGE
of
a GN a
18 PATES
te De Het ome
no
o an
Te complex (Din es able han) becas in complex (I) the met! groups tache 1 of
Atom cet tri hindeanc nd dern sabi o comple
we
Ses ANN
GDS Hydro quinoline aná 2 met hydroxy quioline both are bidentate igands and form
elated compleses with Ni? ion as shown in Figure 7.5,
m.
o pa
he complex (I ies stable than complex (because in complex (a ul groups tach to
an tom dent ona om wich ases seri indrance and lower he hi fée cop.
The cheats containing cclinglgnds with delocalized lectrices are als stubiized
by econo effet in alton 1 entopy effect. The examples of such pe of igs are imine
ligands suchas bipyridine and ophesanoline. These ligands sblize he compexesbecase of cr
ability to act as o-donors as wellas macceptors. These ligands form sebonds by overlapping heir empty
ing x” orbits wi fil mel dera. An important example of such type Of complexes Is
‘Rutbry), * (eure 76) =,
+ o
7 pe di
2
a
À KINETIC STABILITY : LABILITY AND INERTNESS
Kin silty refs othe mt ofresco which is governed by i tition eu, ete
constant Kinet ably ls to ow at a impound tes ac a how SA à ca he
basi of ie of cc, term ke DIT Ed int bility and nenes
“The complex in vih subio of oor more ligands by snot ces ey ae cle
Intl complex, The bility oa complex o give ubstton nein Ely scale city of
that compe al ue Cll complezs or substation eos es thn one ne
comple o which substation easton og low or ot tall ae cal tomes al
ii of ine comple oval bai cons gar han on il.
“The inability or less ability ofa complex to BE escions wit oder ligands is called
ines he plex
RMODYNAMIC STABILITY. VERSUS KINETIGSTABILTT
he thermodynamic ters (stable and unstable) refers to the tendency ofa complex 1 exist under
equilibrium conditions and the thermndyoamic stability is related tothe change in ro ener, enthalpy
and enropy often. The compound may be unstable with epetio april condition or rage
Such asa igh aid orbs.
“The kinetic stability (lability and inertness) refers to the rate of reaction and mechanisms ofreactions
such as abat and electron tester reactions.
2, Toll e dicos btwcaihermod mamis and ini sb, conser o complexes
TND) MCD a{CHCN) |. Al hee complex ar emodsmanicly sable bt
‘Kinetic stability is different. The rate 6f exchange can be measure when carbon-14 labeled cyanide ions
ae placed in solution withthe complex. I is observeil hat {Ni(CN)]* is abile[Ma(CN)g]* is ess
>
Teile and (CCT isin. pre
pa enr lt ar E
cle
ty =308, L
“cr alte E Ma CNP +607
fy =the
Ay +6 PRE, Ou CN)e 1 +6CN™
= ty =24 days
In contrast, for example [Co(NHy)6]°* complex ion is inert to substation but it is
thermodyzanicalyusuble id soon
ICO)" +6130" CO O EP EN |
Te furmatio cocsant for this reaction is very large (~ 10°). This indicates thatthe complex
[Co(NH Js)" is unstable in acidic solution. On the offer hand, it takes several days at room
‘temperature to form(Co(H¿0)]?* complex Le, the rate of this reaction is slow and hence the complex
[Co(NH3)5]* is kinetically inert,
} The above dicusion indicates thet hero dynamic terms (ble and usable) are ot related to
netic terms (bla nennen).
-
SUBSTITUTION REACTION. IN OCTAHEDRAL COMPLEXES
Substitution rections involve the replacement of one ligand in coordination sphere by another
without an change in coordination number and oxidation state of meal ation. For example, octal
Sn o tor bound 1 re int ans (y ande le andy
X) which st be replaced by an incoming ligand (Y) . The overall reaction is sown bel:
[MLsX]+Y — ML +X
Since ligands behave as mileaphile,theefore, these reactions ae called miceopilic substitution
reactions or ligand substition reactions.
Ses ANN
GDS Hydro quinoline aná 2 met hydroxy quioline both are bidentate igands and form
elated compleses with Ni? ion as shown in Figure 7.5,
m.
o pa
he complex (I ies stable than complex (because in complex (a ul groups tach to
an tom dent ona om wich ases seri indrance and lower he hi fée cop.
The cheats containing cclinglgnds with delocalized lectrices are als stubiized
by econo effet in alton 1 entopy effect. The examples of such pe of igs are imine
ligands suchas bipyridine and ophesanoline. These ligands sblize he compexesbecase of cr
ability to act as o-donors as wellas macceptors. These ligands form sebonds by overlapping heir empty
ing x” orbits wi fil mel dera. An important example of such type Of complexes Is
‘Rutbry), * (eure 76) =,
+ o
7 pe di
2
a
À KINETIC STABILITY : LABILITY AND INERTNESS
Kin silty refs othe mt ofresco which is governed by i tition eu, ete
constant Kinet ably ls to ow at a impound tes ac a how SA à ca he
basi of ie of cc, term ke DIT Ed int bility and nenes
“The complex in vih subio of oor more ligands by snot ces ey ae cle
Intl complex, The bility oa complex o give ubstton nein Ely scale city of
that compe al ue Cll complezs or substation eos es thn one ne
comple o which substation easton og low or ot tall ae cal tomes al
ii of ine comple oval bai cons gar han on il.
“The inability or less ability ofa complex to BE escions wit oder ligands is called
ines he plex
RMODYNAMIC STABILITY. VERSUS KINETIGSTABILTT
he thermodynamic ters (stable and unstable) refers to the tendency ofa complex 1 exist under
equilibrium conditions and the thermndyoamic stability is related tothe change in ro ener, enthalpy
and enropy often. The compound may be unstable with epetio april condition or rage
Such asa igh aid orbs.
“The kinetic stability (lability and inertness) refers to the rate of reaction and mechanisms ofreactions
such as abat and electron tester reactions.
2, Toll e dicos btwcaihermod mamis and ini sb, conser o complexes
TND) MCD a{CHCN) |. Al hee complex ar emodsmanicly sable bt
‘Kinetic stability is different. The rate 6f exchange can be measure when carbon-14 labeled cyanide ions
ae placed in solution withthe complex. I is observeil hat {Ni(CN)]* is abile[Ma(CN)g]* is ess
>
Teile and (CCT isin. pre
pa enr lt ar E
cle
ty =308, L
“cr alte E Ma CNP +607
fy =the
Ay +6 PRE, Ou CN)e 1 +6CN™
= ty =24 days
In contrast, for example [Co(NHy)6]°* complex ion is inert to substation but it is
thermodyzanicalyusuble id soon
ICO)" +6130" CO O EP EN |
Te furmatio cocsant for this reaction is very large (~ 10°). This indicates thatthe complex
[Co(NH Js)" is unstable in acidic solution. On the offer hand, it takes several days at room
‘temperature to form(Co(H¿0)]?* complex Le, the rate of this reaction is slow and hence the complex
[Co(NH3)5]* is kinetically inert,
} The above dicusion indicates thet hero dynamic terms (ble and usable) are ot related to
netic terms (bla nennen).
-
SUBSTITUTION REACTION. IN OCTAHEDRAL COMPLEXES
Substitution rections involve the replacement of one ligand in coordination sphere by another
without an change in coordination number and oxidation state of meal ation. For example, octal
Sn o tor bound 1 re int ans (y ande le andy
X) which st be replaced by an incoming ligand (Y) . The overall reaction is sown bel:
[MLsX]+Y — ML +X
Since ligands behave as mileaphile,theefore, these reactions ae called miceopilic substitution
reactions or ligand substition reactions.
Mechanism in Octahedral Complexes
‘The mechanism of a reaction is the sequence of elementary reactions involved in a reaction.
Subsition reactions in octahedral complexes take place through ether of the following three
mechanism
1. Dissociative (D) Mechanism Sa!
2. Associative (A) Mechanisms,
3. Interotango () Mechanism
1. Dissociative (D) Mechanism : In the dissociative mechanism, there is à sep in which an
intermediate of reduced coordination number is formed te, the M-X bond is fal broken before the
MEY bond begins o form.
O]
Intermedio
ENS
L L
L LI
> M & OR ML
ı/ aa
Seca L
ie op
sre Li anne ligand Xi abi eaving land) and sth ent i
“Teta deeming step sth slowest element ration. Teratof oval station reaction
depends only on the concentration of the original complex, [MLsX] and is independent of the
concerto of te incoming ind Y.
Rate = k(MLSX)
“This reactions of first order in{ML5XJand {ML X] gets dissociate rate determining step. Thus,
‘this reaction is also called dissociative SN! mechanism (substitution, nucleophilic first order).
Mos sition reactions in ocabedral complex takes place by sche mecanis in
hic an intermediate of coordination number 5 (mast prole quar pyrmi) formed
2. Associative (A) Mechanism : An asocio mechanism ins a sep in which an
inemediate is ed with «higher coordination number ante orinal comple. the incoming
ligand Y dirty tacks he original complex 1 form an nt mediate witha coin number Tin
th atdetemining ep The rat determining ste is tow
ir
Erg] sum
Interdite
CNT
This intermediate might be expected a monocapped octahedral structure in which the X and Y
ligands share da of the octahedrl sites oa pentagonal bicamidal sructme. The second step is the
section of igand X to give the product. The rate of rescton depends on the concentration ofboth
MLsX and Y. Therefore,
Rate = KML ION
‘This reaction i of second order and this associative mechanism also called SN? (Substitution,
nucleopiti second oe) mechanism.
3 Iterchunge(Mechantsm: This mechanism takes pe ion sep without forming fly
sable needa, instead the leaving and entering Ligands exchange ia a ingle step forming an
activate. Theinechange mechanism i common fr many reactions focal comple.
The arte complex (aso called as transition tt) has vey lite or no sabilzation energy and
rai pases on to products or ever tothe reactants.
sue À LIM Y LM XT Lex
Activated complex
In is mechanism the M-X bond begins to break and sss to move away fram the metal and the
MY bonds begias to form simultaneously and Y moves into the coordination sphere and no stable
intermediate j formed. Sa
Interchange mechanism is suhdevided into two categories:
(D) Interchange Disociative La)
di) Inerchange Associative.)
(D Interchange Dissociative Mechanism (14): The M-Y bond begins to fom before the M-X
bond is filly beoken but the M-X bond breaks preferentially and the interchange is closer (0 2
<ssciative than to an associative mechaaisi, and no detectable intermediate appears.
{i Interchange Associative Mechanism («) : The M-X bond begins to break before the M-Y
bonds fully formed but the M-Y bond forms preferentially and he interchange is loser to associative
and no detectable inermedite appears.
REACTION PROFILES FOR DISSOCIATIVE, ASSOCIATIVE
A plac free energy versus reaction pathway is called action profile oc energy profile.
nanintecchango mechanisu a reactant absorbs energy and combines withthe incoming ligand and
fora an activated complex of transition state before the Formation of product. The energy difference
‘between the reactants and transition stte is called energy of activation, E. The transition sat ies on
‘The mechanism of a reaction is the sequence of elementary reactions involved in a reaction.
Subsition reactions in octahedral complexes take place through ether of the following three
mechanism
1. Dissociative (D) Mechanism Sa!
2. Associative (A) Mechanisms,
3. Interotango () Mechanism
1. Dissociative (D) Mechanism : In the dissociative mechanism, there is à sep in which an
intermediate of reduced coordination number is formed te, the M-X bond is fal broken before the
MEY bond begins o form.
O]
Intermedio
ENS
L L
L LI
> M & OR ML
ı/ aa
Seca L
ie op
sre Li anne ligand Xi abi eaving land) and sth ent i
“Teta deeming step sth slowest element ration. Teratof oval station reaction
depends only on the concentration of the original complex, [MLsX] and is independent of the
concerto of te incoming ind Y.
Rate = k(MLSX)
“This reactions of first order in{ML5XJand {ML X] gets dissociate rate determining step. Thus,
‘this reaction is also called dissociative SN! mechanism (substitution, nucleophilic first order).
Mos sition reactions in ocabedral complex takes place by sche mecanis in
hic an intermediate of coordination number 5 (mast prole quar pyrmi) formed
2. Associative (A) Mechanism : An asocio mechanism ins a sep in which an
inemediate is ed with «higher coordination number ante orinal comple. the incoming
ligand Y dirty tacks he original complex 1 form an nt mediate witha coin number Tin
th atdetemining ep The rat determining ste is tow
ir
Erg] sum
Interdite
CNT
This intermediate might be expected a monocapped octahedral structure in which the X and Y
ligands share da of the octahedrl sites oa pentagonal bicamidal sructme. The second step is the
section of igand X to give the product. The rate of rescton depends on the concentration ofboth
MLsX and Y. Therefore,
Rate = KML ION
‘This reaction i of second order and this associative mechanism also called SN? (Substitution,
nucleopiti second oe) mechanism.
3 Iterchunge(Mechantsm: This mechanism takes pe ion sep without forming fly
sable needa, instead the leaving and entering Ligands exchange ia a ingle step forming an
activate. Theinechange mechanism i common fr many reactions focal comple.
The arte complex (aso called as transition tt) has vey lite or no sabilzation energy and
rai pases on to products or ever tothe reactants.
sue À LIM Y LM XT Lex
Activated complex
In is mechanism the M-X bond begins to break and sss to move away fram the metal and the
MY bonds begias to form simultaneously and Y moves into the coordination sphere and no stable
intermediate j formed. Sa
Interchange mechanism is suhdevided into two categories:
(D) Interchange Disociative La)
di) Inerchange Associative.)
(D Interchange Dissociative Mechanism (14): The M-Y bond begins to fom before the M-X
bond is filly beoken but the M-X bond breaks preferentially and the interchange is closer (0 2
<ssciative than to an associative mechaaisi, and no detectable intermediate appears.
{i Interchange Associative Mechanism («) : The M-X bond begins to break before the M-Y
bonds fully formed but the M-Y bond forms preferentially and he interchange is loser to associative
and no detectable inermedite appears.
REACTION PROFILES FOR DISSOCIATIVE, ASSOCIATIVE
A plac free energy versus reaction pathway is called action profile oc energy profile.
nanintecchango mechanisu a reactant absorbs energy and combines withthe incoming ligand and
fora an activated complex of transition state before the Formation of product. The energy difference
‘between the reactants and transition stte is called energy of activation, E. The transition sat ies on
| eae
AS tnd Rao Mota TA RON:
‘the top of the reaction profile (like ontop of the hi) and at this point reactant convert into product i
without no hesitation {Figure 7.10) and (0). 4
Ifthe activation energy is high, then he rate determing stp i slow and ifthe energy of activation
is tow, rate determining step is fast.
In dissoiaive (D) or associative (A) mechanism an itemmedite of lower coordination number
5) or higher coordination number (= 7) is formed before the formation of product, Because an !
intermediate is more stable than a transition state, therefor i willie ina valley (or bi) in energy profile
[Figure 2.10) and (8)].The stability or existing time ofan ntemnediat ina valley depends on how high
ie energy walls around te intermediate are:
| ao vx
46 6 |
Ces ur
E max yx N
AS Pecos —
a o
MgexeY Mg exe¥
fig
tx
ancient —
a
de tias eii s,
INTE]
1.00 the Basso Valence Bond Theory: Accro VET anson metal form, to ypesof
úctabedral complexes : (i) outer orbital complexes and (i) inner orbital complexes, In outer orbital
complexes, he osterndabitals ar ivolvedin y a” hybiation adininer orbital corilees he
inner (n-1) de orbitals are involved in d?sp?-tybvidization. Thus, the M-L bonds in outer orbital
compleses is ager, weaker an Higher a energy whereas nr abil complexes the M-L bond is
shorter, sor and lower in exergy. Tus, the tanstion meal oca complexes underpoing à
substation reactions throug soso mechanism would be ile ihe ML bond is weak and
‘woul be ins if ML bond is comparatively ong. Ths, acer to VT, ifthe transition metal
complexes undergoing substitution reactions tough disco mechanism then all outer otal
complexes ar abil ad al inner orbital complexes are ine. >
Del
DoL
Farther it is observed thatthe complexes eier inner ori or outer orbital are labio if they have
‘est own ze ma dos lo yr ial), Tee vag tas 2
point of attack for an incoming ligand. Such complexes undergo substitution through associative
‘mechanism in which an intermediate of higher coordination number (= 7) is formed. On the other hand,
the inert complexes have electron density inthe unhybrdized metal (n - 1) orbitals. Some example of
Inte and inert complexes are shown in Table 7.1:
op acia
Though, there are some exceptions ich can be spe on the bass of CFT. For example
acconlngto VETAS) (HS) and ati complexes aveo ow ying vacant abil an,
therfore these complexes. shouldbe inet But expeinetally iis served hie hese Gompleses are
labio
2. On the Bass of Crystal Feld Theory: Outta complexes undergo substitution reactions
through either dissociative (SN!) or associative (SN) mechanisms. The SN! reactions take place
through the lower energy square pyramid inempedit instead of high energy trigonal bipyramidal
intermediates. On the other hand, the SN? reactions occurs through pentagonal bipyramidal
¿ntermetit (CN = 7), Theresa change CFSE on gin om octahedral o square pyramidal (CN,
5) or pentagonal bipyramidal (CN. = 7) tete. here ss is CFSE (represented by nega
St) then the complex wl einer Higher the los in CFSE, mae vil be inertes ofthe complex. I
theeis po loss in CESE (Le, change in CFSE sr oc paie) he complex willbe abil. The change
in CESE is called as crystal ld aciaionenegy(CFAE) Butts dificult to assign the CFSE of the
intermediate o complex without exact knowlege oft stuctue,Baslo and Pearson have calculated
the vales of CFSE for low spin and high spin squre pyramidal and pentagonal bipyramidal
inemede, These values ae given he ble 72.
AS tnd Rao Mota TA RON:
‘the top of the reaction profile (like ontop of the hi) and at this point reactant convert into product i
without no hesitation {Figure 7.10) and (0). 4
Ifthe activation energy is high, then he rate determing stp i slow and ifthe energy of activation
is tow, rate determining step is fast.
In dissoiaive (D) or associative (A) mechanism an itemmedite of lower coordination number
5) or higher coordination number (= 7) is formed before the formation of product, Because an !
intermediate is more stable than a transition state, therefor i willie ina valley (or bi) in energy profile
[Figure 2.10) and (8)].The stability or existing time ofan ntemnediat ina valley depends on how high
ie energy walls around te intermediate are:
| ao vx
46 6 |
Ces ur
E max yx N
AS Pecos —
a o
MgexeY Mg exe¥
fig
tx
ancient —
a
de tias eii s,
INTE]
1.00 the Basso Valence Bond Theory: Accro VET anson metal form, to ypesof
úctabedral complexes : (i) outer orbital complexes and (i) inner orbital complexes, In outer orbital
complexes, he osterndabitals ar ivolvedin y a” hybiation adininer orbital corilees he
inner (n-1) de orbitals are involved in d?sp?-tybvidization. Thus, the M-L bonds in outer orbital
compleses is ager, weaker an Higher a energy whereas nr abil complexes the M-L bond is
shorter, sor and lower in exergy. Tus, the tanstion meal oca complexes underpoing à
substation reactions throug soso mechanism would be ile ihe ML bond is weak and
‘woul be ins if ML bond is comparatively ong. Ths, acer to VT, ifthe transition metal
complexes undergoing substitution reactions tough disco mechanism then all outer otal
complexes ar abil ad al inner orbital complexes are ine. >
Del
DoL
Farther it is observed thatthe complexes eier inner ori or outer orbital are labio if they have
‘est own ze ma dos lo yr ial), Tee vag tas 2
point of attack for an incoming ligand. Such complexes undergo substitution through associative
‘mechanism in which an intermediate of higher coordination number (= 7) is formed. On the other hand,
the inert complexes have electron density inthe unhybrdized metal (n - 1) orbitals. Some example of
Inte and inert complexes are shown in Table 7.1:
op acia
Though, there are some exceptions ich can be spe on the bass of CFT. For example
acconlngto VETAS) (HS) and ati complexes aveo ow ying vacant abil an,
therfore these complexes. shouldbe inet But expeinetally iis served hie hese Gompleses are
labio
2. On the Bass of Crystal Feld Theory: Outta complexes undergo substitution reactions
through either dissociative (SN!) or associative (SN) mechanisms. The SN! reactions take place
through the lower energy square pyramid inempedit instead of high energy trigonal bipyramidal
intermediates. On the other hand, the SN? reactions occurs through pentagonal bipyramidal
¿ntermetit (CN = 7), Theresa change CFSE on gin om octahedral o square pyramidal (CN,
5) or pentagonal bipyramidal (CN. = 7) tete. here ss is CFSE (represented by nega
St) then the complex wl einer Higher the los in CFSE, mae vil be inertes ofthe complex. I
theeis po loss in CESE (Le, change in CFSE sr oc paie) he complex willbe abil. The change
in CESE is called as crystal ld aciaionenegy(CFAE) Butts dificult to assign the CFSE of the
intermediate o complex without exact knowlege oft stuctue,Baslo and Pearson have calculated
the vales of CFSE for low spin and high spin squre pyramidal and pentagonal bipyramidal
inemede, These values ae given he ble 72.
a o o o o
a +057 +12 +057
By e en +256 eu
¡SA -20 -426 200
> e +38 -107 163
Q a o o -086
à a +057 +128 400
a +11 +256 Ben
a -200 4% 200
# 431 -107 rs
ae o o o o
‘SUSU ini PALIAR CEN ire an
Since the substitution resctions in most of the octal complexes proceed though square
pyramidal intemnedite (C.N.= 5e, dissociative mechanism, comparision of inemers or ability
‘made onthe basis of change in CFS from actabedral complex to square pyrmidlitemediat.
“The onder of ability of complexes of tripstiv metal ations of series is z
Co) < Cr) <Ma (D) < Fe ll) <TEAM) <V (UD)
EC. 4 D dd à we
Less in CFSE, ¿00 200 “143 086 +057 F.1d
RESN! mectadism. = : —
For isoelectronic mea cons, the lily of complex decreases wit increase i charge on metal
ation because high charge strengthen the M-L bond and reduces the lability. For example,Cr**(4*)
complexes are more inert than V7" (d° ) complexes. Similarly Fe** (45) complexes are more inert than
analogous complexes of Ma”)
It is observed that inertes of analogous complexes of sole metal cation increases on
descending within the group because (D 44-and Serie metal eations aro large then the series
mci te sae gv ee tics an he igs ound thee san,
there sten fra gio mre eat rin pee. i) Aan ei
metal cations ae larger and we 4 he ormation of sigma bonds with igands. Since
48. and Schorbital ar diffuse, lage) 0 these obits extend toward ligands and vera with
‘igands orbitals more effectively and thus asrong M-L bond is formed and itis ficult 1 breakin the
te deermining step of dissociative reaction
agi EEN
Exceso ga omega lis: 38
CoQ)<RR (MD <QID (Grupo) WS
Ni) <P40 <P. (Group 10)
fis tobe noted that Cx? (@?) and Cr) ae complexes have #2 changes ander is
lesan gang CFSE O gn fo ocd tinted. Tess comple have aes ater
‘xchange because Wr Wälermerules above and below he square plane se fa apar fom the Cu" oa
compared 10 ote four water molcale, There, hese two water molecules above and blow the
square plane react rapidly
Other Factors Affecting the Lability of a Complex
(0) Geometry ofthe Complex; The complexes of CN. 4 undergo substitution reactions more
rapidl than analogous compounds of CNS, For example, {Ni(CN) 4)?" give exchange reaction with
MCN more rapidly than {Mn (CN) and [Co(CN)g]> complexes. The greater lability of square
plana compen (NEC) a] is due tothe ran tht tere is enough room ound he ml eon or
the entry of incoming ligand it coordination pee to form activated complex. This it igand
tances the at of removal of one ofthe our gan already present in the coordination spe
“Q) Oxidation State of Central Meat Cain: Higher ih oxidation state of cena meal eatin,
lower wil he lbility of the comple
For example:
A en CE
GARD > BR > (BEST > LS Fo)
se A E
aero SS > O
(©) Tonic Radius: Labily of complex increases wit incre in ionic reds, Por exampe
HO > {CX 0)6}* > (Mat: 0)
EVIDENCE FOR DISSOCIATIVE (SN) MECHANISM
“The most prefered mechanisn foc substnsion reactions in actahedral complexes is dissociative
mechanism However associative eectons ae also possible in otabedral substituionbutare much ess
common. Some evidence which support the dissociative mechanism are
(the rate of exchange of water molecules
(2) anation reactions. ‘
(9 aquation or hydrolysis reactions
ñ E
E ad
Jos arab e © MOO“ Os
(1) Water Exchange
‘When water molecules in th coordicaion sphere are exchanged with isotopically labeled bulk
water (4800), the process i called water exchange.
EMO) HO" MELO) AO!) +120
a +057 +12 +057
By e en +256 eu
¡SA -20 -426 200
> e +38 -107 163
Q a o o -086
à a +057 +128 400
a +11 +256 Ben
a -200 4% 200
# 431 -107 rs
ae o o o o
‘SUSU ini PALIAR CEN ire an
Since the substitution resctions in most of the octal complexes proceed though square
pyramidal intemnedite (C.N.= 5e, dissociative mechanism, comparision of inemers or ability
‘made onthe basis of change in CFS from actabedral complex to square pyrmidlitemediat.
“The onder of ability of complexes of tripstiv metal ations of series is z
Co) < Cr) <Ma (D) < Fe ll) <TEAM) <V (UD)
EC. 4 D dd à we
Less in CFSE, ¿00 200 “143 086 +057 F.1d
RESN! mectadism. = : —
For isoelectronic mea cons, the lily of complex decreases wit increase i charge on metal
ation because high charge strengthen the M-L bond and reduces the lability. For example,Cr**(4*)
complexes are more inert than V7" (d° ) complexes. Similarly Fe** (45) complexes are more inert than
analogous complexes of Ma”)
It is observed that inertes of analogous complexes of sole metal cation increases on
descending within the group because (D 44-and Serie metal eations aro large then the series
mci te sae gv ee tics an he igs ound thee san,
there sten fra gio mre eat rin pee. i) Aan ei
metal cations ae larger and we 4 he ormation of sigma bonds with igands. Since
48. and Schorbital ar diffuse, lage) 0 these obits extend toward ligands and vera with
‘igands orbitals more effectively and thus asrong M-L bond is formed and itis ficult 1 breakin the
te deermining step of dissociative reaction
agi EEN
Exceso ga omega lis: 38
CoQ)<RR (MD <QID (Grupo) WS
Ni) <P40 <P. (Group 10)
fis tobe noted that Cx? (@?) and Cr) ae complexes have #2 changes ander is
lesan gang CFSE O gn fo ocd tinted. Tess comple have aes ater
‘xchange because Wr Wälermerules above and below he square plane se fa apar fom the Cu" oa
compared 10 ote four water molcale, There, hese two water molecules above and blow the
square plane react rapidly
Other Factors Affecting the Lability of a Complex
(0) Geometry ofthe Complex; The complexes of CN. 4 undergo substitution reactions more
rapidl than analogous compounds of CNS, For example, {Ni(CN) 4)?" give exchange reaction with
MCN more rapidly than {Mn (CN) and [Co(CN)g]> complexes. The greater lability of square
plana compen (NEC) a] is due tothe ran tht tere is enough room ound he ml eon or
the entry of incoming ligand it coordination pee to form activated complex. This it igand
tances the at of removal of one ofthe our gan already present in the coordination spe
“Q) Oxidation State of Central Meat Cain: Higher ih oxidation state of cena meal eatin,
lower wil he lbility of the comple
For example:
A en CE
GARD > BR > (BEST > LS Fo)
se A E
aero SS > O
(©) Tonic Radius: Labily of complex increases wit incre in ionic reds, Por exampe
HO > {CX 0)6}* > (Mat: 0)
EVIDENCE FOR DISSOCIATIVE (SN) MECHANISM
“The most prefered mechanisn foc substnsion reactions in actahedral complexes is dissociative
mechanism However associative eectons ae also possible in otabedral substituionbutare much ess
common. Some evidence which support the dissociative mechanism are
(the rate of exchange of water molecules
(2) anation reactions. ‘
(9 aquation or hydrolysis reactions
ñ E
E ad
Jos arab e © MOO“ Os
(1) Water Exchange
‘When water molecules in th coordicaion sphere are exchanged with isotopically labeled bulk
water (4800), the process i called water exchange.
EMO) HO" MELO) AO!) +120
‘Tae rate of water exchange depends onthe ratio of charge on metal cation tits ionic radius, This
ratio charge one radius cal density. The charge density of metal cations increases with
increasing charge and decreasing joni radius. As the charge density increases, M OH} bond sength
increases because high charge density (Le, high charge and small size) causes rester electosaic
traction between metal cation and the water molecules, Within given group allthecations have same
charge but the size increases on descending the group. Thus, on moving down le group, te size
inereases and charge density decreases aud the M—OH bond becomes larger and weaker and brats
more easly. The breaking of M—OH, bond isthe rate-determining step in dissociative mechanism Ze,
SN! mechanism, Thus, these reactions ar of fist order.
‘Meta fons ae classified into four categories based on the rate of exchange of coordinated water
Class à The rate of exchange of wales is very fast. Rate constants fo water exchange are ofthe
ander of 10°5" These reactions are difusion controlled reactions. Tons tat include in this class are
alkali metals, alkaline earth metas (except Be?" and Mg”), group 12 elements (except Zn"), Cr2*
and Cu from first transition series,
Class IL: The rate of exchange of water is fast but slower than that of class I metals. The rate
constats for water exchange ae in he range of 10° to 0° 5-1, The metal insta include in this class
positive transition metal from first transition series (except V2* which is slower and Cr?" and
Cu wich ae in las 1), Mg?" and TH and the trivalent lanthanoids
(Class HH : Rate of water exchange is comparatively smaller than that of cas and I metal ons.
‘The rate constanis for waterexchange are 11010" s"!. This class includes most of the vale transition
‘metal ions of frst transition series, Be™*, V?*, A1%* and Ga>* ions.
(Class IV : The rate ofexchange Of wate is very small and these ae inet hydrtedcomplexes. The
rate constants for water exchange are 10 to 10251. This dass includes
Cr Co, Rh, Ru, Ru, 17 and PL on.
se
The rate of water exchange in hexaaqua ions follow the order pa
Vien che cpl za ce gu
and CP cv ck eT TA
ye
(2) Anation Reactions” 7" ~ RS
Jn thes easton an aion places an ag (4,0) gend fom cordon sphere ofa ya
compe,
LEO)" +X” — (M(H20)s XI" 4 130
Such ype of reasons may proces by ether dissociative or associative medians bt most
evidence favour the dissociative mechanism. The classic examples in the suppor of dissociative
mechanism sre
NO)" +X7—> [Ni(4120)5X]" + HO.
Where X =F SON” and CH,000".
‘The rate constant of these reactions (8 x.10° 5, 6 x 10°
determining step is Ni?* — OH, bond breaking.
nd 30 x 10° 5) suggest, hat the rate
REG EEE
An another example o dsacative mechanism i :
(Ni(Hz0)6]?* +NH3— [NI(H2O)s (NH) +30
For hi reaction, the rate dctemining step is Ni”* — OH bond breaking and he at constant for
rate determining step is 4 x 10° $,
(8) Aquation or Hydrolysis Reactions
The substitution reactions in which a ligand is replaced by water molecule ar called aquation
reactions or hydrolsisreacions. Te aquation reactions may be carried it either in acidic or neural or
basic medium.
Ifthe hydrolysis is cared ontin acidic medium, then itis called acid hydrolysis andi this reaction a
ligand is replaced by HzO molecule. Ifthe hydrolysis is carried out in bac medium (HE > 8) the tis
called base hydrolysis and in his reaction a ligand i replaced by OH” group.
‘At intermediate value of pl the reaction is simply called as hydrolysis aad both path willbe
available
For example, qution ofthe ligand X” in ammine complexes of Co (I) in aide (pH <3) and
basic (pH > 8) medium is shown below:
‘AC pH<3: EL o
(Go (NE )gXP* +20 — (CON }s H2OM* +%” (Acid ydrolsis)
were X" = FC" BrP NCS" NOs je bal
AUS
[Co(NH3)5CI]?!+0H" —> [Co(NH3)s(OH)]?* +CI" (Base hydrolysis)
: eo Law, 0
(0 Acid Hydrolysis of Cobalt (i) Ammine Complexes
Amine compless of cabal UI) have been most widely sie. In acid his, water
molecule replace a ligand (say X”) from the coordination sphere. Since eatrng ligand (H20) is
present in consta concentra, he rat law, therefore, does not contain (0). Th, itimpis ha,
the hydrolysis reactions are of ft ode. pote
/ Rae CN) XP Rat HY bo
where isthe ate ont for aci hydrolyis. ,
This rat law does no indice whether these seacions proceed by SN or SN? mechanisms
‘However, ias been observed that mos cd bydolyss reactions of octahedral complers proceed by
ar ee le th pr e iso metas radios)
ammine complexes.
Eco ening Group: The bond eng of mega’ bod pis ame rl
ring th Gina oft ving ligand, Aste retain band senil
Sica renover admet lbs ecc eras Tentation
‘related to the rate constant (+, )and the smallest value of k, have the slowest rate of reaction and the
ML bond ste mi to eur constant (A), Large vale of quicio cost (4)
ratio charge one radius cal density. The charge density of metal cations increases with
increasing charge and decreasing joni radius. As the charge density increases, M OH} bond sength
increases because high charge density (Le, high charge and small size) causes rester electosaic
traction between metal cation and the water molecules, Within given group allthecations have same
charge but the size increases on descending the group. Thus, on moving down le group, te size
inereases and charge density decreases aud the M—OH bond becomes larger and weaker and brats
more easly. The breaking of M—OH, bond isthe rate-determining step in dissociative mechanism Ze,
SN! mechanism, Thus, these reactions ar of fist order.
‘Meta fons ae classified into four categories based on the rate of exchange of coordinated water
Class à The rate of exchange of wales is very fast. Rate constants fo water exchange are ofthe
ander of 10°5" These reactions are difusion controlled reactions. Tons tat include in this class are
alkali metals, alkaline earth metas (except Be?" and Mg”), group 12 elements (except Zn"), Cr2*
and Cu from first transition series,
Class IL: The rate of exchange of water is fast but slower than that of class I metals. The rate
constats for water exchange ae in he range of 10° to 0° 5-1, The metal insta include in this class
positive transition metal from first transition series (except V2* which is slower and Cr?" and
Cu wich ae in las 1), Mg?" and TH and the trivalent lanthanoids
(Class HH : Rate of water exchange is comparatively smaller than that of cas and I metal ons.
‘The rate constanis for waterexchange are 11010" s"!. This class includes most of the vale transition
‘metal ions of frst transition series, Be™*, V?*, A1%* and Ga>* ions.
(Class IV : The rate ofexchange Of wate is very small and these ae inet hydrtedcomplexes. The
rate constants for water exchange are 10 to 10251. This dass includes
Cr Co, Rh, Ru, Ru, 17 and PL on.
se
The rate of water exchange in hexaaqua ions follow the order pa
Vien che cpl za ce gu
and CP cv ck eT TA
ye
(2) Anation Reactions” 7" ~ RS
Jn thes easton an aion places an ag (4,0) gend fom cordon sphere ofa ya
compe,
LEO)" +X” — (M(H20)s XI" 4 130
Such ype of reasons may proces by ether dissociative or associative medians bt most
evidence favour the dissociative mechanism. The classic examples in the suppor of dissociative
mechanism sre
NO)" +X7—> [Ni(4120)5X]" + HO.
Where X =F SON” and CH,000".
‘The rate constant of these reactions (8 x.10° 5, 6 x 10°
determining step is Ni?* — OH, bond breaking.
nd 30 x 10° 5) suggest, hat the rate
REG EEE
An another example o dsacative mechanism i :
(Ni(Hz0)6]?* +NH3— [NI(H2O)s (NH) +30
For hi reaction, the rate dctemining step is Ni”* — OH bond breaking and he at constant for
rate determining step is 4 x 10° $,
(8) Aquation or Hydrolysis Reactions
The substitution reactions in which a ligand is replaced by water molecule ar called aquation
reactions or hydrolsisreacions. Te aquation reactions may be carried it either in acidic or neural or
basic medium.
Ifthe hydrolysis is cared ontin acidic medium, then itis called acid hydrolysis andi this reaction a
ligand is replaced by HzO molecule. Ifthe hydrolysis is carried out in bac medium (HE > 8) the tis
called base hydrolysis and in his reaction a ligand i replaced by OH” group.
‘At intermediate value of pl the reaction is simply called as hydrolysis aad both path willbe
available
For example, qution ofthe ligand X” in ammine complexes of Co (I) in aide (pH <3) and
basic (pH > 8) medium is shown below:
‘AC pH<3: EL o
(Go (NE )gXP* +20 — (CON }s H2OM* +%” (Acid ydrolsis)
were X" = FC" BrP NCS" NOs je bal
AUS
[Co(NH3)5CI]?!+0H" —> [Co(NH3)s(OH)]?* +CI" (Base hydrolysis)
: eo Law, 0
(0 Acid Hydrolysis of Cobalt (i) Ammine Complexes
Amine compless of cabal UI) have been most widely sie. In acid his, water
molecule replace a ligand (say X”) from the coordination sphere. Since eatrng ligand (H20) is
present in consta concentra, he rat law, therefore, does not contain (0). Th, itimpis ha,
the hydrolysis reactions are of ft ode. pote
/ Rae CN) XP Rat HY bo
where isthe ate ont for aci hydrolyis. ,
This rat law does no indice whether these seacions proceed by SN or SN? mechanisms
‘However, ias been observed that mos cd bydolyss reactions of octahedral complers proceed by
ar ee le th pr e iso metas radios)
ammine complexes.
Eco ening Group: The bond eng of mega’ bod pis ame rl
ring th Gina oft ving ligand, Aste retain band senil
Sica renover admet lbs ecc eras Tentation
‘related to the rate constant (+, )and the smallest value of k, have the slowest rate of reaction and the
ML bond ste mi to eur constant (A), Large vale of quicio cost (4)
«pic hat he igandistightty bound to metal and conespondingto large value of equlibium constant
ML bonddisociation sea nd the value, is male, rt ofrecio low. Thus, its een
thatthe rte constant sine elated othe equilibrium constant
Mathematically,
Be: TIAS
Inky «na E med.
(inc pas era ea)
fpr exponential ator and entopy AS are constant are the energy ofacvaion, E depends on
coa of action, AA hen in and I Kar related lina.
Ta graph is ploted between Ink, and Ink for various (Co(NHs)sX}* cations (where
X=NO5,1 ,Br’,C1”,P” ec), a straight ine I obtained Figue 7.
Leaky
ao 12 3 6
Log —
From the Figure 78 has been observed atthe reactivity o X” groups decreases inthe order
NOS 51° > Br” Cr > > NCS
‘The ig 73 shows tha the stronger the M-L bord, lower is ete of aqua.
is experimentally observed that most ofthe acid hyéolyss runs pies by dsociatve
IN) mechanism.
Ai) Charge let: ‘The higher postive charge on comple ction mikes bond breaking betwen
alana iad moro dificult and, therefore, rate fiction vit lower, Fr ample, aquation
CON; ICI is tower than tha of es CON Cla}
Ene lol provide tabu
o
less Count
N GR
{Co(QHis)sCI}** + HO CORE )s ROM" 5”; hy 67 X10*S
trans (CANES Cle + HO — [CONT ALOE?" 4 hs = 18 10 €
Ai increase i le constant as charge dereaes on complex con fl bas been acoepted as
dene a discale mechanism. —
(ip) Eee of Chelation : Let us consider the aqu of the nan<helated complex,
{Co(NHs }sC1}** and a chelated complex, [Cofen)>(NH3 JC1?" by dissociative mechanism.
(Co) CAP 55 (Co); + CT
at
CON) +120 FE TC
ken N JON FE Cafe) tt #7
as
ta
Cole), HI" + HO (Cafe
vs sen tha the intermediate obtained from tne chelated comple is larger in sie thas that ofthe
itemedi chained hom oor-chelated complex. Theres ess ration between larger intermediate
nd wate mlealesthan between smaller intennedate and water molecules. Ths, chelated complex
idee aqu a shower rate than non-chelated comple In a similar vaa lager chelated
‘complex undergoes uation at slower ae than hat of smal chelted comple,
(1) Serie Hindrane EH on) ether of carbon or togen atoms of en" group of trans
{Co(en)Clp]* are replaced by the alkyl groups like CH CH; ete the ligand becomes more bulky. It
is observed that mace isthe strc hindrenc (Le, crowding, be faster isthe at of equation. Now the
sion that he anton i conse! with cier a dissociate or socie mechanisn.
‘the aquation takes place by associative mechanism, due to serie hindrance is difficult to reach
the water mola o the metal cation to form seven coors intermediate and, therefore, the
socie mecbaniam snot posible.
Out ote hand, ifthe strained complex undergoes aqua ection by dissuciative mechanism,
the sti idrence ound the etl ation forces the chlor gard out ofthe coidnation sphere and
ilot of ie corinne is formed, Since five coral intermedia ses strained than the
Signal comple, there, the aquaton proceeds by disoiatve mechanism. Ths, an increase in
Stet indene favour a dissociative mechanism.
Base Hydrolysis
Replace of a lgand rom coordination sphere by OH” is call base hydrolysis. The most
suitable mechanism bas been given by Gartick which iscalledasSN'CB(sbsttaion aucleophili, st
cres conjgat base) mechan
“The medhinism of Col) complexes containing amine ind is shown below
as,
TEE) C1?* + OH ICONE; a NAIC +70 ©
LCR DA (NH IOU $F IC) QM" + ai)
ML bonddisociation sea nd the value, is male, rt ofrecio low. Thus, its een
thatthe rte constant sine elated othe equilibrium constant
Mathematically,
Be: TIAS
Inky «na E med.
(inc pas era ea)
fpr exponential ator and entopy AS are constant are the energy ofacvaion, E depends on
coa of action, AA hen in and I Kar related lina.
Ta graph is ploted between Ink, and Ink for various (Co(NHs)sX}* cations (where
X=NO5,1 ,Br’,C1”,P” ec), a straight ine I obtained Figue 7.
Leaky
ao 12 3 6
Log —
From the Figure 78 has been observed atthe reactivity o X” groups decreases inthe order
NOS 51° > Br” Cr > > NCS
‘The ig 73 shows tha the stronger the M-L bord, lower is ete of aqua.
is experimentally observed that most ofthe acid hyéolyss runs pies by dsociatve
IN) mechanism.
Ai) Charge let: ‘The higher postive charge on comple ction mikes bond breaking betwen
alana iad moro dificult and, therefore, rate fiction vit lower, Fr ample, aquation
CON; ICI is tower than tha of es CON Cla}
Ene lol provide tabu
o
less Count
N GR
{Co(QHis)sCI}** + HO CORE )s ROM" 5”; hy 67 X10*S
trans (CANES Cle + HO — [CONT ALOE?" 4 hs = 18 10 €
Ai increase i le constant as charge dereaes on complex con fl bas been acoepted as
dene a discale mechanism. —
(ip) Eee of Chelation : Let us consider the aqu of the nan<helated complex,
{Co(NHs }sC1}** and a chelated complex, [Cofen)>(NH3 JC1?" by dissociative mechanism.
(Co) CAP 55 (Co); + CT
at
CON) +120 FE TC
ken N JON FE Cafe) tt #7
as
ta
Cole), HI" + HO (Cafe
vs sen tha the intermediate obtained from tne chelated comple is larger in sie thas that ofthe
itemedi chained hom oor-chelated complex. Theres ess ration between larger intermediate
nd wate mlealesthan between smaller intennedate and water molecules. Ths, chelated complex
idee aqu a shower rate than non-chelated comple In a similar vaa lager chelated
‘complex undergoes uation at slower ae than hat of smal chelted comple,
(1) Serie Hindrane EH on) ether of carbon or togen atoms of en" group of trans
{Co(en)Clp]* are replaced by the alkyl groups like CH CH; ete the ligand becomes more bulky. It
is observed that mace isthe strc hindrenc (Le, crowding, be faster isthe at of equation. Now the
sion that he anton i conse! with cier a dissociate or socie mechanisn.
‘the aquation takes place by associative mechanism, due to serie hindrance is difficult to reach
the water mola o the metal cation to form seven coors intermediate and, therefore, the
socie mecbaniam snot posible.
Out ote hand, ifthe strained complex undergoes aqua ection by dissuciative mechanism,
the sti idrence ound the etl ation forces the chlor gard out ofthe coidnation sphere and
ilot of ie corinne is formed, Since five coral intermedia ses strained than the
Signal comple, there, the aquaton proceeds by disoiatve mechanism. Ths, an increase in
Stet indene favour a dissociative mechanism.
Base Hydrolysis
Replace of a lgand rom coordination sphere by OH” is call base hydrolysis. The most
suitable mechanism bas been given by Gartick which iscalledasSN'CB(sbsttaion aucleophili, st
cres conjgat base) mechan
“The medhinism of Col) complexes containing amine ind is shown below
as,
TEE) C1?* + OH ICONE; a NAIC +70 ©
LCR DA (NH IOU $F IC) QM" + ai)
LE Coria €
CSS an Recta MARA AO NES
ICONE U" +10 ES, (Coti) OB)" i)
‘The fist step involves the removal of proton fom NI group by OH” in a rapid acid hase
equilibra forming amide complexion of lover cage a cogat base original amin complex)
‘Then this conjugate base dissociates to loss C1” inslow step [reaction (i)} and finally it for the hydroxo
complex rapidly [reaction (i). Thus, the second step isthe rte determining step. a
re (CHI) complexes containing amine ligands, the rate of base hydrolysis
acid hydrolysis because:
ky > ke
whee is base hydrolysis rate constant ard is acid hydrolysis rate constant.
Gi) Thegnido complex (Le, conjugate bss) has ler carge than its original complex. Ths,
his changeefeerenumes tig removal fbi gd (Le, CI"),
{Gi In amido complex (.e, conjugte base the NH ligand hs the tendency to for: bond by
onaig its lone par of electrons tothe metal non, Co (UI as shown nthe Figure 79.
HAVA 1 ww
DETACETT ETES A
BNC er. +
a? 7 PNT pe
Es Pe
‘The formatio’ of Co-“N bond increases he electron density on cabalt which intur rep
the bile ligand, CI” and the bond alo stabiles the five cordial intermediate. The donor
bonding is a strong evidence of an SN! mechanism. Since the dissociation step which is the rte
Cris ‚step uses the Conjugate base ‘of the original complex, therefore, it is called as SNICB
Te has been suggested tha, the yodo on abstract proton fon he NE, group whichis trons
the leaving group, ¿e., the halo group. ” FEAR
lion times faster
Meee eV
HN) a
D) >
Ha D
bad
Ny RL
Now from acid base equilibrium (i),
mL
LCONH3)sCU OH]
ee isthe equilibrium constant fo acid base eulibiam (),
= K Cots) CON]
i TÔT
Now for cate detemiing step D,
Rat = (CB)
AKICo(Nis ISC" OH}
10)
Rate = ke [Co(NEt3 )sC1**YOH™ }
he is the ate constant for disse of caga as in ate determing sep nd
x
(oi
"he at detemining step is sociation of conjugate base reaction i) bu since its concentration
dependsonthc OH” ion concentration trough cqitom andthe section ae is proportional OH”
ioneancentation,
Base hydrolysis proceeds by SN! mechanism but itis consistent with second order : First order with
respect othe complex and fst order wih respect othe base.
‘Only OH” ions affect the rate of hydolyss and be olher bases are uneffectve as suck. The
acid base equilibrium [reaction ()] is established more rapidly than the over al reaction.
ln base hydrolysis of Co (IT) complexes containing mine ligands, the ive coordinate intermediate
say be ether square pyramidal rigen bipyranidal Fa square planar intermediate is formed, thea
theres no movement of ligands afer removal FCI from he conjugate base. Therefore, under normal
conditions (ce inthe absence of donar gad) the square pyramidal intermediate i more stable than
‘TBP intermediae
(nth other hand, i rigen bipyramidal intermediate there is movement of some ligands which
requires some amount of energy. This, under normal contin Le, in he absence of rhonding) TBP
inédit ses stable. But nthe mido complex of Co), in conjugate base) the ligands sich
as-NH> or RNH™ are coordinated to Co (IH) and these ligands are z-donor. These #-donor ligands form
æbonds with Co (III) ion and the TBP intermediate becomes more stable than the square pyramidal
intermediate because some energy is released in bonding which is greater than the energy required to
form TBP intermediate. Thus, base hyérobis of Co (I) complexes containing amine ligands is
‘expected to proceed by SN (CB mechanism through TBP intermediate.
Forts hydroysis is essential tha there should beat east one ligand in a comple which have
acide protons. The reaction proceeds by N CBrecharistn involving a TBP intermediate. Water, rather
tan OH" is the enering group.
Rae =
by
CSS an Recta MARA AO NES
ICONE U" +10 ES, (Coti) OB)" i)
‘The fist step involves the removal of proton fom NI group by OH” in a rapid acid hase
equilibra forming amide complexion of lover cage a cogat base original amin complex)
‘Then this conjugate base dissociates to loss C1” inslow step [reaction (i)} and finally it for the hydroxo
complex rapidly [reaction (i). Thus, the second step isthe rte determining step. a
re (CHI) complexes containing amine ligands, the rate of base hydrolysis
acid hydrolysis because:
ky > ke
whee is base hydrolysis rate constant ard is acid hydrolysis rate constant.
Gi) Thegnido complex (Le, conjugate bss) has ler carge than its original complex. Ths,
his changeefeerenumes tig removal fbi gd (Le, CI"),
{Gi In amido complex (.e, conjugte base the NH ligand hs the tendency to for: bond by
onaig its lone par of electrons tothe metal non, Co (UI as shown nthe Figure 79.
HAVA 1 ww
DETACETT ETES A
BNC er. +
a? 7 PNT pe
Es Pe
‘The formatio’ of Co-“N bond increases he electron density on cabalt which intur rep
the bile ligand, CI” and the bond alo stabiles the five cordial intermediate. The donor
bonding is a strong evidence of an SN! mechanism. Since the dissociation step which is the rte
Cris ‚step uses the Conjugate base ‘of the original complex, therefore, it is called as SNICB
Te has been suggested tha, the yodo on abstract proton fon he NE, group whichis trons
the leaving group, ¿e., the halo group. ” FEAR
lion times faster
Meee eV
HN) a
D) >
Ha D
bad
Ny RL
Now from acid base equilibrium (i),
mL
LCONH3)sCU OH]
ee isthe equilibrium constant fo acid base eulibiam (),
= K Cots) CON]
i TÔT
Now for cate detemiing step D,
Rat = (CB)
AKICo(Nis ISC" OH}
10)
Rate = ke [Co(NEt3 )sC1**YOH™ }
he is the ate constant for disse of caga as in ate determing sep nd
x
(oi
"he at detemining step is sociation of conjugate base reaction i) bu since its concentration
dependsonthc OH” ion concentration trough cqitom andthe section ae is proportional OH”
ioneancentation,
Base hydrolysis proceeds by SN! mechanism but itis consistent with second order : First order with
respect othe complex and fst order wih respect othe base.
‘Only OH” ions affect the rate of hydolyss and be olher bases are uneffectve as suck. The
acid base equilibrium [reaction ()] is established more rapidly than the over al reaction.
ln base hydrolysis of Co (IT) complexes containing mine ligands, the ive coordinate intermediate
say be ether square pyramidal rigen bipyranidal Fa square planar intermediate is formed, thea
theres no movement of ligands afer removal FCI from he conjugate base. Therefore, under normal
conditions (ce inthe absence of donar gad) the square pyramidal intermediate i more stable than
‘TBP intermediae
(nth other hand, i rigen bipyramidal intermediate there is movement of some ligands which
requires some amount of energy. This, under normal contin Le, in he absence of rhonding) TBP
inédit ses stable. But nthe mido complex of Co), in conjugate base) the ligands sich
as-NH> or RNH™ are coordinated to Co (IH) and these ligands are z-donor. These #-donor ligands form
æbonds with Co (III) ion and the TBP intermediate becomes more stable than the square pyramidal
intermediate because some energy is released in bonding which is greater than the energy required to
form TBP intermediate. Thus, base hyérobis of Co (I) complexes containing amine ligands is
‘expected to proceed by SN (CB mechanism through TBP intermediate.
Forts hydroysis is essential tha there should beat east one ligand in a comple which have
acide protons. The reaction proceeds by N CBrecharistn involving a TBP intermediate. Water, rather
tan OH" is the enering group.
Rae =
by
TLE NRE HR
SARA ae eT
Chelation and the steric hindrance increase the ae of base hydrolysis. The ate of base hydrolysis
high for diamines. I suggests hat reaction proceeds by dissociative mechanism.
Now let us consider rater of bes dl of [Cena LCI” complex ins wbereL = 1,
OH-,NOZ,CN et. E
QA rate of base Ilya of Ce) 20h 11s ste whereas the ae of tne Iosis al
“{Coler)s(802}C1)* aid TOHDCNO is slower than expected. The low ravi of
{Coen (NO2 )CN}* and [Co(en)2 (CNYCI]” complexes to base hydrolysis inspite of relatively larger
value of, cn be explana nto bass of bonding eet which shown blow
mimo
G
“The electron charge tha he amid group provides tothe cobalt atom i removed by sito group
du to M -> N bonding, Ths trucs the tendency of fable group to disociat. The ligand CN”
‘behaves similar o NOS buttoa lesser eat The lie ions do not undergo such bonding and ns
ase easily activated
(9 The rate of hydrolysis of [Co(py)4Cl]* or[CofCN)5CII”" is independent of OH concentration
‘because there is not protonic hydrogen in the two complexes.
@, Let us consider the base hydrolysis of the [Co(tren)(NH3 JCI]?* complex ion. The rate of base
‘hydrolysis depends upon deprotonation of the amino group trans to the leaving group. In other words,
{we can say that the proton of the amino group tráñs lo the leaving group play an important role in the rate.
‘of base hydrolysis. The (Coen}QNH JJ” ion exists in two isomeric forms having the red and the
purple colour. need iome, he Jing group istrans tothe — NE group Fi 7.40) ania
the purple isomer he leaving roup (ete halo group) i rans to the amino group which have no
proton Fig. 71005).
i a
hr Y
EN ENT
ANA TANT
LL ©
Fin: 7.19ated Rad some Mh Paule isomer.
‘The red isomer ofCoften}(NHs JC] ion is hydrolyzed much more faster than the purple isomer,
“The red isomer has a removable Pan onthe nitrogen atom ans to the leaving group. The
deprtanation of amino group by OF ion ads othe formation of igonal hipyrania intermedia
inthe dissociative (D) or interchange diciativ (1) mechanism. The ligand ten stabilizes the TB
intermediate by ligand's amido group to metal interaction between the NH” group lone pair and an
appropriate metal bal
‚Therefore, rate of base catalyzed bydolysis of red isomer of (Coren) (NH JC is much faster.
“The base catalysed hydrolysis of ed isomer of(Co(tren)(NH CU [Figure 7.1 1(2)] leads o attack of
Ayéroxide ion along any of los equal edges of TBP intermediate and fonns only one prodvt
{Figure 7.11(6)]. Thus byetolysis ofthe red isomer of (Co(teen)(NHs }CI]}?* leads to complete cetention
‘of configuration.
ai AT ENT
SS or ATX ye ENIAN
up | Ma] ÆN “nN
ha,
a,
o
|
SARA ae eT
Chelation and the steric hindrance increase the ae of base hydrolysis. The ate of base hydrolysis
high for diamines. I suggests hat reaction proceeds by dissociative mechanism.
Now let us consider rater of bes dl of [Cena LCI” complex ins wbereL = 1,
OH-,NOZ,CN et. E
QA rate of base Ilya of Ce) 20h 11s ste whereas the ae of tne Iosis al
“{Coler)s(802}C1)* aid TOHDCNO is slower than expected. The low ravi of
{Coen (NO2 )CN}* and [Co(en)2 (CNYCI]” complexes to base hydrolysis inspite of relatively larger
value of, cn be explana nto bass of bonding eet which shown blow
mimo
G
“The electron charge tha he amid group provides tothe cobalt atom i removed by sito group
du to M -> N bonding, Ths trucs the tendency of fable group to disociat. The ligand CN”
‘behaves similar o NOS buttoa lesser eat The lie ions do not undergo such bonding and ns
ase easily activated
(9 The rate of hydrolysis of [Co(py)4Cl]* or[CofCN)5CII”" is independent of OH concentration
‘because there is not protonic hydrogen in the two complexes.
@, Let us consider the base hydrolysis of the [Co(tren)(NH3 JCI]?* complex ion. The rate of base
‘hydrolysis depends upon deprotonation of the amino group trans to the leaving group. In other words,
{we can say that the proton of the amino group tráñs lo the leaving group play an important role in the rate.
‘of base hydrolysis. The (Coen}QNH JJ” ion exists in two isomeric forms having the red and the
purple colour. need iome, he Jing group istrans tothe — NE group Fi 7.40) ania
the purple isomer he leaving roup (ete halo group) i rans to the amino group which have no
proton Fig. 71005).
i a
hr Y
EN ENT
ANA TANT
LL ©
Fin: 7.19ated Rad some Mh Paule isomer.
‘The red isomer ofCoften}(NHs JC] ion is hydrolyzed much more faster than the purple isomer,
“The red isomer has a removable Pan onthe nitrogen atom ans to the leaving group. The
deprtanation of amino group by OF ion ads othe formation of igonal hipyrania intermedia
inthe dissociative (D) or interchange diciativ (1) mechanism. The ligand ten stabilizes the TB
intermediate by ligand's amido group to metal interaction between the NH” group lone pair and an
appropriate metal bal
‚Therefore, rate of base catalyzed bydolysis of red isomer of (Coren) (NH JC is much faster.
“The base catalysed hydrolysis of ed isomer of(Co(tren)(NH CU [Figure 7.1 1(2)] leads o attack of
Ayéroxide ion along any of los equal edges of TBP intermediate and fonns only one prodvt
{Figure 7.11(6)]. Thus byetolysis ofthe red isomer of (Co(teen)(NHs }CI]}?* leads to complete cetention
‘of configuration.
ai AT ENT
SS or ATX ye ENIAN
up | Ma] ÆN “nN
ha,
a,
o
|
On the other hand, the purple isomer of [Co(tec (NH; CI? [Figure 7.1 Kc) ion gives two
products he majo pdt (85%) same as hat obtained by the dis of there isomer, he her
oduct sony 15% This action cc through sqvrepyamial (SP) intermediate (Pire 7100)
"ich is unsble Some of hi taped and givens only 15% [igure 7.11] yield and he mjor
rearranges to give the major product 85% [Figure 7.11(9] which is given by the red isomer. The major
products buin, when the Hyde on atc from the site a he leaving group and he minar
Produ oui, we the bye ion stacks in the plane
Substitution Reactions without Breaking of Metak-ligand Bond
‘There are some reactions where ligand exchange takes place without cleavage ofthe mezalligand
bond instead bonds within the ligands themselves are broken and reformed. For example, in aid
solution, amminecarbonate complex of Co(ltl) like [Co(NHs)s(CO3)}* are converted to the
corespontingaqu complex{Co(NUts}5(H:0)]°* with release of CO. When the racionis caido
inthe presence of ¥0-abeled water in acidic medium (H3 !90)*, itis observed that abled MO goes
ino resul aque complex. Hence the Co—O bond must be reine during the couseof reaction.
HN)sCo —0C0,]° +2H''0* — (Fyn) sCotH,O)}* +21 "0 + CO,
Mechanlım:
‘hemos sabi mechanism fr his reaction involves piton ak on he oxygen ao bonded to
cobalt tom and CO, i then removed bythe cleavage of OC bord
oy Fast, oy
omrsor—o-e€9] aut ES lance 0€
© ‘OH.
E 2
o
Love u
o
L
5 (HN) soon?" +00,
are
LH); CO(OHL JP”
‘Thus this reaction a decarboxylation ater han an acid hydtalyrencion.
Similar mechanism bave been made for [Co(NH3)¿CO33* complex. In acidic medium
{Co(NHs}4C03]* kavingCO3” as bidentate ligand is converted to cis-[CNHs)3(E130)2]°*.In BO.
labeled water (HL *"O), half the oxygens in the product are derived from the solvent.
“The firs sep involves he cleavage of chelate ring (6.0, Co— band) nd one HO molecle fom
solvent nes no he coordination sphere. The second sep lik that [Co (CO; involves the
removal of CO} with cleavage of the O—C bond but without cleavage of the Co--O bond.
Now consider an natber reaction of formation ofa niit complex (El, 1) CO(ONO)P* fom its
comesprding ama comple, (As N)sCO(OH NP which takes place wir the breaking of
met igand bond
[CANIS )s (OH )]%" #NOZ—> [CONE )s(ONO?* +10
“This ection is very aid whic i itself suggests thatthe CoO bad isnt broken and can be
coatrmed by using labeled "Qin aqua complex.
[€38)sCo— “otf, P* +NO3 —> [(HjN)sCo— ONO} + HO
Mechanis:
Tn weekly aciicoluion, he nitossting agent is N 20 which teks the unshared pir of electrons
the amine isoge y spliting ino NO” and NOG. N20 is obtained by iscition oF HNO >.
HNO, 0, +10
Fa
(HIN) Co— OH PY + 420 (Hy) so OH + HO"
RICO — "om: N20; faros —Co— "o, a
2854458) 000! ONOY]+ HNO,
Ine asin ate ise O--H bond which broken but not a Co—O bond. Tus, oxygen of
the Higa einen ito Tiga.
STERIOCHEMISTRY OF ACID CATALYZED SUBSTITUTION REACTIONS
Icha led bre discussed that mos substitution reactions in other complexes proceed by
dissociative (D) ot interchange dissociative (A) mechanism through -coordiated species either square
pytamidal (SP) o-tigoal bipyramidal (TBP) intermediate (Figure 7.12)
4
products he majo pdt (85%) same as hat obtained by the dis of there isomer, he her
oduct sony 15% This action cc through sqvrepyamial (SP) intermediate (Pire 7100)
"ich is unsble Some of hi taped and givens only 15% [igure 7.11] yield and he mjor
rearranges to give the major product 85% [Figure 7.11(9] which is given by the red isomer. The major
products buin, when the Hyde on atc from the site a he leaving group and he minar
Produ oui, we the bye ion stacks in the plane
Substitution Reactions without Breaking of Metak-ligand Bond
‘There are some reactions where ligand exchange takes place without cleavage ofthe mezalligand
bond instead bonds within the ligands themselves are broken and reformed. For example, in aid
solution, amminecarbonate complex of Co(ltl) like [Co(NHs)s(CO3)}* are converted to the
corespontingaqu complex{Co(NUts}5(H:0)]°* with release of CO. When the racionis caido
inthe presence of ¥0-abeled water in acidic medium (H3 !90)*, itis observed that abled MO goes
ino resul aque complex. Hence the Co—O bond must be reine during the couseof reaction.
HN)sCo —0C0,]° +2H''0* — (Fyn) sCotH,O)}* +21 "0 + CO,
Mechanlım:
‘hemos sabi mechanism fr his reaction involves piton ak on he oxygen ao bonded to
cobalt tom and CO, i then removed bythe cleavage of OC bord
oy Fast, oy
omrsor—o-e€9] aut ES lance 0€
© ‘OH.
E 2
o
Love u
o
L
5 (HN) soon?" +00,
are
LH); CO(OHL JP”
‘Thus this reaction a decarboxylation ater han an acid hydtalyrencion.
Similar mechanism bave been made for [Co(NH3)¿CO33* complex. In acidic medium
{Co(NHs}4C03]* kavingCO3” as bidentate ligand is converted to cis-[CNHs)3(E130)2]°*.In BO.
labeled water (HL *"O), half the oxygens in the product are derived from the solvent.
“The firs sep involves he cleavage of chelate ring (6.0, Co— band) nd one HO molecle fom
solvent nes no he coordination sphere. The second sep lik that [Co (CO; involves the
removal of CO} with cleavage of the O—C bond but without cleavage of the Co--O bond.
Now consider an natber reaction of formation ofa niit complex (El, 1) CO(ONO)P* fom its
comesprding ama comple, (As N)sCO(OH NP which takes place wir the breaking of
met igand bond
[CANIS )s (OH )]%" #NOZ—> [CONE )s(ONO?* +10
“This ection is very aid whic i itself suggests thatthe CoO bad isnt broken and can be
coatrmed by using labeled "Qin aqua complex.
[€38)sCo— “otf, P* +NO3 —> [(HjN)sCo— ONO} + HO
Mechanis:
Tn weekly aciicoluion, he nitossting agent is N 20 which teks the unshared pir of electrons
the amine isoge y spliting ino NO” and NOG. N20 is obtained by iscition oF HNO >.
HNO, 0, +10
Fa
(HIN) Co— OH PY + 420 (Hy) so OH + HO"
RICO — "om: N20; faros —Co— "o, a
2854458) 000! ONOY]+ HNO,
Ine asin ate ise O--H bond which broken but not a Co—O bond. Tus, oxygen of
the Higa einen ito Tiga.
STERIOCHEMISTRY OF ACID CATALYZED SUBSTITUTION REACTIONS
Icha led bre discussed that mos substitution reactions in other complexes proceed by
dissociative (D) ot interchange dissociative (A) mechanism through -coordiated species either square
pytamidal (SP) o-tigoal bipyramidal (TBP) intermediate (Figure 7.12)
4
CE Te CE
rez
Letus consider the substitution reactions of is and ran-isomen offCofen)CIYI”* with KO.
‘The substitution reaction in eis{Colen)2CIV?* with 1,0 proceeds through S-coortinate
squarepyamidal intermediate (Con) VI)" 10 give cisfCofea),¥(HO)}* because the
squarepyranial intermediate has a single ste for atac by #70. (Figure 7.13] Tos, hydrolysis ofeis-
Go) GAY ype complex ion feas 1 complete retention of configuration.
ok) alley = ok
Stator atack i re
Ro
ae za
The subs reaction of CL in crans4{Cafen),CIYY by #0 proceeds though S-coordinte
trigonal bipyramidal intermediate to give mixture of is an trans some of (Coen) 2Y(H20))*
Figure 7.14] because HO molecule can attack the trigonal bipyramidal intermediate at all ofthe three
sites in the euqatrial plan, ICY is a good s-donor, then form z bond wifh metal cation and stabilizes
the TBP intermediate In this case the substtuipn occurs definitly trough TBP intermediate,
Figs za:
In gener, ros complexes of the (pe Cole) CIYI* undergo seachemical change upon
Ihyrolysis whereas cis-complexes of the type [Colen)2CIY]?* undergo hydrolysis with retention ofthe
Inger cs-somerseact more fase than he rans isomers. The gan Y (rans having
io) tat leads fo steriochemical change i ras homer ar ta wth lone pairs of prelectrns
‘Tea pa ica inc trough gard to meal bonding wih an empty meal oil and
sable TBP iatemediate (Fig. 7.15)
:
t 4 Ti
ta, a 1%
A on,
N
ty Top memes
Betas,
rez
Letus consider the substitution reactions of is and ran-isomen offCofen)CIYI”* with KO.
‘The substitution reaction in eis{Colen)2CIV?* with 1,0 proceeds through S-coortinate
squarepyamidal intermediate (Con) VI)" 10 give cisfCofea),¥(HO)}* because the
squarepyranial intermediate has a single ste for atac by #70. (Figure 7.13] Tos, hydrolysis ofeis-
Go) GAY ype complex ion feas 1 complete retention of configuration.
ok) alley = ok
Stator atack i re
Ro
ae za
The subs reaction of CL in crans4{Cafen),CIYY by #0 proceeds though S-coordinte
trigonal bipyramidal intermediate to give mixture of is an trans some of (Coen) 2Y(H20))*
Figure 7.14] because HO molecule can attack the trigonal bipyramidal intermediate at all ofthe three
sites in the euqatrial plan, ICY is a good s-donor, then form z bond wifh metal cation and stabilizes
the TBP intermediate In this case the substtuipn occurs definitly trough TBP intermediate,
Figs za:
In gener, ros complexes of the (pe Cole) CIYI* undergo seachemical change upon
Ihyrolysis whereas cis-complexes of the type [Colen)2CIY]?* undergo hydrolysis with retention ofthe
Inger cs-somerseact more fase than he rans isomers. The gan Y (rans having
io) tat leads fo steriochemical change i ras homer ar ta wth lone pairs of prelectrns
‘Tea pa ica inc trough gard to meal bonding wih an empty meal oil and
sable TBP iatemediate (Fig. 7.15)
:
t 4 Ti
ta, a 1%
A on,
N
ty Top memes
Betas,
ACA RN es ROO! EAN
ER
“Therefore, the x-donor ligands such asCI”, Br“,
termediate and favour the sleriochemical change.
(nthe other hand, the substitution reaction in cisisomer[Col VX] with H30 proceeds through
coordinate squarepyramidal intermediate [Col YJ"*Ü* and the pr-lone pairs of electrons onthe
ligand stabilize the squarepyramidal intermediate by interaction with the metal porbital previously
eoocupied with o-bonding Lo the leaving group without rearrangement and the reaction will be more
ste since there is no need for carrangement
/-bonded NOS”, NHG ete stabilize the TBP
‘The greatest aumber of square planar complexes usually ocur with transition metal ions of d*
con configuration. These include complexes of Nil), PA), Pl), RQ), IT) and Au(UD.
are planar complexes of PtH) have been extensively studied and analysed because (i) square planar
mplexes of Pil) ace most stable, (i) easy to synthesise, (ii) Pt (ID complexes of CN. 4 ae lays:
are plane uke Ni (1) complexes which form trahedral complexes with weak ligands and square
mar complexes with strong ligands, (iv) substition reactions in PI complenes undergo at slow
es and ar, therefore, conveniea for laboratory study
Ligand substitution reactions in Ni) and PA) square planar complexes undergo 10° and 107
es more tapily than PUI) complexes respectively.
‘As we have discussed carle thatthe sbsthuion reactions in octahedral complexes proceed by
sciative (SN!) mechnism but the square planer complexes undergo substitution reactions by
oviative (SN?) mechanism. When square planar complexes of PUI undergo substtuion reactions
iszetention of configuration Le, cs-somer gives cis product and trans isomer gives trans produc.
s observation suggests that Pt (1) square planar complexes donot undergo substitution reactions by
ocative mechanism,
tors Affecting Rates of Substitution Reactions in Square Planar Complexes of P(t)
Serer factors that affect the sectiviy of quar planar complexes are
(1) Natur of Entering Ligand (2) Nature of Leaving Group
@) Charge Effect (4) tere Pee of Non-feaving Ligand >
(65) Solvent Effect (6 Trans Effet
(0) Nature of Entering Ligand : We know tat the equilibrium constant of substiuion reactions
be used o rank ligands in order of hir basicity (e, strength as Lewis base). Thus, best ls a
modyaamic property and itis measured in tem of p£ of conjugate acid of a Lewis base.
Rates of reactions that proceed by an associative mechanism is strongly dependent on the
pli ofthe entering group or ligand, Nuceopbilicity ofan eteing ligand isthe measure of ts
rate of attack on a complex in nucleophilic subsittion reactions implies that nucleopiliciy
Kinetic term. The nucteophilicity is parallel but not necessarily equivalent to basicity Le
opti character ofthe reagents does not create et basic Bsicity is of Tes importance but
rirabifty plays an important role in determining the ceacivity of the ligand. Further, the
iabili of ligand i always more important for cates han foc equltria. Now according to SHAB
ip, soft (polarizable) ligands are more eficiv towards soft substrates (i.e, complexes) and
larly hard ligands like OH” are more effective towards bard substrates,
or Pl) squc planar complens, sine PA) sso subst, hs more palaizabie ligand e
pod ucleophiles.
Ineeasng ower of nucleophiles of some gend for PD) square planar complex is:
OH” < HO <CI” ~ Nits —akenoCoHsNH <pyttine< Br” < NOG < NZ
SONT =I" << RS
Finally more is th mucleopilcy of an enteing gan higher wit be the rate of sbstition
reso by associative mechanism and vio sra.
Nature leaving Group: Teto pops ben tlie inthe flowing acon
Le Pe" +X 0)
Incomplex (Piden), tire coria poston ae occupied by he net ligan, dien and
entro ga salvas pyridine (py). Th varie the above action sony °° (Le, the leaving
ligand, As” igand is changed, rato acon isl changed. The value of ae constants for
various leaving ligands inte reaction) are given in be Table 73,
Table 7.3: Rato Constants for the Reaction ()
CE ooo
E Very fast
ES
ES
Le on
ae a
no; os
or on
“The observed rate constants for vacios leaving ligands suggest the following order of rate of
reaction: Ñ
NO3 > HO > CI > Be” >1">N5 > SCN™ > NOS > CN’
This oder of ate of reaction indicate thatthe eving group has significant eet on the ae of
reaction. It also indicates that considerable PK bond breaking is involved in forming he transition
state anditis observed that Pt—¥ bond breakiogmake a contribution comparable o thet ofthe formation
Rp bond
(9 Charge Eset: Matin eral has bon stu Iosis ofthe series of complexes [PIC
RUNES ICT [PHONE )2Cla} and (PANE) SC” wi charge varying from —2 10 H (ie, 3 wait
change in charge on complez) It was observed that ae of bydrlysis of these four completes are
seqoinately same (ay ony by aftr oft). Thi rg illes in charges bt he
xremarable small variation in heats. The PCI Bond breaking should bore dificult in cam
ER
“Therefore, the x-donor ligands such asCI”, Br“,
termediate and favour the sleriochemical change.
(nthe other hand, the substitution reaction in cisisomer[Col VX] with H30 proceeds through
coordinate squarepyramidal intermediate [Col YJ"*Ü* and the pr-lone pairs of electrons onthe
ligand stabilize the squarepyramidal intermediate by interaction with the metal porbital previously
eoocupied with o-bonding Lo the leaving group without rearrangement and the reaction will be more
ste since there is no need for carrangement
/-bonded NOS”, NHG ete stabilize the TBP
‘The greatest aumber of square planar complexes usually ocur with transition metal ions of d*
con configuration. These include complexes of Nil), PA), Pl), RQ), IT) and Au(UD.
are planar complexes of PtH) have been extensively studied and analysed because (i) square planar
mplexes of Pil) ace most stable, (i) easy to synthesise, (ii) Pt (ID complexes of CN. 4 ae lays:
are plane uke Ni (1) complexes which form trahedral complexes with weak ligands and square
mar complexes with strong ligands, (iv) substition reactions in PI complenes undergo at slow
es and ar, therefore, conveniea for laboratory study
Ligand substitution reactions in Ni) and PA) square planar complexes undergo 10° and 107
es more tapily than PUI) complexes respectively.
‘As we have discussed carle thatthe sbsthuion reactions in octahedral complexes proceed by
sciative (SN!) mechnism but the square planer complexes undergo substitution reactions by
oviative (SN?) mechanism. When square planar complexes of PUI undergo substtuion reactions
iszetention of configuration Le, cs-somer gives cis product and trans isomer gives trans produc.
s observation suggests that Pt (1) square planar complexes donot undergo substitution reactions by
ocative mechanism,
tors Affecting Rates of Substitution Reactions in Square Planar Complexes of P(t)
Serer factors that affect the sectiviy of quar planar complexes are
(1) Natur of Entering Ligand (2) Nature of Leaving Group
@) Charge Effect (4) tere Pee of Non-feaving Ligand >
(65) Solvent Effect (6 Trans Effet
(0) Nature of Entering Ligand : We know tat the equilibrium constant of substiuion reactions
be used o rank ligands in order of hir basicity (e, strength as Lewis base). Thus, best ls a
modyaamic property and itis measured in tem of p£ of conjugate acid of a Lewis base.
Rates of reactions that proceed by an associative mechanism is strongly dependent on the
pli ofthe entering group or ligand, Nuceopbilicity ofan eteing ligand isthe measure of ts
rate of attack on a complex in nucleophilic subsittion reactions implies that nucleopiliciy
Kinetic term. The nucteophilicity is parallel but not necessarily equivalent to basicity Le
opti character ofthe reagents does not create et basic Bsicity is of Tes importance but
rirabifty plays an important role in determining the ceacivity of the ligand. Further, the
iabili of ligand i always more important for cates han foc equltria. Now according to SHAB
ip, soft (polarizable) ligands are more eficiv towards soft substrates (i.e, complexes) and
larly hard ligands like OH” are more effective towards bard substrates,
or Pl) squc planar complens, sine PA) sso subst, hs more palaizabie ligand e
pod ucleophiles.
Ineeasng ower of nucleophiles of some gend for PD) square planar complex is:
OH” < HO <CI” ~ Nits —akenoCoHsNH <pyttine< Br” < NOG < NZ
SONT =I" << RS
Finally more is th mucleopilcy of an enteing gan higher wit be the rate of sbstition
reso by associative mechanism and vio sra.
Nature leaving Group: Teto pops ben tlie inthe flowing acon
Le Pe" +X 0)
Incomplex (Piden), tire coria poston ae occupied by he net ligan, dien and
entro ga salvas pyridine (py). Th varie the above action sony °° (Le, the leaving
ligand, As” igand is changed, rato acon isl changed. The value of ae constants for
various leaving ligands inte reaction) are given in be Table 73,
Table 7.3: Rato Constants for the Reaction ()
CE ooo
E Very fast
ES
ES
Le on
ae a
no; os
or on
“The observed rate constants for vacios leaving ligands suggest the following order of rate of
reaction: Ñ
NO3 > HO > CI > Be” >1">N5 > SCN™ > NOS > CN’
This oder of ate of reaction indicate thatthe eving group has significant eet on the ae of
reaction. It also indicates that considerable PK bond breaking is involved in forming he transition
state anditis observed that Pt—¥ bond breakiogmake a contribution comparable o thet ofthe formation
Rp bond
(9 Charge Eset: Matin eral has bon stu Iosis ofthe series of complexes [PIC
RUNES ICT [PHONE )2Cla} and (PANE) SC” wi charge varying from —2 10 H (ie, 3 wait
change in charge on complez) It was observed that ae of bydrlysis of these four completes are
seqoinately same (ay ony by aftr oft). Thi rg illes in charges bt he
xremarable small variation in heats. The PCI Bond breaking should bore dificult in cam
with higher positive charge and alo, in the complexes with higher positive charge, the ligand
“approaches easily. The discussion indicates that Pt—Cl bond breaking and Pt—OH) bond making both
are of equal importance and the rection proceed by associative (A) or interchange associative (ls)
seckanism.
(4) Sterie Effet of Non-eaving Ligands : The octahedral complexes are closed to mcleopilic
attack and whereas square planar complexes are open io nucleophilic attack. Thus, octahedral complexes
ndergo substitution reactions by dissociation mechanism and the square planar complexes undergo
substitution reactions by associative (GN?) mechanism. Af steric hindrance increases, he rte oF
substitution in octahedral complexes increases because steric hindrance favours the dissociation. Bulky
groups block the approach of atckig ligand. The dissociative reaction reduces the coordination
number and the overcrowding decreases,
In square planar complexes, since the subsitution reaction proceeds by associative mechanism,
therefore, steric hindrance decreases the ate of reaction because the overcrowding oppases the
increasing of coordination number (, formation of intrmate or transition state of CNS),
“The rate constants observed for hydroJ es of ci nd rans [Pt(PEL a LCH ae shown below:
e ine dim
Pyridine 2-methyl pyri a
For eis Rate constants (6) B10? 20x104 10x10%
For trans 120t o 34406
In ciscomplex, when Ls pyridine tee is Les crowding and rte of hydrolysis faster. When L
is 2-methyipyridio Le, the methyl group s afacen of N-donor atom, it increase the comding and
hence decreases thera. In 2-methy pyridis complex, the methyl group are either above or below the
plane and thus shields the PAI) either above or below the square plane. In 2,-dinedhypyidine
Complex, crowding fuer increases near the Nedoor atom and hence again the rate decreases. The
‘mel groups block the positions above and below th plane. The effect of steric hindrances smaller if
Lis tenso CU
45) Solvent Effet + It has ben observed thatthe solvent path for square planar substation
involves direct replacement of” by the solvent. f there isan increase in coordination silty of the
solvent with meta! cation, then the contbaion made by this path tothe overall ate of reaction wuld
also increases, This i in accondoee with he experimental results of the solveat effet onthe rate of
26C1" exchange wih trans {P(py) Ch complex Aes of solvent on the rate of “CI exchange with
srans-{P(py)2Cla is given in Table 7.4
‘Under the expermenal conditions, vi. moderately Yow concentration of CI”, the solvents re
divided into two categories
(1) The good coondinaig solvents like DMSO, HO,ROH ete which provide almost entirely a
solvent path for exchange , >> (CT) Fo thse solvent, te rte of exchange is independent of
ACT 3 For good solver, the vale of Ky inressesin the onder: ROH <H,0~ CHsNO, <DMSO.The
rate of exchange is faster in DMSO than in water.
Tiesto nia Rag
sis Independent of (CL
DMSO
1,0
CHyNO,
CoHsOH
(i) Te poor coordinan ligands such as OC, Ca, steialy hindered alcohol ee which
contribute ite tothe over ae festin, For thse solvents, the rate of exchange depends onthe
concentration of CI”
(6) Trans Ese: Ligands ober dan he entecing und leaving groups ay ax the te of
substntion rein. A ligand which not ot e reaction is called pet ligan.
“The effect spectator ligand coordinated to metal cation upon the rate of subt of ligands
trons tis called ran fet
‘Chater afhavesogetsts that te ons ff second or group tacho areal ton
isthe tendeny ft gon o dica cing rulo oc) he position ia ot group.
“The spectator ligand ar group which des an incoming ligand to occupy the poston rans tits
called ran directing group na er.
"Now consider te substiion ration ia square planar complex, tans ML; in which Lisa
spectator (or on-leving) group ads Li à kaving gov.
the ligand X rant gend is replaced ply by another ligand Y o give MLX then Lis
sait have ne ibiiingefect oros blico, Since the ligand Lmakes he ügnd bil rans
toitso th rans ft alo ald a iin et
x
Ne us it
EN TE ged Mo
The
(High end) EN” CO,NO CoH PRS, ASR, 0
SON" > Br > CI” >py> RN NE > F" > OH” > H20 (low end)
“The series given above is called ans dict eres.
‘The ligansfikeCN~,0,NO,CaHg ying othe highend ae racer andre son rans
diretrs On the the tante ligand OH, HO}ying on weak end ace very poor ns dicos
A tong trans dire as the silty o promotes more api substation ofthe ined uns o
selfthan does of i ganó oto ell.
‘The trans effec isa Kina phenomenon because ans effect ofa figand L promis the pid
substitution find Gran”
“The ans ffx (ie, ei ans ei diffeentisted from ens iniuene, The an intense
isa thermodynamic phenomenon, e, ligands cn influence the ground state ropes of ligando
Weich ey are tano sich asthe ons bond tun othe vibrational reno: Forsanple A
“approaches easily. The discussion indicates that Pt—Cl bond breaking and Pt—OH) bond making both
are of equal importance and the rection proceed by associative (A) or interchange associative (ls)
seckanism.
(4) Sterie Effet of Non-eaving Ligands : The octahedral complexes are closed to mcleopilic
attack and whereas square planar complexes are open io nucleophilic attack. Thus, octahedral complexes
ndergo substitution reactions by dissociation mechanism and the square planar complexes undergo
substitution reactions by associative (GN?) mechanism. Af steric hindrance increases, he rte oF
substitution in octahedral complexes increases because steric hindrance favours the dissociation. Bulky
groups block the approach of atckig ligand. The dissociative reaction reduces the coordination
number and the overcrowding decreases,
In square planar complexes, since the subsitution reaction proceeds by associative mechanism,
therefore, steric hindrance decreases the ate of reaction because the overcrowding oppases the
increasing of coordination number (, formation of intrmate or transition state of CNS),
“The rate constants observed for hydroJ es of ci nd rans [Pt(PEL a LCH ae shown below:
e ine dim
Pyridine 2-methyl pyri a
For eis Rate constants (6) B10? 20x104 10x10%
For trans 120t o 34406
In ciscomplex, when Ls pyridine tee is Les crowding and rte of hydrolysis faster. When L
is 2-methyipyridio Le, the methyl group s afacen of N-donor atom, it increase the comding and
hence decreases thera. In 2-methy pyridis complex, the methyl group are either above or below the
plane and thus shields the PAI) either above or below the square plane. In 2,-dinedhypyidine
Complex, crowding fuer increases near the Nedoor atom and hence again the rate decreases. The
‘mel groups block the positions above and below th plane. The effect of steric hindrances smaller if
Lis tenso CU
45) Solvent Effet + It has ben observed thatthe solvent path for square planar substation
involves direct replacement of” by the solvent. f there isan increase in coordination silty of the
solvent with meta! cation, then the contbaion made by this path tothe overall ate of reaction wuld
also increases, This i in accondoee with he experimental results of the solveat effet onthe rate of
26C1" exchange wih trans {P(py) Ch complex Aes of solvent on the rate of “CI exchange with
srans-{P(py)2Cla is given in Table 7.4
‘Under the expermenal conditions, vi. moderately Yow concentration of CI”, the solvents re
divided into two categories
(1) The good coondinaig solvents like DMSO, HO,ROH ete which provide almost entirely a
solvent path for exchange , >> (CT) Fo thse solvent, te rte of exchange is independent of
ACT 3 For good solver, the vale of Ky inressesin the onder: ROH <H,0~ CHsNO, <DMSO.The
rate of exchange is faster in DMSO than in water.
Tiesto nia Rag
sis Independent of (CL
DMSO
1,0
CHyNO,
CoHsOH
(i) Te poor coordinan ligands such as OC, Ca, steialy hindered alcohol ee which
contribute ite tothe over ae festin, For thse solvents, the rate of exchange depends onthe
concentration of CI”
(6) Trans Ese: Ligands ober dan he entecing und leaving groups ay ax the te of
substntion rein. A ligand which not ot e reaction is called pet ligan.
“The effect spectator ligand coordinated to metal cation upon the rate of subt of ligands
trons tis called ran fet
‘Chater afhavesogetsts that te ons ff second or group tacho areal ton
isthe tendeny ft gon o dica cing rulo oc) he position ia ot group.
“The spectator ligand ar group which des an incoming ligand to occupy the poston rans tits
called ran directing group na er.
"Now consider te substiion ration ia square planar complex, tans ML; in which Lisa
spectator (or on-leving) group ads Li à kaving gov.
the ligand X rant gend is replaced ply by another ligand Y o give MLX then Lis
sait have ne ibiiingefect oros blico, Since the ligand Lmakes he ügnd bil rans
toitso th rans ft alo ald a iin et
x
Ne us it
EN TE ged Mo
The
(High end) EN” CO,NO CoH PRS, ASR, 0
SON" > Br > CI” >py> RN NE > F" > OH” > H20 (low end)
“The series given above is called ans dict eres.
‘The ligansfikeCN~,0,NO,CaHg ying othe highend ae racer andre son rans
diretrs On the the tante ligand OH, HO}ying on weak end ace very poor ns dicos
A tong trans dire as the silty o promotes more api substation ofthe ined uns o
selfthan does of i ganó oto ell.
‘The trans effec isa Kina phenomenon because ans effect ofa figand L promis the pid
substitution find Gran”
“The ans ffx (ie, ei ans ei diffeentisted from ens iniuene, The an intense
isa thermodynamic phenomenon, e, ligands cn influence the ground state ropes of ligando
Weich ey are tano sich asthe ons bond tun othe vibrational reno: Forsanple A
004 trans- directing ligand weaken the bond between the metal and the guns figaod. The trans
flueocs is shown in the following complexes
238 pn 23pm 22m
a | a a | ci
Sn Sal
CAS
En” Sa 11 el Sa
Cth
o o
From the complexes (a), (0) and (c) itis observed that
EtsP> CH = CH > Cl" .
pplications of Trans Effect
Most of the work on rans effect has been done on square planar complexes of PU).
‘Thetrans effects very wsefilia the synthesis of large number of square plana complexes of PAD,
1. Synthesis of es and rans-[PHNH )2Cla}:
‘The synthesis of ef-{P(NH3 )2Cla] is carried out by treatment ofthe PtClg > ion wth ammonia,
a à
fa, al NE; NH
NPA CNE ON
Pr Pr Bal
a” Na Lo Sa] la Nm
nome
inte sco poc mona opi eb pasion eun 2
greater than that of ammonia. ” ms Greene
Temeans thatthe least reactive” in {PQNH)2Cla J is rast armonia.
‘The synthesis of rans (PIN) ¿Cl is carried out by the treating [PYNHs JJ?" with CI
Br NT ae, [inc co, [Ja
NE EN” Sam a Nam
ns]
Tn the above reaction Cl” replaces most labile NH; in[PUNE3 )2Cl; ]* which is rans toCI" ‘group
hs resus inthe formation of ans [PUNA )2Ciz]
2. Synthesis of ci and rans41(NH (NO; CH Lon
‘The synthesis of ci and ans isomers of IPN XNO ly
ity fC”, Nig and NO3 groups which sin the order of:
NO} > CI" > Ny
ANSE
TST:
‘The some is repre by the action of NH on [PICIa]” followed by NOS group.
2 - E
y A 9 NA a EN
a” Nal la” Na | Ta” Nvo,
PUS
On the other band, trans isomer is obtained by testing [PICI,J with NO} followed by NES
group
fa al ugg [ON NOT CE
Seal TN ml Ned
a” <A la Na lo Na
re (PONT
5. Synthesis cis. and trans. [PU(C Hg (NH )CIa]
‘The synthesis of it~ and wrans- isomers of (PUCH YO Jas based on the ran dceting
ability of CH, NH and ligands whichis in the order of:
Ñ Cylig> CI” > NH
The cisdsomers prepare by treating [PLCI, with NH followed by CH.
Pa nn] Ni,
LY EI y ET [ON y,
a” Nal “la Na | + ja? Now
EICHE
“The eran eames prepared by eating [PCA F with C2H, followed by NH
P a CH
ay 2H
Sal
a” Na Ne Na
"cm [N HET cs
a’ Ya
rau C03)
A Synthesis ae andra omer of {PPR )2Cla
‘Sine ns efecto is greater han that of CI, therefore, anses ota by testing
[Pt with PR sa follows
2
fon a
a” Na
fo PRs CS
Ne’ AS
a” Na | me” Na
ten)
flueocs is shown in the following complexes
238 pn 23pm 22m
a | a a | ci
Sn Sal
CAS
En” Sa 11 el Sa
Cth
o o
From the complexes (a), (0) and (c) itis observed that
EtsP> CH = CH > Cl" .
pplications of Trans Effect
Most of the work on rans effect has been done on square planar complexes of PU).
‘Thetrans effects very wsefilia the synthesis of large number of square plana complexes of PAD,
1. Synthesis of es and rans-[PHNH )2Cla}:
‘The synthesis of ef-{P(NH3 )2Cla] is carried out by treatment ofthe PtClg > ion wth ammonia,
a à
fa, al NE; NH
NPA CNE ON
Pr Pr Bal
a” Na Lo Sa] la Nm
nome
inte sco poc mona opi eb pasion eun 2
greater than that of ammonia. ” ms Greene
Temeans thatthe least reactive” in {PQNH)2Cla J is rast armonia.
‘The synthesis of rans (PIN) ¿Cl is carried out by the treating [PYNHs JJ?" with CI
Br NT ae, [inc co, [Ja
NE EN” Sam a Nam
ns]
Tn the above reaction Cl” replaces most labile NH; in[PUNE3 )2Cl; ]* which is rans toCI" ‘group
hs resus inthe formation of ans [PUNA )2Ciz]
2. Synthesis of ci and rans41(NH (NO; CH Lon
‘The synthesis of ci and ans isomers of IPN XNO ly
ity fC”, Nig and NO3 groups which sin the order of:
NO} > CI" > Ny
ANSE
TST:
‘The some is repre by the action of NH on [PICIa]” followed by NOS group.
2 - E
y A 9 NA a EN
a” Nal la” Na | Ta” Nvo,
PUS
On the other band, trans isomer is obtained by testing [PICI,J with NO} followed by NES
group
fa al ugg [ON NOT CE
Seal TN ml Ned
a” <A la Na lo Na
re (PONT
5. Synthesis cis. and trans. [PU(C Hg (NH )CIa]
‘The synthesis of it~ and wrans- isomers of (PUCH YO Jas based on the ran dceting
ability of CH, NH and ligands whichis in the order of:
Ñ Cylig> CI” > NH
The cisdsomers prepare by treating [PLCI, with NH followed by CH.
Pa nn] Ni,
LY EI y ET [ON y,
a” Nal “la Na | + ja? Now
EICHE
“The eran eames prepared by eating [PCA F with C2H, followed by NH
P a CH
ay 2H
Sal
a” Na Ne Na
"cm [N HET cs
a’ Ya
rau C03)
A Synthesis ae andra omer of {PPR )2Cla
‘Sine ns efecto is greater han that of CI, therefore, anses ota by testing
[Pt with PR sa follows
2
fon a
a” Na
fo PRs CS
Ne’ AS
a” Na | me” Na
ten)
‘The cis-isomer of PH(PR3 )2 las obtained by treating [PR sP)4}* with CI as follows :
Re ¿O
a Sa
>
RPL PR
Neg)
rl
RER)
5.Spathess of Isomer of(PUNH PYJCH
‘The order of ransdireeing ability of NH, Py, CI” and Br” is, Be” > CI” > Py > NH and the
order of bond strength is Pt-NHs > Pt- Py > Pt-Br > Pt-CL These two fics govern the synthesis of
‘three isomers of [PUN XPy)CIBr}.
IAE IAE ENS
la a] aa FANS Fr fa M5,
Ve Be ised PUNE CL ne ft anda ns CT ised pil an the
product so formed is (Pt(NH3 BrCl] rather than [PiBeC1;]?” because of greater Pt-NH3 bond
strength, Now when Py is added to cis{P(NH3)BrClz] , the CI” trans to Br” is replaced by Py
Secs: of et ran to Br
‘The second isomer of(PUNHy XPyICIBA]” is prepared as follows using the concept of trans effect.
ES
aa] Ta
‘The this isomer of {Pt(NHs KPY)CIBE prepared as follows
eT
aa
ut, JON
= |a/ Np.
ES
=o
la,
Sag
a pe
fa yal PF] yf
Sed Val |,
lo Kel Spy) a
Inthe second step ofthis reaction the substitution is controlo byte ability of chloride whereas in
(he third step is controlled by higher trans effet of
Inthis reaction, the second step is seen tobe against the tans effect otitis nots, The trans effect
does not predict that any ligand trans 0CI should berepacad more rapidly than any ligan trans to Py
ut a CI” tans to Cl” will be replaced more rapid tan a CI” trans to Py if there is an ambigity
{orchoice) but het, her is mo choice. In the lst step if we kaow tat Br” isthe entering and Py is the
‘caving group, then trans effect predicts the replacement ofthe Py rans CT"
To Distinguish between cis- and trans-Isomers of[P1A2X2] Complexes :
‘The trans fica as also been used by Russian chemists to distinguish between cis- and trans-
isomers ofthe [PA2X 2] type complexes (where A = NE or amine group ané X = an anion like
CI”, Br” ete) For example : cisfPU(NH))aClo] eats wit our), H3NCSNH; to give
{Papa} whereas under the same condition the sans [PUNT Ch gives (PL) Cla}.
This test is known as the Kumakov test. This test works for [PYNH3)2X2] complexes
X" = belies) because the tans effet of dis greater than hat of amine and halide ion.
AA A me Pa Tay
O EN O ERAS
Dx ar Dr = fo]
HN he
EN, a sos ka Inc“ se Rn," &
ca as} = | ANT
mire) ;
In the ciscomplex, he ammonie molecules ae labile bythe ansaid ins an,
«moni meleeul are replaced by two dires molecules, Now te Halle ions ron to thiourea
molecules ae bled and these lies ar als replaced by tetra molecules. Hence all the
asis are occupied by thiura. Inthe ans. comple, be hid ons biz eachother and,
Were, ony thse ligands ae replaced by thiourea moles
‘Similar results have becn reported for reactions of thosulphate (520% ion instead of tu, cis- and
trons (PUN )ACIz] feats with excess of 820% ion to form [PUSZOS)4P" and
{P43 (520,5) }respectively.
THEO!
Several theories have been given forthe explanation ofthe ans cit The two important theories
presenting different approaches are discussing hee
(1) The Polarization Theory
‘Tis theory was developed by Grinberg (1927) o explain the rans effect end iss thermodynamic
approach, The trans ircting ability of a igamd i late to is poliza. According 0 his theory
the large vans effect of L in {PtAaLX] complex cesabilie the ground state by weakening the
smealdigand bond (te, the MX bond) trans o el, The weakening of MX bond trans to L
decreases the activation energy (the diference in energy between dc ground sate and the transition
ste) and the ate of reaction is increased,
Re ¿O
a Sa
>
RPL PR
Neg)
rl
RER)
5.Spathess of Isomer of(PUNH PYJCH
‘The order of ransdireeing ability of NH, Py, CI” and Br” is, Be” > CI” > Py > NH and the
order of bond strength is Pt-NHs > Pt- Py > Pt-Br > Pt-CL These two fics govern the synthesis of
‘three isomers of [PUN XPy)CIBr}.
IAE IAE ENS
la a] aa FANS Fr fa M5,
Ve Be ised PUNE CL ne ft anda ns CT ised pil an the
product so formed is (Pt(NH3 BrCl] rather than [PiBeC1;]?” because of greater Pt-NH3 bond
strength, Now when Py is added to cis{P(NH3)BrClz] , the CI” trans to Br” is replaced by Py
Secs: of et ran to Br
‘The second isomer of(PUNHy XPyICIBA]” is prepared as follows using the concept of trans effect.
ES
aa] Ta
‘The this isomer of {Pt(NHs KPY)CIBE prepared as follows
eT
aa
ut, JON
= |a/ Np.
ES
=o
la,
Sag
a pe
fa yal PF] yf
Sed Val |,
lo Kel Spy) a
Inthe second step ofthis reaction the substitution is controlo byte ability of chloride whereas in
(he third step is controlled by higher trans effet of
Inthis reaction, the second step is seen tobe against the tans effect otitis nots, The trans effect
does not predict that any ligand trans 0CI should berepacad more rapidly than any ligan trans to Py
ut a CI” tans to Cl” will be replaced more rapid tan a CI” trans to Py if there is an ambigity
{orchoice) but het, her is mo choice. In the lst step if we kaow tat Br” isthe entering and Py is the
‘caving group, then trans effect predicts the replacement ofthe Py rans CT"
To Distinguish between cis- and trans-Isomers of[P1A2X2] Complexes :
‘The trans fica as also been used by Russian chemists to distinguish between cis- and trans-
isomers ofthe [PA2X 2] type complexes (where A = NE or amine group ané X = an anion like
CI”, Br” ete) For example : cisfPU(NH))aClo] eats wit our), H3NCSNH; to give
{Papa} whereas under the same condition the sans [PUNT Ch gives (PL) Cla}.
This test is known as the Kumakov test. This test works for [PYNH3)2X2] complexes
X" = belies) because the tans effet of dis greater than hat of amine and halide ion.
AA A me Pa Tay
O EN O ERAS
Dx ar Dr = fo]
HN he
EN, a sos ka Inc“ se Rn," &
ca as} = | ANT
mire) ;
In the ciscomplex, he ammonie molecules ae labile bythe ansaid ins an,
«moni meleeul are replaced by two dires molecules, Now te Halle ions ron to thiourea
molecules ae bled and these lies ar als replaced by tetra molecules. Hence all the
asis are occupied by thiura. Inthe ans. comple, be hid ons biz eachother and,
Were, ony thse ligands ae replaced by thiourea moles
‘Similar results have becn reported for reactions of thosulphate (520% ion instead of tu, cis- and
trons (PUN )ACIz] feats with excess of 820% ion to form [PUSZOS)4P" and
{P43 (520,5) }respectively.
THEO!
Several theories have been given forthe explanation ofthe ans cit The two important theories
presenting different approaches are discussing hee
(1) The Polarization Theory
‘Tis theory was developed by Grinberg (1927) o explain the rans effect end iss thermodynamic
approach, The trans ircting ability of a igamd i late to is poliza. According 0 his theory
the large vans effect of L in {PtAaLX] complex cesabilie the ground state by weakening the
smealdigand bond (te, the MX bond) trans o el, The weakening of MX bond trans to L
decreases the activation energy (the diference in energy between dc ground sate and the transition
ste) and the ate of reaction is increased,
“Fhe este to which a ligand affects the ground ste properties such as metal (ligand band
sane, the vibrational frequency and coupling constant ans o ein a complex is called he rans
uence
Let us consider the following 5% ps of square planar complexes of PI) 0 understand this
peony
@ PeX a Type Complex: Acsordi bs theory the PAI) ction induces dipole in al the four
gands Since al the four igands(. ligands trons to one anther) ace same, therefoe, he induced
pole af one ligand is cancelled by he dipole ofits mans Hand and thus te resultant dipole is ze.
Figure 7.16) Hence none of the fou ligund hop trans eet
(0 1PELX 1] Type Complex : Te ray charge on Pr ion induces a diple in al the four
Iganés, The dipole in uo X ligands Which are sini and trans to each other balance each other Thus,
1 ofthese two ligands do aot show ras effet. Onthe ober hand, the two ligands L'an X which re
ras 6 each or do not because Lis larger and has greater polarizability than X. The et cest is that
primary charge on Pi indüces a dile in L which in tum induces dipole ia PI, Tn aer
or, can ey that Pi} and L bth becomes polarize o disotd [Figure 7.174). The orientation
ths polrization (or dipole) is such hat the positive charge a he point ol PK) trans o Ls reduced
ad the wil be negative charge atthe point of PAU rans o L [Figure 7.17(0)]. Ths, is negative
age repel the ligand X. Hence he atraction ofX fr PAM is reduced and the Pt—X bond eran to Lis
tend and wekend The Pt ood rans toL becomes longer and longer than P(X bond sto
(Figure 721) because here is no polarization in wo X ligand which are tans to one another. The
ening o! PX bond runs to L She he replacement of X rans tL by the incoming ligand.
e ligand L which has the preter polarizability also as the greater rans eect.
RE
A al RM CR D AE
(2) The x-bonding Theory
‘The electrostatic polarization theory has explained the mans effect of the ligands which areo-donor
and ie atthe low end ofthe ran effect seres ke CI, Br“, 1, OH, #0, NH ec. But this theory
could nt explain the ron effect of ligands which are xacceptors ande tthe high end of rans effect
series ike CO, CN”,C2Ha, NO, PR et. The high anc effect of wazceptor ligands can be explained
on the basis of bonding theory.
"According to this theory the vacant or "oil ofthe meaccepor ligand (L) accept a pair of
nen mar it di i ryt ele tL soon ep det
dx bond) and also stabilizes he transition sae orintemediate,
Let us discuss the trons effect in rons1PLAzL (where L is the wbonding ligand) In mans
[PtA2LX complex an olefin (CH, forao-ondby donation fs clectrón deny to platinum, he.
ligands CO, CN formo bond by donation of pir of on-boadng electron fom carbon to platinum
and RyP forms o-bond by donation af a pair of electrons from phosphors to platinum,
When the ligand ike (CO, CN”, CzH4) fos end, there is donation of electron densi. om,
metal orbital of symmetry (say dy) into ligand (GayCaH, orbital of sane symmetry, he gan s*
ceba,
‘The withdrawal of electron density fo platinum increases the electron density toward the ligand
Land dimrishes in the direction of ligand X, Tus, the P-X bond is weakened and enteanc of an
incoming ligand (Y) becomes easy. This implies thatthe transition state (rigonl bipyramidal) is
scabilized andthe ate of substitution reactions enhanced. Tiss, of course, he effect of meta ligand
dx" bonding (Figure 720).
IfLis CO, then bondi formed by ration electron par tor d orbitals of PI) tothe vacant
xt of CO (Figure 7.18)
ILis RP, then bonds formed by donation felston pie rom orbitals of PU) tothe vacant
ital of phosphorus (Figur 7.19)
The strong raccepto ligand (L) occupies an equeorial positon inthe trigonal bipyramidal (TBP)
intemuedito and forces the ligand X o replace o form the square planar product.
The five coordinated trigonal bipyramidal intermediate is stabilized because there is a strong.
interaction of the filled -orbitals of PAI) wit the orbitals of equatorial ligands than with the axial
figands.
RB
PO
Figure 7,18 Med so ligan ranger of pi of electrons to form dx ® bond.
QM
GW?
gure 7.19 Moule lint doauion of cuz afeleston o for dr don.
der
sane, the vibrational frequency and coupling constant ans o ein a complex is called he rans
uence
Let us consider the following 5% ps of square planar complexes of PI) 0 understand this
peony
@ PeX a Type Complex: Acsordi bs theory the PAI) ction induces dipole in al the four
gands Since al the four igands(. ligands trons to one anther) ace same, therefoe, he induced
pole af one ligand is cancelled by he dipole ofits mans Hand and thus te resultant dipole is ze.
Figure 7.16) Hence none of the fou ligund hop trans eet
(0 1PELX 1] Type Complex : Te ray charge on Pr ion induces a diple in al the four
Iganés, The dipole in uo X ligands Which are sini and trans to each other balance each other Thus,
1 ofthese two ligands do aot show ras effet. Onthe ober hand, the two ligands L'an X which re
ras 6 each or do not because Lis larger and has greater polarizability than X. The et cest is that
primary charge on Pi indüces a dile in L which in tum induces dipole ia PI, Tn aer
or, can ey that Pi} and L bth becomes polarize o disotd [Figure 7.174). The orientation
ths polrization (or dipole) is such hat the positive charge a he point ol PK) trans o Ls reduced
ad the wil be negative charge atthe point of PAU rans o L [Figure 7.17(0)]. Ths, is negative
age repel the ligand X. Hence he atraction ofX fr PAM is reduced and the Pt—X bond eran to Lis
tend and wekend The Pt ood rans toL becomes longer and longer than P(X bond sto
(Figure 721) because here is no polarization in wo X ligand which are tans to one another. The
ening o! PX bond runs to L She he replacement of X rans tL by the incoming ligand.
e ligand L which has the preter polarizability also as the greater rans eect.
RE
A al RM CR D AE
(2) The x-bonding Theory
‘The electrostatic polarization theory has explained the mans effect of the ligands which areo-donor
and ie atthe low end ofthe ran effect seres ke CI, Br“, 1, OH, #0, NH ec. But this theory
could nt explain the ron effect of ligands which are xacceptors ande tthe high end of rans effect
series ike CO, CN”,C2Ha, NO, PR et. The high anc effect of wazceptor ligands can be explained
on the basis of bonding theory.
"According to this theory the vacant or "oil ofthe meaccepor ligand (L) accept a pair of
nen mar it di i ryt ele tL soon ep det
dx bond) and also stabilizes he transition sae orintemediate,
Let us discuss the trons effect in rons1PLAzL (where L is the wbonding ligand) In mans
[PtA2LX complex an olefin (CH, forao-ondby donation fs clectrón deny to platinum, he.
ligands CO, CN formo bond by donation of pir of on-boadng electron fom carbon to platinum
and RyP forms o-bond by donation af a pair of electrons from phosphors to platinum,
When the ligand ike (CO, CN”, CzH4) fos end, there is donation of electron densi. om,
metal orbital of symmetry (say dy) into ligand (GayCaH, orbital of sane symmetry, he gan s*
ceba,
‘The withdrawal of electron density fo platinum increases the electron density toward the ligand
Land dimrishes in the direction of ligand X, Tus, the P-X bond is weakened and enteanc of an
incoming ligand (Y) becomes easy. This implies thatthe transition state (rigonl bipyramidal) is
scabilized andthe ate of substitution reactions enhanced. Tiss, of course, he effect of meta ligand
dx" bonding (Figure 720).
IfLis CO, then bondi formed by ration electron par tor d orbitals of PI) tothe vacant
xt of CO (Figure 7.18)
ILis RP, then bonds formed by donation felston pie rom orbitals of PU) tothe vacant
ital of phosphorus (Figur 7.19)
The strong raccepto ligand (L) occupies an equeorial positon inthe trigonal bipyramidal (TBP)
intemuedito and forces the ligand X o replace o form the square planar product.
The five coordinated trigonal bipyramidal intermediate is stabilized because there is a strong.
interaction of the filled -orbitals of PAI) wit the orbitals of equatorial ligands than with the axial
figands.
RB
PO
Figure 7,18 Med so ligan ranger of pi of electrons to form dx ® bond.
QM
GW?
gure 7.19 Moule lint doauion of cuz afeleston o for dr don.
der
PIX bona eng increases
tooo decaso in leon des.
‘The ligands lying on high end in the rans effet series ace strong macceptros, followed by strong.
‘e-donors(c.,stong polarizabe) like SCN Tec. The ligands atte low end ofthe series are eier
strong o-donor nor acceptors but thas are song donar like H0, OH”, NH et.
Substitution recto in otha complexes proceed by the dissociative (Le, Sy) mechanism
because ar dissociation of oe group aon fan neo group does ot charge he coon
number. theeisnoincessein te Mitance dag the diseciative mechanism andthe sabi of
intermediate (CN. = 5) greater. teraction in otahdeal complexes woud osu by associative
mechanism (Le, Sy2 meds, he ber willbe increase in coo intin number (Le insease in
ance) which causes the deceso ia stability ofthe intermediate o activated complex of
‘The miceophilicsubstntion reactions in squar planar complexes proceed through associative
ie Sr?) mecharism bocase ee i mal sei and electronic epulsions andthe incoming and
attacks on Pl) easly o fom a stable goal bipyramidal intermediate o atvated complex In
nucleophite sbstntion reaction in square paar complexes of PU) te incoming ligand Y attacks
fom eter side of the plane (above or below ofthe plane of molecale) o foma five oats
intermediate Furthermore inthe squat planar complex, Pu) has a vacant p, orbital ofthereavly
low energy which accepts the electron pir donated bythe incoming ligand and a squat pyramidal
species is formed (Figure 7.22) which in tum undergoes a transformation to a tigeal bipyramidal
intermediate
‘The TBP species that forms during the reaction and then rearrangesto give product may exit eter
as an Intermediate oc an activate complex In TBP species the ligands L, X and Y lie on is equatorial
poston and the two ands A ions axial postions (Figure 7.22).
As X moves frm trigonal plane, the L-P-Y angle opens and the geometry is passed trough a
square pyramid to oa the square planar product.
It is observed that cis(PtAZLX] gives ei-produet and cans{PtAzLX] gives tran-product, Le,
these reactions are eniely steiowpecifc. This steiospecificity supports he reactions to proceed by
associative mechanism (Figure 223),
A
f i i
E aX 4
AE ESE
A Tre mechunisn of baii cis of gar plage complex [PAS wi Y” aqueos
Scltion to give PtAYY]” is on complicated by the occurarico of aleve pathways beonse
solvent water itself behaves as potential ligand. If the following reaction +
rra rg 0
is firstorder in complex and independent of the concentration of Y” then te cate of reacio rl be
equa toky(PtA;X"* Jendiffhereisanaltemative pathway in which the rte aw is overall second onder,
fist order in complex and first onlerinY” hen the rate of reaction will be ka PLA; X"*] Y”). both
reaction pathways oocur simultsmeously at comparable rats, the rate law wil be given by the
expression
Rate = h{PIA3K" Jako (PASX" HEY]
Et HPA]
tooo decaso in leon des.
‘The ligands lying on high end in the rans effet series ace strong macceptros, followed by strong.
‘e-donors(c.,stong polarizabe) like SCN Tec. The ligands atte low end ofthe series are eier
strong o-donor nor acceptors but thas are song donar like H0, OH”, NH et.
Substitution recto in otha complexes proceed by the dissociative (Le, Sy) mechanism
because ar dissociation of oe group aon fan neo group does ot charge he coon
number. theeisnoincessein te Mitance dag the diseciative mechanism andthe sabi of
intermediate (CN. = 5) greater. teraction in otahdeal complexes woud osu by associative
mechanism (Le, Sy2 meds, he ber willbe increase in coo intin number (Le insease in
ance) which causes the deceso ia stability ofthe intermediate o activated complex of
‘The miceophilicsubstntion reactions in squar planar complexes proceed through associative
ie Sr?) mecharism bocase ee i mal sei and electronic epulsions andthe incoming and
attacks on Pl) easly o fom a stable goal bipyramidal intermediate o atvated complex In
nucleophite sbstntion reaction in square paar complexes of PU) te incoming ligand Y attacks
fom eter side of the plane (above or below ofthe plane of molecale) o foma five oats
intermediate Furthermore inthe squat planar complex, Pu) has a vacant p, orbital ofthereavly
low energy which accepts the electron pir donated bythe incoming ligand and a squat pyramidal
species is formed (Figure 7.22) which in tum undergoes a transformation to a tigeal bipyramidal
intermediate
‘The TBP species that forms during the reaction and then rearrangesto give product may exit eter
as an Intermediate oc an activate complex In TBP species the ligands L, X and Y lie on is equatorial
poston and the two ands A ions axial postions (Figure 7.22).
As X moves frm trigonal plane, the L-P-Y angle opens and the geometry is passed trough a
square pyramid to oa the square planar product.
It is observed that cis(PtAZLX] gives ei-produet and cans{PtAzLX] gives tran-product, Le,
these reactions are eniely steiowpecifc. This steiospecificity supports he reactions to proceed by
associative mechanism (Figure 223),
A
f i i
E aX 4
AE ESE
A Tre mechunisn of baii cis of gar plage complex [PAS wi Y” aqueos
Scltion to give PtAYY]” is on complicated by the occurarico of aleve pathways beonse
solvent water itself behaves as potential ligand. If the following reaction +
rra rg 0
is firstorder in complex and independent of the concentration of Y” then te cate of reacio rl be
equa toky(PtA;X"* Jendiffhereisanaltemative pathway in which the rte aw is overall second onder,
fist order in complex and first onlerinY” hen the rate of reaction will be ka PLA; X"*] Y”). both
reaction pathways oocur simultsmeously at comparable rats, the rate law wil be given by the
expression
Rate = h{PIA3K" Jako (PASX" HEY]
Et HPA]
whereby and ar the fist oder and second order rate constants respectively. Experimental
evidence indicate tht this type o reactions are pseudo fra order, when Y isin large exces, ‘Thus,
the observed pseudo frst orde ate constant is related to ky and hy a Ñ
Kon hi the 7]
Since Y is in large excess, therefore, the concentration of Y~ is take tobe costa, Under this
condition he observed rate constant, Fy is pseudo first onder andis and ky assho
ec ot os related to, and asshown by the
CPE) i)
‘Equation (i indicate that by repeating the reaction at various concentrtions of V=, he values of
both and kz canbe obtained because a plot of ka against [Y” gives a sight ie with k as the
intercept ad asthe slope (Figure 7.24).
“
as
» +
2
gt —
2
1
‘The two ph of he reaction () are shown in Figure 725.
A
f ! t
x x *
ane ana “Say
| Nom 1 CE
A A A
ao ano
A
1
AX
|
A
tow ev
i t
x
Ant” ant
LE me |
A A
“The uper pth isthe solvent path and the lower one is rc path, he solvent path the solvent
(G,0)repheesX° ina slow rte whichis subsequently replaced by he esgentY ina rai step Ithas
been observed Y” dependent path is not an rocessbut ia diet y2pmcess and a second
coder path On the other hand the solvent path i a pseudo fist oder.
The ate constan du t slow displacement of X” by the solvent (H,O)and k is due tothe
dirt clopii displacement of X by Y”. Thus itis convenient to represent the solvent path kı as
Ze and be engen path as ky. Therefore, the ao (i echas
Koa = es PAY" di
EIN FAVOUR OF | TAT!
‘Mannan bis students have shown thatthe rates of hyrolyis ofthe series of complex a [PrCla 1?"
through (PUNA) CIJ are approximately same, although there is a three unit change in charge (i.¢.,—2
to +1) on the PH(T) complex.
Tae breaking of CI bond becomes mor dicl a e charge an ti complexes becomes more
positive Bt on te oir an, the formation of new bond (¿e atraco Px) fr incoming ligend)
increases in the sme onde. This supgests that inthe tarso sat both bod making and bond
Breaking is comparable impartan, Ths, he solvent path, e rec placent path kr
appears abe socitive (Sy) proces.
evidence indicate tht this type o reactions are pseudo fra order, when Y isin large exces, ‘Thus,
the observed pseudo frst orde ate constant is related to ky and hy a Ñ
Kon hi the 7]
Since Y is in large excess, therefore, the concentration of Y~ is take tobe costa, Under this
condition he observed rate constant, Fy is pseudo first onder andis and ky assho
ec ot os related to, and asshown by the
CPE) i)
‘Equation (i indicate that by repeating the reaction at various concentrtions of V=, he values of
both and kz canbe obtained because a plot of ka against [Y” gives a sight ie with k as the
intercept ad asthe slope (Figure 7.24).
“
as
» +
2
gt —
2
1
‘The two ph of he reaction () are shown in Figure 725.
A
f ! t
x x *
ane ana “Say
| Nom 1 CE
A A A
ao ano
A
1
AX
|
A
tow ev
i t
x
Ant” ant
LE me |
A A
“The uper pth isthe solvent path and the lower one is rc path, he solvent path the solvent
(G,0)repheesX° ina slow rte whichis subsequently replaced by he esgentY ina rai step Ithas
been observed Y” dependent path is not an rocessbut ia diet y2pmcess and a second
coder path On the other hand the solvent path i a pseudo fist oder.
The ate constan du t slow displacement of X” by the solvent (H,O)and k is due tothe
dirt clopii displacement of X by Y”. Thus itis convenient to represent the solvent path kı as
Ze and be engen path as ky. Therefore, the ao (i echas
Koa = es PAY" di
EIN FAVOUR OF | TAT!
‘Mannan bis students have shown thatthe rates of hyrolyis ofthe series of complex a [PrCla 1?"
through (PUNA) CIJ are approximately same, although there is a three unit change in charge (i.¢.,—2
to +1) on the PH(T) complex.
Tae breaking of CI bond becomes mor dicl a e charge an ti complexes becomes more
positive Bt on te oir an, the formation of new bond (¿e atraco Px) fr incoming ligend)
increases in the sme onde. This supgests that inthe tarso sat both bod making and bond
Breaking is comparable impartan, Ths, he solvent path, e rec placent path kr
appears abe socitive (Sy) proces.
nin aeons iter nother que pla ber wee ome cnica!
cheng te rio as of he tale esmas, Da a en al
compl Yo mothe, Elecron taser ji of Santon teal ls nn ae
ln tdaion on) sons wich ole he ar ls in conn
Saar, The len waster easton may ovat ete wi le onions
Top ses deen, te extn so ml raso iso xine
sali compli called reducing gem On the ter hn te conte whch eae chee a
Orion to metal das sn iS tbe eel a oop eh ea
‘get Aneanpl on een tant easton en
Leen} HIRSCH" — E +
coa RN HAC
In this reaction (Fe(CN)g]* is oxidined by [FE(CN)e]” and (Fe(CN)G is reduced by
Fey“,
The leo wanfer reactions involving transition m lex re believed to occur by the
following two mechanisms dis zn Br
{D Outer Sphere Mechanism
A mer Sphere Mechanism
(9 Outer Sphere Mechanism
soils oe eee nn
Sra en
Suey eter
Soir maa ese ema
An ste prison vase may car ine aligner po
ln e fi sept udn an foi oe cen ma psa Sl
Ox Rel =o Oxf Rod
se Pre at
dere ac ofthe eto ona u ls organico de
‘solvent molecules and changes in M-L bood lengths which occurs before electron n
“electron transfer takes place. un “ mine
Or Red “OxfRet
In al sp, on pi iii
Oxf} Red* == Ox +Red*
Salient Features of Outer Sphere Mechanism,
10) Both the reactants (ke, oxidant and educan) sould be kinetically inet. However, ¡Pone ofthe
amples is labile, the the inet comple should not poses a don tom which canbe used to
fom the bride wth able complex. 3
For example : Reduction of {Fe(CN)¢]* by{Cr(Fg0)6}*.
Arbo the oxidant andthe eductatare bile and there possiblity ofeletron transfer from x*
of reducant othe x* of oxidant, then th restion proceeds tough outer sphere mechanism.
For example: (Fe(HigO)¢]** + (Fe(H20}5}°* — (FAM O) 6" + [Fe(H1:0)6}"*
(2) When both the reactants are inert with respect to ligand exchange e.g., [Fe (EN)6]*” and
LFeCN)6P a close approach of the metal ions is impossible and the electron transfer takes place
‘bya mmneling or outer sphere mechanism. The te of eleton sfr depends upon the ability of
“électrons to tunnel through the ligands.
(©) Therate constants of electron transfer by outer sphere mechan are found to vary over a wide
ages shown inthe Table 75 and 76
Accoring 0 Frank-Condon principle, the electronic tans accar much more rapily than
‘eaangement of ato so that bond distances d co change during very short me of electronic
tension
‘The electron transfer is very fast when both the complexes are low spa including that the electron
Anse ake place for g(a") of reducto the fg) of oxidant. The fist reason is that
ci levels of these twos, bias ae sae The a mas ar o shielded from he gan
andthe leon transfer rom ant is easier nd no inp reg required, The second reason is
that teri o appreciable change in NC bond eng docto" x" electron transfer
‘Thezatezof electron transfer are much fer betwee the completes whch have naccepor ligands
{ike CN phen, py et) han for complexes fl same metal baviagpuely.-donorigands (like
#20, NE3,en etc). The wacceptor ligands have vacant x” orbitals that can accept clectron being|
transferred, then pass them on to the receiving metal jon (¿+e., oxidant) whereas theo-donor ligands |
onot ave such tendency. Ths, outer sphere electron mars et lern transfer fom one
‘meal to anotherincas of complexes having vn ligands. On be oe hand, electo trans
indi, fom one metal o ligando 0 the anther eta) i the complexes have maceta
lias.
‘The election transfer is slow if electron transfer occurs from ey (oro orbital of reductant to eg
6x0" jottioxidant because thee orbits ar shell om he sumoundings (e, igands) and
canse of con i steely slow. The 9 = y lon transfer ste than > eg
tante
lern tanser between eh spi and low pin complees sas slow because lern tans
ar aa
beoxidantresultinginIaíge changes in M-L bond length. This conditions arses between high spin |
Co} (d* Yan tow spin Co** (a) complexes.
cheng te rio as of he tale esmas, Da a en al
compl Yo mothe, Elecron taser ji of Santon teal ls nn ae
ln tdaion on) sons wich ole he ar ls in conn
Saar, The len waster easton may ovat ete wi le onions
Top ses deen, te extn so ml raso iso xine
sali compli called reducing gem On the ter hn te conte whch eae chee a
Orion to metal das sn iS tbe eel a oop eh ea
‘get Aneanpl on een tant easton en
Leen} HIRSCH" — E +
coa RN HAC
In this reaction (Fe(CN)g]* is oxidined by [FE(CN)e]” and (Fe(CN)G is reduced by
Fey“,
The leo wanfer reactions involving transition m lex re believed to occur by the
following two mechanisms dis zn Br
{D Outer Sphere Mechanism
A mer Sphere Mechanism
(9 Outer Sphere Mechanism
soils oe eee nn
Sra en
Suey eter
Soir maa ese ema
An ste prison vase may car ine aligner po
ln e fi sept udn an foi oe cen ma psa Sl
Ox Rel =o Oxf Rod
se Pre at
dere ac ofthe eto ona u ls organico de
‘solvent molecules and changes in M-L bood lengths which occurs before electron n
“electron transfer takes place. un “ mine
Or Red “OxfRet
In al sp, on pi iii
Oxf} Red* == Ox +Red*
Salient Features of Outer Sphere Mechanism,
10) Both the reactants (ke, oxidant and educan) sould be kinetically inet. However, ¡Pone ofthe
amples is labile, the the inet comple should not poses a don tom which canbe used to
fom the bride wth able complex. 3
For example : Reduction of {Fe(CN)¢]* by{Cr(Fg0)6}*.
Arbo the oxidant andthe eductatare bile and there possiblity ofeletron transfer from x*
of reducant othe x* of oxidant, then th restion proceeds tough outer sphere mechanism.
For example: (Fe(HigO)¢]** + (Fe(H20}5}°* — (FAM O) 6" + [Fe(H1:0)6}"*
(2) When both the reactants are inert with respect to ligand exchange e.g., [Fe (EN)6]*” and
LFeCN)6P a close approach of the metal ions is impossible and the electron transfer takes place
‘bya mmneling or outer sphere mechanism. The te of eleton sfr depends upon the ability of
“électrons to tunnel through the ligands.
(©) Therate constants of electron transfer by outer sphere mechan are found to vary over a wide
ages shown inthe Table 75 and 76
Accoring 0 Frank-Condon principle, the electronic tans accar much more rapily than
‘eaangement of ato so that bond distances d co change during very short me of electronic
tension
‘The electron transfer is very fast when both the complexes are low spa including that the electron
Anse ake place for g(a") of reducto the fg) of oxidant. The fist reason is that
ci levels of these twos, bias ae sae The a mas ar o shielded from he gan
andthe leon transfer rom ant is easier nd no inp reg required, The second reason is
that teri o appreciable change in NC bond eng docto" x" electron transfer
‘Thezatezof electron transfer are much fer betwee the completes whch have naccepor ligands
{ike CN phen, py et) han for complexes fl same metal baviagpuely.-donorigands (like
#20, NE3,en etc). The wacceptor ligands have vacant x” orbitals that can accept clectron being|
transferred, then pass them on to the receiving metal jon (¿+e., oxidant) whereas theo-donor ligands |
onot ave such tendency. Ths, outer sphere electron mars et lern transfer fom one
‘meal to anotherincas of complexes having vn ligands. On be oe hand, electo trans
indi, fom one metal o ligando 0 the anther eta) i the complexes have maceta
lias.
‘The election transfer is slow if electron transfer occurs from ey (oro orbital of reductant to eg
6x0" jottioxidant because thee orbits ar shell om he sumoundings (e, igands) and
canse of con i steely slow. The 9 = y lon transfer ste than > eg
tante
lern tanser between eh spi and low pin complees sas slow because lern tans
ar aa
beoxidantresultinginIaíge changes in M-L bond length. This conditions arses between high spin |
Co} (d* Yan tow spin Co** (a) complexes.
4) Outer sphere electron transfer reactions between complexes of different meta cations i, cross
reactions are fate than that of self exchange reactions.
(5) Electron transfer oscuring between the complexes of same metal cations are called self exchange
reactions. In self exchange reactions no net chemical reaction actually occurs because the products
‘ace indistinguishable from the estan. Various se exchange reactions are shown in Table 7.5. On
‘the other hand, the electron transfer occuring between he complexes of different metal cations are
called cross reactions In cross reactions nt chemical reaction occur.
ND ANG — Mel «CG
a (ctf exchange reaction)
[Re(CN oI + MH" — IF)” + [MEN]
D Rs nn Pe
LEI" FS” PEN + Fa
) In outer sphere mechanism, the spin forbidden reaction ar slow because these reactions require
“more activation energy.
‘The auter sphere mechanisms ilustrtd below by taking various examples:
(a) [Fe(CN)< J + CNP > FeCN)s + Feeney
Lori Low sin
Ga Ga)
Inet, last
Fe —CN™ Fer ar
Bond length = 195 pm Bond length = 192 pm
‘The ate of electron transfer is Ast or ih following reasons:
(6) Both the complexes [Fe{CN)g]" "and {Fe(CN)6 at inet and election transfer is faster
han jade exigir crecen
{i Elton transfer spin allowed.
ii) The electron transfer occurs from 124 of (FE(CN)gI to fag of [Fe(CN)g]*> complex. The
tg obi pt even chat nen engen e-CN ot Tel
electron transfer becomes easy. © —_— -
(Gv) Since tag orbitals point between the ligands, therefore, M-L distance do not change
appreciably.
(9) The ligand CN“ is unsaturated and a eacoeptor which facilitates the electron tunneling Also
since the CN” ligand is a eacceporit, erre, stabilizes complexes in lower ox te
by formation of back z bonding, cones or ont
A ON
ns PS
Ga) dé)
Laie Labi
Fe} OH Fe OH)
Bondiengh=78 pm Bord eng pm
Intisreacion, the reactants and product arth same ence the position of ado active abel. The
energy of activation for this reaction is 32 KI mol which indicates thatthe cate of electron trans is
slow (second order rate constant Ky = 4L at's),
According to Frank Condon principle, lern ante takes place whea the energy levels ofthe
participating orbitals are same andthe elect enter takes place much moro rapidly than the change in
position of noe. Ths, during electron transfer M-L bond lengths remain unchanged
In this reaction an electron is rasfened fom ng OFF) 10 gf F(t). The Fe?" OH and
Fe} OH} bond lengths are 92 pm and 8 pm espetively, Le, Fe** — OH bond eng 14 im
‘smaller than thatof Fe2* OH}, This indicate bat th era levels ofthe orbitals are not equal. Since
the Fe-O bord eng does ot change during ie electron transfer his transfer electron wth outa
input of energy will produce [Fe(H;0)]*, with Fe-O bond similar to Fe-O bond in| [Fe
and the [Fe(Hy0)g]?" with Fe-O bond similar to [Fe(H20)6]°". These two products are in
brtionally excited sae. Bo the products will lease energy inthe for of heat by vibrating to each
the equlibium bond length. I seems that energy is created but iti the violation ofthe ist a of
thermeriyoamics. Consequenty, an enough vibrational activation energy has been provided to each
‘ample on to bring them to the same energy levels ad then transfer of electron to takes place.
“Consequenty, the electron transfers most probable when an activation energy hs been given to
ack complex ion. The activation energy cases the shorteing ofthe bonds in (Fe(H0}eI" and
Tengtbening ofthe bonds in (Fe(t0)<)* wail he arcipating orbitals are of te same energy. In
case of self exchange reaction, the Fe-O bond lengús have reached the same intermediate vale. For
‘os reaction, the ML bond legs do not become same values but the orbital energy maybe
© Co) + (CON) — CNP + (CoO) EI
Low pin rin
Ge) Ga
Inet Labio
Co- Nit Co-Nis
Bond length = 1935 pm Bond eng 2114 pm
“The rae of ecto transfer for is rections dow (second order at constant =10 $ Lots")
because ofthe following feasons:
reactions are fate than that of self exchange reactions.
(5) Electron transfer oscuring between the complexes of same metal cations are called self exchange
reactions. In self exchange reactions no net chemical reaction actually occurs because the products
‘ace indistinguishable from the estan. Various se exchange reactions are shown in Table 7.5. On
‘the other hand, the electron transfer occuring between he complexes of different metal cations are
called cross reactions In cross reactions nt chemical reaction occur.
ND ANG — Mel «CG
a (ctf exchange reaction)
[Re(CN oI + MH" — IF)” + [MEN]
D Rs nn Pe
LEI" FS” PEN + Fa
) In outer sphere mechanism, the spin forbidden reaction ar slow because these reactions require
“more activation energy.
‘The auter sphere mechanisms ilustrtd below by taking various examples:
(a) [Fe(CN)< J + CNP > FeCN)s + Feeney
Lori Low sin
Ga Ga)
Inet, last
Fe —CN™ Fer ar
Bond length = 195 pm Bond length = 192 pm
‘The ate of electron transfer is Ast or ih following reasons:
(6) Both the complexes [Fe{CN)g]" "and {Fe(CN)6 at inet and election transfer is faster
han jade exigir crecen
{i Elton transfer spin allowed.
ii) The electron transfer occurs from 124 of (FE(CN)gI to fag of [Fe(CN)g]*> complex. The
tg obi pt even chat nen engen e-CN ot Tel
electron transfer becomes easy. © —_— -
(Gv) Since tag orbitals point between the ligands, therefore, M-L distance do not change
appreciably.
(9) The ligand CN“ is unsaturated and a eacoeptor which facilitates the electron tunneling Also
since the CN” ligand is a eacceporit, erre, stabilizes complexes in lower ox te
by formation of back z bonding, cones or ont
A ON
ns PS
Ga) dé)
Laie Labi
Fe} OH Fe OH)
Bondiengh=78 pm Bord eng pm
Intisreacion, the reactants and product arth same ence the position of ado active abel. The
energy of activation for this reaction is 32 KI mol which indicates thatthe cate of electron trans is
slow (second order rate constant Ky = 4L at's),
According to Frank Condon principle, lern ante takes place whea the energy levels ofthe
participating orbitals are same andthe elect enter takes place much moro rapidly than the change in
position of noe. Ths, during electron transfer M-L bond lengths remain unchanged
In this reaction an electron is rasfened fom ng OFF) 10 gf F(t). The Fe?" OH and
Fe} OH} bond lengths are 92 pm and 8 pm espetively, Le, Fe** — OH bond eng 14 im
‘smaller than thatof Fe2* OH}, This indicate bat th era levels ofthe orbitals are not equal. Since
the Fe-O bord eng does ot change during ie electron transfer his transfer electron wth outa
input of energy will produce [Fe(H;0)]*, with Fe-O bond similar to Fe-O bond in| [Fe
and the [Fe(Hy0)g]?" with Fe-O bond similar to [Fe(H20)6]°". These two products are in
brtionally excited sae. Bo the products will lease energy inthe for of heat by vibrating to each
the equlibium bond length. I seems that energy is created but iti the violation ofthe ist a of
thermeriyoamics. Consequenty, an enough vibrational activation energy has been provided to each
‘ample on to bring them to the same energy levels ad then transfer of electron to takes place.
“Consequenty, the electron transfers most probable when an activation energy hs been given to
ack complex ion. The activation energy cases the shorteing ofthe bonds in (Fe(H0}eI" and
Tengtbening ofthe bonds in (Fe(t0)<)* wail he arcipating orbitals are of te same energy. In
case of self exchange reaction, the Fe-O bond lengús have reached the same intermediate vale. For
‘os reaction, the ML bond legs do not become same values but the orbital energy maybe
© Co) + (CON) — CNP + (CoO) EI
Low pin rin
Ge) Ga
Inet Labio
Co- Nit Co-Nis
Bond length = 1935 pm Bond eng 2114 pm
“The rae of ecto transfer for is rections dow (second order at constant =10 $ Lots")
because ofthe following feasons:
© (CoQNHs)6P* is low spin (4,2) and (Co(NHs )g]”™* is high spin (4,8). Low spin
{CoONHs)6]* has an electronic configuration 435
ai the met detects pong in
between the ligands, On the other hand, the high spin LOCH)?" has’ an electronic
configuro, vivo y econ pining dire atthe ins Th cons psa
y als cae more mabo wi el
ds tan to ecos Terie Oo" Ni
‘bond distance is larger han that of Co NHI . The Co?* NH bond distance is1956pm and
te CO?" = Neston dsaneis2,d pa In case ML bon lens re diet eng nd
ene activation ear ls nsdd ma them he ame ne anti it
Since Co (I) and Co( complexes are high spin and low spin respectively. No simple edition or
removal of an elctron can convert these configuration into one another. Therefore, it necessary to
excite he oxidation sates before the reaction can occur as shown below:
CoG ts Blane $ a OF
co eget) et Tension Meg 0 Co
‘The electoic ground and excite states can lso be win a follows
co? anor? _ mas Sn (nt co
Co (664) = A a Tage? CoP
Es (cont) (ciel) es
[the ligands re aranged in increasing order of crystal field spifting OX< Hz0< EDTA< Mi
< en < phen <ON™, transfer of electron from Co (I) to Co) is faster either atthe weak end oc the
strong end but slow in the middle. Therefore, for example, Electron transfer from [CO(HaO)EJ" 10
{Co(H,0)6]** is faster. 0 isa weak ligand and A. for low spin (Co(H1¿0)6]”* à not very high
‘Thus {Co(H>0)6]°* can be as excited to para magnetic [Co(H20)6]* by input of small ener.
(Co(iig0}e* — {Co(H0)¢ 2°
«ay Ge
A aa
Diamagneo —— Paramagnete
(Gromdsa) Excited state)
Since [Co(H30)4]°* is high pin and A, i alo viry small. Thus, (Co(1¿0)e] cam also be
excites easy
Too)" == [Colt O)"
[E97 (Se)
a eon ae
Growdsme cited iat
Nowhere it "(org to elesron transfer from (Co(H,0)63 inexcited state toexcted
[Co(H120)6]”* „The products so obtained ae in excited states.
LOT, COMO)" [CORE [Ont Ope
GD CA] ee * ob
cited sate Exciedgate ‘Excited site ited state
aly te exited product goto the round ste. à
Lao), (ONF a ICO {Col 0)"
(Gy) Ge) he) Go)
Exciedsate Frida Ground sate Ground state
Rate of electron transfer from [Co(pben}3 )?* to {Co(phen)33°* is faster au wes
pe 1H )6]”". Since phenantbroline is a strong ligand, therefore, high spin
Co rd
‘her ancestro efecto as Ñ
Tt is concluded that the rate of electron transfer [Co(NH3)61%* - 1Co(NH1)6"" and
{Cofen)s {Cote systems is slower than ahat of [Co(HzO)6}* —{ColHO)e)* and
[Co(phen)3** ~{Cofphen)s}** systems Second order rate constants for electron transfer for various
o (1 Co (UD stes som in Tb 75 ad 7.60 support tis conclusion
‘The rate of electron transfer is rapid between ACOFS IS" —(CoFe]”” system. Both te Reaver’
(cay ano)” ae ih pi comple with he lern onion nl
= etc Toe, con nag [Co] ay CORE)” cases wih
int of litle een: Ts, te of eon teneis as. u o
“The rate of electron transfer between [Co(diars)3 1 * (Coldiara)s D is es where dias =
o-phenyene bs diet aso. The complexs{Co(siars)s}* and{Co(ias) ax lv sini
Soon cota (ede peca he ow pin Cr) wi ee
configuro ete avin ene tovars low spin) eaniguaton.Threlo e
aro electo cant sa
esa, ng) tec tte ts place very rap hen thes sd of
en eier ei lowing electron raster to takes place (see Tal 75) comida
an clon tanfer between (Ru (NH) and [Ru CNE Je".
{CoONHs)6]* has an electronic configuration 435
ai the met detects pong in
between the ligands, On the other hand, the high spin LOCH)?" has’ an electronic
configuro, vivo y econ pining dire atthe ins Th cons psa
y als cae more mabo wi el
ds tan to ecos Terie Oo" Ni
‘bond distance is larger han that of Co NHI . The Co?* NH bond distance is1956pm and
te CO?" = Neston dsaneis2,d pa In case ML bon lens re diet eng nd
ene activation ear ls nsdd ma them he ame ne anti it
Since Co (I) and Co( complexes are high spin and low spin respectively. No simple edition or
removal of an elctron can convert these configuration into one another. Therefore, it necessary to
excite he oxidation sates before the reaction can occur as shown below:
CoG ts Blane $ a OF
co eget) et Tension Meg 0 Co
‘The electoic ground and excite states can lso be win a follows
co? anor? _ mas Sn (nt co
Co (664) = A a Tage? CoP
Es (cont) (ciel) es
[the ligands re aranged in increasing order of crystal field spifting OX< Hz0< EDTA< Mi
< en < phen <ON™, transfer of electron from Co (I) to Co) is faster either atthe weak end oc the
strong end but slow in the middle. Therefore, for example, Electron transfer from [CO(HaO)EJ" 10
{Co(H,0)6]** is faster. 0 isa weak ligand and A. for low spin (Co(H1¿0)6]”* à not very high
‘Thus {Co(H>0)6]°* can be as excited to para magnetic [Co(H20)6]* by input of small ener.
(Co(iig0}e* — {Co(H0)¢ 2°
«ay Ge
A aa
Diamagneo —— Paramagnete
(Gromdsa) Excited state)
Since [Co(H30)4]°* is high pin and A, i alo viry small. Thus, (Co(1¿0)e] cam also be
excites easy
Too)" == [Colt O)"
[E97 (Se)
a eon ae
Growdsme cited iat
Nowhere it "(org to elesron transfer from (Co(H,0)63 inexcited state toexcted
[Co(H120)6]”* „The products so obtained ae in excited states.
LOT, COMO)" [CORE [Ont Ope
GD CA] ee * ob
cited sate Exciedgate ‘Excited site ited state
aly te exited product goto the round ste. à
Lao), (ONF a ICO {Col 0)"
(Gy) Ge) he) Go)
Exciedsate Frida Ground sate Ground state
Rate of electron transfer from [Co(pben}3 )?* to {Co(phen)33°* is faster au wes
pe 1H )6]”". Since phenantbroline is a strong ligand, therefore, high spin
Co rd
‘her ancestro efecto as Ñ
Tt is concluded that the rate of electron transfer [Co(NH3)61%* - 1Co(NH1)6"" and
{Cofen)s {Cote systems is slower than ahat of [Co(HzO)6}* —{ColHO)e)* and
[Co(phen)3** ~{Cofphen)s}** systems Second order rate constants for electron transfer for various
o (1 Co (UD stes som in Tb 75 ad 7.60 support tis conclusion
‘The rate of electron transfer is rapid between ACOFS IS" —(CoFe]”” system. Both te Reaver’
(cay ano)” ae ih pi comple with he lern onion nl
= etc Toe, con nag [Co] ay CORE)” cases wih
int of litle een: Ts, te of eon teneis as. u o
“The rate of electron transfer between [Co(diars)3 1 * (Coldiara)s D is es where dias =
o-phenyene bs diet aso. The complexs{Co(siars)s}* and{Co(ias) ax lv sini
Soon cota (ede peca he ow pin Cr) wi ee
configuro ete avin ene tovars low spin) eaniguaton.Threlo e
aro electo cant sa
esa, ng) tec tte ts place very rap hen thes sd of
en eier ei lowing electron raster to takes place (see Tal 75) comida
an clon tanfer between (Ru (NH) and [Ru CNE Je".
DEE
PU RE (RAGE) + Ro
Low sin Low spin
5 tae
Ge) NT
DOCS DONS
Int ten
Ru? NH Ru?" NH;
Bord length = 210.4 pm Bond length = 2144 pm
Rate of leon transfer rom [Ru (NH }g]"* to [Ru (NHs)63*" is rapid because:
Différence in M-L bond fength in Ru (It) and Ru (Uf complexes is small (Le, pm).
i) Electron transfer takes place from x* of[Ru (NH }g}"* to x* of [Ru (NH }}** withoutany
input oc a litle input of energy.
Mode of electron transfer and rate constants for some outer sphere reactions is given in Table 77.
‘The cate of electron transfer between [Ru (phen); ?* and [Ru (phen); 1 * or [Ru (CN) ]*" and
{Ru(CN)¢}?" is more rapid than the eléctron transfer between (Ru(NH3)6]?" and [Ru(NH 6
basse CN andpen ligands ace acceptor nd natural which ciliates the wanser of
electron through tunnel,
Table 7.5 Second Order Rate Constants for Various Outer Self Exchange
‘Sphere Electron Transfer Reactions at 25°C
COS 74x10°
[Feten PY + Feten) }* 23x10?
ep "elEco 1 >106
DOTE 210
TRUE JG ro x10?
cur a w
LOSC os 210%
Late) (Ro ptes), Pe 2107
LRO) (BHO 4
COP" + (CO) -5
(Coen "+ (Cohen) 40
(ot ef + (Cat <10?
(Caen P* + (Coens 14x10*
TOR TO saxo
OS OS 10?
‘Table 78 Second Order Rate Constants for Some Outer Sphere Gross Reactions at 25°C
FAC «(ul 3.8x10°
(tte LS 2 10x10
[ction P* ta" 34x10
ACHULO)F* + (CAP P* 3
LRO" RD 12x10?
LOUP HC re" 2x10?
[VARO Ho" 2104
(vO. «(Cora 38x10?
VOOR) D 80
LPC + (Fe(Phead P* 10
[er O)sP* RALON 2x10"
[En 6605 > = slot
LFGLOÏ + (FC 58x10°
Cross Reactions
Electron transfer reaction between completely different eomplexes ae called ross reactions. In
these reactions there i a net chemical change and the rate of electron transfer is faster than the
comesponding self exchange reactions (Table 7.6) in pie of en otherwise lage activation energy
(ransfriavolving atleast one e electon). The large amouat of activation enemy is encountered by the
change in fee energy and asa result there is a net decrease in fie energy. More the decrease in fice
energy, faster vil e he rte of electron taser
“The decrease in five energy during electron transfer indicate hat he energy of eactants is preter
than that ofthe products and the free energy profile isnot spmmeiie (ee figure 726)
PU RE (RAGE) + Ro
Low sin Low spin
5 tae
Ge) NT
DOCS DONS
Int ten
Ru? NH Ru?" NH;
Bord length = 210.4 pm Bond length = 2144 pm
Rate of leon transfer rom [Ru (NH }g]"* to [Ru (NHs)63*" is rapid because:
Différence in M-L bond fength in Ru (It) and Ru (Uf complexes is small (Le, pm).
i) Electron transfer takes place from x* of[Ru (NH }g}"* to x* of [Ru (NH }}** withoutany
input oc a litle input of energy.
Mode of electron transfer and rate constants for some outer sphere reactions is given in Table 77.
‘The cate of electron transfer between [Ru (phen); ?* and [Ru (phen); 1 * or [Ru (CN) ]*" and
{Ru(CN)¢}?" is more rapid than the eléctron transfer between (Ru(NH3)6]?" and [Ru(NH 6
basse CN andpen ligands ace acceptor nd natural which ciliates the wanser of
electron through tunnel,
Table 7.5 Second Order Rate Constants for Various Outer Self Exchange
‘Sphere Electron Transfer Reactions at 25°C
COS 74x10°
[Feten PY + Feten) }* 23x10?
ep "elEco 1 >106
DOTE 210
TRUE JG ro x10?
cur a w
LOSC os 210%
Late) (Ro ptes), Pe 2107
LRO) (BHO 4
COP" + (CO) -5
(Coen "+ (Cohen) 40
(ot ef + (Cat <10?
(Caen P* + (Coens 14x10*
TOR TO saxo
OS OS 10?
‘Table 78 Second Order Rate Constants for Some Outer Sphere Gross Reactions at 25°C
FAC «(ul 3.8x10°
(tte LS 2 10x10
[ction P* ta" 34x10
ACHULO)F* + (CAP P* 3
LRO" RD 12x10?
LOUP HC re" 2x10?
[VARO Ho" 2104
(vO. «(Cora 38x10?
VOOR) D 80
LPC + (Fe(Phead P* 10
[er O)sP* RALON 2x10"
[En 6605 > = slot
LFGLOÏ + (FC 58x10°
Cross Reactions
Electron transfer reaction between completely different eomplexes ae called ross reactions. In
these reactions there i a net chemical change and the rate of electron transfer is faster than the
comesponding self exchange reactions (Table 7.6) in pie of en otherwise lage activation energy
(ransfriavolving atleast one e electon). The large amouat of activation enemy is encountered by the
change in fee energy and asa result there is a net decrease in fie energy. More the decrease in fice
energy, faster vil e he rte of electron taser
“The decrease in five energy during electron transfer indicate hat he energy of eactants is preter
than that ofthe products and the free energy profile isnot spmmeiie (ee figure 726)
RE Contin Coens)
Toma sae
an
@)
i got A”
LT
Mares 2 Has as derived rl ae al constant fr rs ration;
kız = (kuknkiaf)"?
tec ad ar ie ate cont fro secure actos
hi bene cosa ees ecos,
iste equim constant for over css ren.
asa an ste coc anit des acracn fre difaenein fe encres
cuotas enel ls ny
Higher he valu of quam conse (Kz) o cos eco, evil eh tof lon
sant The our onan ca ted win "aloes
AS iin
Tina ht righ valu og wile Geneve value of And hence ate wt
bee tt of econ
Tighe vals of equi cont fr ros eto lees da te conan for ere
ration ae general ger han ef menda lagar,
Now latas cir th eros econ
LPO) P* (RUNES Jo Y" — (PO) RON)" o
Fortis ros reaction, e self exchange restos ae
(FO) + (Fe(H2O) 1 — [FezO)e Y" +(Fe(H20)6)°* ti)
CRAN DE HERNE) ]°* — RON) + [RUN Je 1?" Gi
‘The rte constant kyy and £32 for the self exchange reactions (i) and (i) are observed to be
42 Lal" 5 and 4.0% 10° L mot” 5” respectively and the equilibrium constant (£ 2) for cross
reaction (i)is2.1x10" and ÿ =0.85. Then rate constant 4 fr cross reaction (1 is calculated by the
expression :
fag = ikki?
= (42x20x10° 121x101! x085)!
4810? Lot 51
‘Thus, the caleulted value off» by Marcus-Huch equation is found tobe greater than those a
and ap. ILimplies that he rate of electron transfer in cross resto is faster then those of corresponding
self exchanges,
Some examples of outer sphere self exchanges and eros reactions with their second order
‘constants ae given in Table 7. and 7.6 respectively,
(0) Inner Sphere Mechanism
Jn inver sphere olectom tanser reactions, the oxidant and oduciat share a ligand in
«odian sphere to form a bridged compe, the lcton is the transfered trough the brid
ligand
Salient Features of Inner Sphere Mechanism
(0) One comple (the reductant) sable andthe other ie, the oxidant i inet
(2) The inert complex possesses atleast one ligand capable of bridging two metal ions to form
bridged intermediate and this bridged intermediates called a precursor complex.
©) Ofc, but not always, the Bridging ligand also transfered from oxidant o rota
transfer or non transfer o bridging and depends pon the relative stables of the a
“Te ligand wansfer is a good indicator tht electron transfer takes place by inne pl
imecbaisn. I there i no bridging ligand, then electron transfer docs not tae place by i
sphere mechanism, However ity take place by outer sphere mechanism a bridging hi
(tached to inert complex) is available but ot taster, hn the electron transfer may
citer by an inner or outer sphere mechanism.
(4) ithe (0%) or tag (nt orbitals fh de reactants participate in electron tafe by à
sphere mechanism In general these stas maybe HOMO of the reductant and LUMO o
‘oxidant, [both the reactants in an electron ran reaction involve orbital of same sym
oor alte activation energy iszequirl and leon transfer wlkbe fast If both thee
ae of different symmeties, greater acivaion enemy encompassing both str
deformation and electron configuration change is required, Such reaction wil be slower
those requiring no electron eonfigumticn change. Electron transfer by inner sphere mechan
istaster when electron transfer takes pace between ey (oro*)orbitl of oxidant and cede
(6) Inner sphere eco transfer eaton ae fer an similar reaction occuning hrougho
sphere mechanism.
(6) There of electron transfer increases fe brigi amd possess unsaturation or ete
conjugation.
“The electron transfer in inner sphere mechanism aks place through the following elementary |
inaqueous medium.
Toma sae
an
@)
i got A”
LT
Mares 2 Has as derived rl ae al constant fr rs ration;
kız = (kuknkiaf)"?
tec ad ar ie ate cont fro secure actos
hi bene cosa ees ecos,
iste equim constant for over css ren.
asa an ste coc anit des acracn fre difaenein fe encres
cuotas enel ls ny
Higher he valu of quam conse (Kz) o cos eco, evil eh tof lon
sant The our onan ca ted win "aloes
AS iin
Tina ht righ valu og wile Geneve value of And hence ate wt
bee tt of econ
Tighe vals of equi cont fr ros eto lees da te conan for ere
ration ae general ger han ef menda lagar,
Now latas cir th eros econ
LPO) P* (RUNES Jo Y" — (PO) RON)" o
Fortis ros reaction, e self exchange restos ae
(FO) + (Fe(H2O) 1 — [FezO)e Y" +(Fe(H20)6)°* ti)
CRAN DE HERNE) ]°* — RON) + [RUN Je 1?" Gi
‘The rte constant kyy and £32 for the self exchange reactions (i) and (i) are observed to be
42 Lal" 5 and 4.0% 10° L mot” 5” respectively and the equilibrium constant (£ 2) for cross
reaction (i)is2.1x10" and ÿ =0.85. Then rate constant 4 fr cross reaction (1 is calculated by the
expression :
fag = ikki?
= (42x20x10° 121x101! x085)!
4810? Lot 51
‘Thus, the caleulted value off» by Marcus-Huch equation is found tobe greater than those a
and ap. ILimplies that he rate of electron transfer in cross resto is faster then those of corresponding
self exchanges,
Some examples of outer sphere self exchanges and eros reactions with their second order
‘constants ae given in Table 7. and 7.6 respectively,
(0) Inner Sphere Mechanism
Jn inver sphere olectom tanser reactions, the oxidant and oduciat share a ligand in
«odian sphere to form a bridged compe, the lcton is the transfered trough the brid
ligand
Salient Features of Inner Sphere Mechanism
(0) One comple (the reductant) sable andthe other ie, the oxidant i inet
(2) The inert complex possesses atleast one ligand capable of bridging two metal ions to form
bridged intermediate and this bridged intermediates called a precursor complex.
©) Ofc, but not always, the Bridging ligand also transfered from oxidant o rota
transfer or non transfer o bridging and depends pon the relative stables of the a
“Te ligand wansfer is a good indicator tht electron transfer takes place by inne pl
imecbaisn. I there i no bridging ligand, then electron transfer docs not tae place by i
sphere mechanism, However ity take place by outer sphere mechanism a bridging hi
(tached to inert complex) is available but ot taster, hn the electron transfer may
citer by an inner or outer sphere mechanism.
(4) ithe (0%) or tag (nt orbitals fh de reactants participate in electron tafe by à
sphere mechanism In general these stas maybe HOMO of the reductant and LUMO o
‘oxidant, [both the reactants in an electron ran reaction involve orbital of same sym
oor alte activation energy iszequirl and leon transfer wlkbe fast If both thee
ae of different symmeties, greater acivaion enemy encompassing both str
deformation and electron configuration change is required, Such reaction wil be slower
those requiring no electron eonfigumticn change. Electron transfer by inner sphere mechan
istaster when electron transfer takes pace between ey (oro*)orbitl of oxidant and cede
(6) Inner sphere eco transfer eaton ae fer an similar reaction occuning hrougho
sphere mechanism.
(6) There of electron transfer increases fe brigi amd possess unsaturation or ete
conjugation.
“The electron transfer in inner sphere mechanism aks place through the following elementary |
inaqueous medium.
ea en OS
Formation of precursor complex
X +R—0M) —*[0—X—R] + H20
‘Activation of precursor complex
RR KR)"
«lec transfer CRE
Dissociation to separate products
[Ox —X—RI+H¿O => Ox(H,07" +R—X*
“Te ate lv forthe overall ración
a
X + Red SEO Rod OT + Red xt
a “
kk
E +
where Ay i the overall rate constant or 2nd and dr step.
A a
is Rates
{0x—x][Red] an
Ratew ky (Ox—X][Red] aa)
Ik >> ks, then the rte determining stp will be rearrangement an electron transfer within the
intermediate (Le, fission of te precursor complex). Ths, rate law will be =
1100] 3)
Now tus discuss some importante involving electron transfer by janerspeomectnism.
(A) Taube and his students have provided fst reaction involving electron anse by inser sphere
mechanism, The ave ection is:
LCoQN CU QUO) +5140" — [ColH30)6P°* +LCHEhO)sCH?* + NH
‘Low spin Highspia High spin a
CC) de) ad
or (anyon)? or (eon! ao? or) or)?
Iner Labile Labile net
In this reaction Co is reduced by Or and the beidging ligand CI" is tantened from
coordination sphere of cobalt tat fee.
LCA) GIP sine met and CI” is the bridging and.
di) Electron transferts place from e (@*)_0f[x(H20} 61°" o e (0*of{CANE)sCIP*-
“Ths, electro transfer by inner sphere mechanism is fas (cate constant (k)= 6x 10° Leo's")
“The various steps ofthe mechani of the reaction are shown below
dá) Chlorine atom of inert {Co(NHs) CI" complex while remaining firmly atached to Co)
‘replaces a water molecule from the labile [Cx(H20)¢. P* 10 form a bridged intermediate.
Los) CIE CO)" — ((H3N)sCo—C1—CxH120)s]* +10
Gi) Electron transfer takes place from Cr) to Co) through CI bridge in a manner as clectroa
flow between two eleczodes through sl bridge,
“This step is the rate determining stp. After transfer of electron from Cr? 1e Co*, Co} is
converted 10Co?* and te complex becomes high spin and labile. On the ther hand, Cr is
converted toCr™™ and the complex becomes inert,
3 x a ot
1 à i
[CH5N)5Go—C.-CANO) I" LEDs Co CI (LOST
nl aie Lie lest
ii) SinceCo? is now bbilesndCr* is ints the bridged comple intermediate ist in
Sicha way that chlorine am remains attached with chromium.
{tn 8-1 Ers0)5)"" — (Co) HERO
(ivy Io the last step the five coordinate [(Co(NH )s 1 species picks up water molecule o form
[Co(NHs)5(H20)]°* complex ion and this complex ion is hyérolyzed rapidly to give
{Co(H120)6]"* ion.
(CH) +0 — (CON) (BON
+510"
[Co(H1,0)6)°* + NEL"
Formation of precursor complex
X +R—0M) —*[0—X—R] + H20
‘Activation of precursor complex
RR KR)"
«lec transfer CRE
Dissociation to separate products
[Ox —X—RI+H¿O => Ox(H,07" +R—X*
“Te ate lv forthe overall ración
a
X + Red SEO Rod OT + Red xt
a “
kk
E +
where Ay i the overall rate constant or 2nd and dr step.
A a
is Rates
{0x—x][Red] an
Ratew ky (Ox—X][Red] aa)
Ik >> ks, then the rte determining stp will be rearrangement an electron transfer within the
intermediate (Le, fission of te precursor complex). Ths, rate law will be =
1100] 3)
Now tus discuss some importante involving electron transfer by janerspeomectnism.
(A) Taube and his students have provided fst reaction involving electron anse by inser sphere
mechanism, The ave ection is:
LCoQN CU QUO) +5140" — [ColH30)6P°* +LCHEhO)sCH?* + NH
‘Low spin Highspia High spin a
CC) de) ad
or (anyon)? or (eon! ao? or) or)?
Iner Labile Labile net
In this reaction Co is reduced by Or and the beidging ligand CI" is tantened from
coordination sphere of cobalt tat fee.
LCA) GIP sine met and CI” is the bridging and.
di) Electron transferts place from e (@*)_0f[x(H20} 61°" o e (0*of{CANE)sCIP*-
“Ths, electro transfer by inner sphere mechanism is fas (cate constant (k)= 6x 10° Leo's")
“The various steps ofthe mechani of the reaction are shown below
dá) Chlorine atom of inert {Co(NHs) CI" complex while remaining firmly atached to Co)
‘replaces a water molecule from the labile [Cx(H20)¢. P* 10 form a bridged intermediate.
Los) CIE CO)" — ((H3N)sCo—C1—CxH120)s]* +10
Gi) Electron transfer takes place from Cr) to Co) through CI bridge in a manner as clectroa
flow between two eleczodes through sl bridge,
“This step is the rate determining stp. After transfer of electron from Cr? 1e Co*, Co} is
converted 10Co?* and te complex becomes high spin and labile. On the ther hand, Cr is
converted toCr™™ and the complex becomes inert,
3 x a ot
1 à i
[CH5N)5Go—C.-CANO) I" LEDs Co CI (LOST
nl aie Lie lest
ii) SinceCo? is now bbilesndCr* is ints the bridged comple intermediate ist in
Sicha way that chlorine am remains attached with chromium.
{tn 8-1 Ers0)5)"" — (Co) HERO
(ivy Io the last step the five coordinate [(Co(NH )s 1 species picks up water molecule o form
[Co(NHs)5(H20)]°* complex ion and this complex ion is hyérolyzed rapidly to give
{Co(H120)6]"* ion.
(CH) +0 — (CON) (BON
+510"
[Co(H1,0)6)°* + NEL"
‘Am evidence o suport he ner phere mechanism i tha the reto cane tin ston
‘containing free isotopic chlorine (eg.,°°C1"), none of these labeled ions are found in the products.
Conversely if ion in [Co CH? isotopically labeled wih Che bc lis aways
ceased 10 coordination sb.
“The eucion is ist ore with eapettoxdan nd Gt ode wih eset rotate, ove
seaction of second ote,
Rate foi lreductan]
= (Co(NHS) CIP (Cr(H0) 6?
isthe second onder rat constant.
“Taube and his students have also provided a set of similar reactions. The general section is given
below
{COON }sX1* +20)" +SH130" — [Co(H20)6 17 +(Cx(H20}5 X}+ SNH
Where X = FO Br" NCST,NOG,SON”,S02 , PO}, N3,N3 et
À NowitX” bet furs FC LB" and 1” an larger he size ofthe asters
A rate of lecton trastes. 7
Sinesizeofhlideineenses fem F” to as F< CI"< Bee I~ and poliza ofthe tides
increases th soe oder. In the beige comple th halides more poarizod by higher chargedcaton
ie, Co°* ion. As the halide is polarized, induced dipole moment is developed in X atom as shown in
Figur 127 The induced dipole moment i the halogen atom tracts the else" and then
facilite the ae a lesson wast, Ths, we can say that larger the sie of hai, more wil bes
polaasbility and more willbeinducedipoleand hence he esierbethe lech re. Ts herte
of electron transfer follow the order: F-< CI"< Br-< 1°. 7
There reso many cassia whicheleeton transfer aes place by bah inner spheres outer sphere
‘mechanisms In sch reactions whic proceed by iane sphere pathway, election anse takes place in
bridged complex without aff ligand. Such a condition arses when the bring land salis
Ü original complex itn prod Fr example: * =
[FACE #1OtCn) I" — [FACE HCO(CNs >
This reactions proceda ol +
[FE HCC" — ((NC)5 Fe CN COHN) I=
1. Eseron tner
ET
[FEINE] +4Co(CN) (820)?
TheFe?* CN bond more stable than Co * —NC™ bord, Therefore electron transfer cours
‘without wane of CN ian
An another example of electron transfer that occurs by inner sphere mechanism without transfer of
ligand is
“os a 7
I + OO" — (clic (Hg 0)5}° E cidos
| Be.
CD + (CH ONE
Inthe bridged complex orprecusor complex, ater leon trans, e Bond betnen the reduced
metal ion and the bridge {fr(IIf)—Cl] is stronger than the bond between the oxidized metal ion and the
‘ridge {Ci( UL) —Cl}and the later willbe broken before the former. Thus, in this reaction [I:C1g]3" and
{Ce(H,0)4] ae more sabe thn [Cl 30)” and [CxH0)s CI?" respecte, the air
posible products, Ths eeacin indicates that ligand transfer i ota requiement of he inner
Sphere mechanism.
Mode felon nt dae constants or various nor pte actions givin Table 78
Remote Attack
the two metal ios inan activated bridge complex are coondinated t the only one atom ay CI}.
hen this i called adjacent attack. Pxampleof the adjacent attack is
[(egN)sCo~C1—Ce (H20}5 1%
Ihe two mea ions na activated bridge complex ae coordiated a vo irn atoms ofthe
din ligand, then ts call as remote attack. For example, consider te following rection:
‘containing free isotopic chlorine (eg.,°°C1"), none of these labeled ions are found in the products.
Conversely if ion in [Co CH? isotopically labeled wih Che bc lis aways
ceased 10 coordination sb.
“The eucion is ist ore with eapettoxdan nd Gt ode wih eset rotate, ove
seaction of second ote,
Rate foi lreductan]
= (Co(NHS) CIP (Cr(H0) 6?
isthe second onder rat constant.
“Taube and his students have also provided a set of similar reactions. The general section is given
below
{COON }sX1* +20)" +SH130" — [Co(H20)6 17 +(Cx(H20}5 X}+ SNH
Where X = FO Br" NCST,NOG,SON”,S02 , PO}, N3,N3 et
À NowitX” bet furs FC LB" and 1” an larger he size ofthe asters
A rate of lecton trastes. 7
Sinesizeofhlideineenses fem F” to as F< CI"< Bee I~ and poliza ofthe tides
increases th soe oder. In the beige comple th halides more poarizod by higher chargedcaton
ie, Co°* ion. As the halide is polarized, induced dipole moment is developed in X atom as shown in
Figur 127 The induced dipole moment i the halogen atom tracts the else" and then
facilite the ae a lesson wast, Ths, we can say that larger the sie of hai, more wil bes
polaasbility and more willbeinducedipoleand hence he esierbethe lech re. Ts herte
of electron transfer follow the order: F-< CI"< Br-< 1°. 7
There reso many cassia whicheleeton transfer aes place by bah inner spheres outer sphere
‘mechanisms In sch reactions whic proceed by iane sphere pathway, election anse takes place in
bridged complex without aff ligand. Such a condition arses when the bring land salis
Ü original complex itn prod Fr example: * =
[FACE #1OtCn) I" — [FACE HCO(CNs >
This reactions proceda ol +
[FE HCC" — ((NC)5 Fe CN COHN) I=
1. Eseron tner
ET
[FEINE] +4Co(CN) (820)?
TheFe?* CN bond more stable than Co * —NC™ bord, Therefore electron transfer cours
‘without wane of CN ian
An another example of electron transfer that occurs by inner sphere mechanism without transfer of
ligand is
“os a 7
I + OO" — (clic (Hg 0)5}° E cidos
| Be.
CD + (CH ONE
Inthe bridged complex orprecusor complex, ater leon trans, e Bond betnen the reduced
metal ion and the bridge {fr(IIf)—Cl] is stronger than the bond between the oxidized metal ion and the
‘ridge {Ci( UL) —Cl}and the later willbe broken before the former. Thus, in this reaction [I:C1g]3" and
{Ce(H,0)4] ae more sabe thn [Cl 30)” and [CxH0)s CI?" respecte, the air
posible products, Ths eeacin indicates that ligand transfer i ota requiement of he inner
Sphere mechanism.
Mode felon nt dae constants or various nor pte actions givin Table 78
Remote Attack
the two metal ios inan activated bridge complex are coondinated t the only one atom ay CI}.
hen this i called adjacent attack. Pxampleof the adjacent attack is
[(egN)sCo~C1—Ce (H20}5 1%
Ihe two mea ions na activated bridge complex ae coordiated a vo irn atoms ofthe
din ligand, then ts call as remote attack. For example, consider te following rection:
Rent tc
ICQ (SON GO) “ATES sn Co— SON CO) 1"
(ESDSGO-SCN - Cr (10), 1 LH (13 20¿CAO) +) (CSD
+510"
[Co(HzO)6]?* + SNH
Tn the electron transfer reaction between [Co(NHs)5(SCN)}* and (Cr(H70)«]**, an adjacent
attack also oocurs o form the (Co(H120)6]?* and (Cr(H10)s (SON) products.
x
¡ANCASH HO)" AEE (NSS CO)"
N
(econ rater
€
LENCO S- CO" — gg > RO HOM HALO) (SCA
+580!
ECO) P* + SNH
Indian ant acne io COSO" is 0% andi the laterthe yield of
ACr(H20)s (SCN)}* is onty 30%. ese se
‘An another exemple of emote atack is gen below:
{EN} sCo(NCS)]?* +[Co(CN)s 7 —> [CH3N)s -Co~NCS~CoCN)
+0
ESN) GOLO)F* HOCH 5 SON
| si"
(Co(H20)6 1" + SNH}
Since(Co(NH3)5]?* isa hard acid unit and {Co(CN)s = is sof acid ni, the stable N-bonded
LCA) NCS} is converted o more sable Ca(CN) (SCN)
A remote attack also forms the linkage isomers as show in the following reaction:
oe pe]
[une <) HIGO(CN)P Rese Tann“
Isomeciaon +120
+ SH30*
[Co{CN)s(NOZ)!” [Co(HzO)]* + SNAG
Im this reaction the kinetically favoured niit comple, [Co(CN)sONOJ”"isomerises to
thenmodynamically favoured the complex, [Co(CN) (O2)
‘Table 7 Mode of Electron Transfer and Rate Constants for Some Outer Sphere Reaction
{Ci 206)" {Co(NH Jo] * 10x10?
E
1er || ACo(Phen)s 30
uno [een [Rat een? lors ao
mor ot 10?
MEO [ee [ram [a [rot | 72104
WER" (Co(Phen)s 1" 38x10?
Wane Jaren? met Leon lee | so
ICQ (SON GO) “ATES sn Co— SON CO) 1"
(ESDSGO-SCN - Cr (10), 1 LH (13 20¿CAO) +) (CSD
+510"
[Co(HzO)6]?* + SNH
Tn the electron transfer reaction between [Co(NHs)5(SCN)}* and (Cr(H70)«]**, an adjacent
attack also oocurs o form the (Co(H120)6]?* and (Cr(H10)s (SON) products.
x
¡ANCASH HO)" AEE (NSS CO)"
N
(econ rater
€
LENCO S- CO" — gg > RO HOM HALO) (SCA
+580!
ECO) P* + SNH
Indian ant acne io COSO" is 0% andi the laterthe yield of
ACr(H20)s (SCN)}* is onty 30%. ese se
‘An another exemple of emote atack is gen below:
{EN} sCo(NCS)]?* +[Co(CN)s 7 —> [CH3N)s -Co~NCS~CoCN)
+0
ESN) GOLO)F* HOCH 5 SON
| si"
(Co(H20)6 1" + SNH}
Since(Co(NH3)5]?* isa hard acid unit and {Co(CN)s = is sof acid ni, the stable N-bonded
LCA) NCS} is converted o more sable Ca(CN) (SCN)
A remote attack also forms the linkage isomers as show in the following reaction:
oe pe]
[une <) HIGO(CN)P Rese Tann“
Isomeciaon +120
+ SH30*
[Co{CN)s(NOZ)!” [Co(HzO)]* + SNAG
Im this reaction the kinetically favoured niit comple, [Co(CN)sONOJ”"isomerises to
thenmodynamically favoured the complex, [Co(CN) (O2)
‘Table 7 Mode of Electron Transfer and Rate Constants for Some Outer Sphere Reaction
{Ci 206)" {Co(NH Jo] * 10x10?
E
1er || ACo(Phen)s 30
uno [een [Rat een? lors ao
mor ot 10?
MEO [ee [ram [a [rot | 72104
WER" (Co(Phen)s 1" 38x10?
Wane Jaren? met Leon lee | so
RRS SERE Corillo Chel
‘Table 7.8 Mode of Electron Transfer and Rate Constant for Various Inner Sphere Electron.
Transfer Reactions,
similar reaction can be explained on the basis of symmetries ofthe eductant orbital from which an
eco is o be transferred and the oxidant orbital into whic the electron goes.
‘The general observations obtained ftom Table 77 and7.8 ae given in Table 79,
‘Table 7.9: Acceleration of Rate of Electron Transfer
on going from Outer Sphere to Inner Sphere Mechanism
Ñ #0
{oon}, 2 pr
Losa] [o + [3 CICR rar ETS
[Een ar 8 seat
ar = asm
CB | | enon” jara: te are”
CE - sui
‘Acceleration of Rate of Electron Transfer on going from Outer Sphere to Inner
‘Sphere Mechanism for Similar Reactions
Electron rane fiom [Cx (HO) ° tof CofNHs)]* takes place by outer sphere mechanism but
the rate of electron transfer is very slow (E=16x10" L'nol à) because electron transfer takes
placofrom [Cr(4¿0)6 1 to{Co(NHs )Jandatertansterfelectontheeis an appreciable chango in
‘bond length which requires a high activation eng.
ICONS Del HOHER >
Lol + {CHHO}6 1"
Lowsyin Highspin Highspin =
Inert Labio
de ee Cr) 6.8)
Er or) (ot
Ti reaction does a occur by inne sphere mechanism because te net complex {Co(NHs 63°"
bas no brigingligand.
“Onthe other hand, fone ammonia ligand an Co is replaced by CT ligand, reaction would occur
y ier sphere mechanism because CI Jo is taste to he oxidized oductant, andthe cate of
reaction is large (k=6x10° Lot sl), Electron taser by inne sphere mechani: has been
‘cemendously accelerated relative to the outer sphere mechanism for the similar reaction. The
sccelerton of election transfer by inner sphere mechanism relative to outer sphere mechanism for
7 # Re
e of vera gi
xt m VAR No acceleration
From the Table 7.9. ti concluded da iiheelcrn nse takes place fom x* ofthe reductnt
to x ofthe oxidant, then this electron anses consider tobe occuring by outer sphere mechani
‘ursotby iter sphere mechanism
‘general cat of electron ense acceleration acc on ging fiom an outer preto inner sphere
aechan in Similar ration. The maximun accterion vous when HOMO and LUMO of both
oder and oxidant io. [Fo HOMO and LUMO are * hen letrn raster as by outer
here mechanism and no acceleration occur on ging om outer sphere to inner sphere mechanism. In.
rhe reactions when HOMO and LUMO areo "and R*or x*ando ‘respectively, activation energy is
required for electron transfer to a from til because in sch eases bond length is changed during
transfer of electron and thas, there is acceleration iat electron transfer on going fom outer Sphere
ter sphere mechanism,
Inner Sphere Reactions with Complexes Containing Drganic Bridging Ligands
Mostexensvey studied completes conning organi bdeing ligands re carboxylate complexes
such 25 pentaamminebenaatecobal( ll) (Fi 728) and amine complexes such 2
‘petaanminesonicotsamide coal complexes Fg, 129)
MT | ae
|
‘Table 7.8 Mode of Electron Transfer and Rate Constant for Various Inner Sphere Electron.
Transfer Reactions,
similar reaction can be explained on the basis of symmetries ofthe eductant orbital from which an
eco is o be transferred and the oxidant orbital into whic the electron goes.
‘The general observations obtained ftom Table 77 and7.8 ae given in Table 79,
‘Table 7.9: Acceleration of Rate of Electron Transfer
on going from Outer Sphere to Inner Sphere Mechanism
Ñ #0
{oon}, 2 pr
Losa] [o + [3 CICR rar ETS
[Een ar 8 seat
ar = asm
CB | | enon” jara: te are”
CE - sui
‘Acceleration of Rate of Electron Transfer on going from Outer Sphere to Inner
‘Sphere Mechanism for Similar Reactions
Electron rane fiom [Cx (HO) ° tof CofNHs)]* takes place by outer sphere mechanism but
the rate of electron transfer is very slow (E=16x10" L'nol à) because electron transfer takes
placofrom [Cr(4¿0)6 1 to{Co(NHs )Jandatertansterfelectontheeis an appreciable chango in
‘bond length which requires a high activation eng.
ICONS Del HOHER >
Lol + {CHHO}6 1"
Lowsyin Highspin Highspin =
Inert Labio
de ee Cr) 6.8)
Er or) (ot
Ti reaction does a occur by inne sphere mechanism because te net complex {Co(NHs 63°"
bas no brigingligand.
“Onthe other hand, fone ammonia ligand an Co is replaced by CT ligand, reaction would occur
y ier sphere mechanism because CI Jo is taste to he oxidized oductant, andthe cate of
reaction is large (k=6x10° Lot sl), Electron taser by inne sphere mechani: has been
‘cemendously accelerated relative to the outer sphere mechanism for the similar reaction. The
sccelerton of election transfer by inner sphere mechanism relative to outer sphere mechanism for
7 # Re
e of vera gi
xt m VAR No acceleration
From the Table 7.9. ti concluded da iiheelcrn nse takes place fom x* ofthe reductnt
to x ofthe oxidant, then this electron anses consider tobe occuring by outer sphere mechani
‘ursotby iter sphere mechanism
‘general cat of electron ense acceleration acc on ging fiom an outer preto inner sphere
aechan in Similar ration. The maximun accterion vous when HOMO and LUMO of both
oder and oxidant io. [Fo HOMO and LUMO are * hen letrn raster as by outer
here mechanism and no acceleration occur on ging om outer sphere to inner sphere mechanism. In.
rhe reactions when HOMO and LUMO areo "and R*or x*ando ‘respectively, activation energy is
required for electron transfer to a from til because in sch eases bond length is changed during
transfer of electron and thas, there is acceleration iat electron transfer on going fom outer Sphere
ter sphere mechanism,
Inner Sphere Reactions with Complexes Containing Drganic Bridging Ligands
Mostexensvey studied completes conning organi bdeing ligands re carboxylate complexes
such 25 pentaamminebenaatecobal( ll) (Fi 728) and amine complexes such 2
‘petaanminesonicotsamide coal complexes Fg, 129)
MT | ae
|
ere E ee
Rate of electron transfer by inner phere mechanism of these complexes canbe controled by the
point of attack bythe reductant on the bridging ligand serie effects of bridging ligand and the electronic
ture ofthe bridging ligand and the sduciblit ofthe complexes, These complexes bebave as
‘oxidant and second oder kinetics ae observed fr these reactions. Electron transfer reactions by inner
sphere mechanisms ofthese complexes involve remote attack ofthe reductant rather than the adjacent
‘Huck (ce, attack onthe atom attached diet tothe meal ion ofthe oxidant).
‘thas been observed tha the eduction of acidopentaarminecobalt(It} complexes by Ce) ion ia
aqueots solution involves the remote atack of CI) ion at he carbonyl oxygen of tre cale
group. The at of reduction by CI) decreases with increasing steric hindrance of the organic group as
given below :
a o q o a
| i
(HN) sCo—-0—-C—H > —0- CH, > 00-041 > 0 CC
| |
a ñ
och
N!
> 06-005
1
a
rderofrate constant.
Erectron tenes ia atackat asi evea mare remote ab carbon oxygen cathy! opis
also posible and has been observed in the ection of Col), Ruf) and Ri) complees of
Substtted pyridines. The Coll) complexes of pyridine of COIN, for example
Pentaamincpyrdincobal(0D, reacts rele slowly with CHI) in aqueous solution to give
[Co(NH;)s(py)}** and {Cr(H1;0)¢]** by outer sphere mechanism as there is no bridging ligand on
Cof) ion. The complexes of subtil prties, for example, pentsmmineisoncoinanide-
bal) complex ion Fi, 7.20) resets much more fase with Cr) in aqucous solution to give he
product shown in Fg. 7.300) by ie phere mechanism. In his esction, te atack of Cx) sa the
remote oxygen ofthe cary! growpofioncatinamide and ofthe complex [Pi 730) Dis ata
Of Cul) atthe oxygen of the carbonyl group is due to the Lewis base propeies of amides in which
Oxygen of carbonyl group beaves a donor ie,
a ms e
Y «0
ws “HOG OF" SO + Wo y
IN, nh à no Ly
nl Nam 1o/| Mo
ty te
a
CRC «svt
Fission of the Successor Complex
From equation (7.1), itcan be argued hat the inner sphere reduction rates ean be controle by rate
of formation of the precursor complex and electron transfer within the precursor intermediate. This
situation arises only when ky >> ky. However the overall ate of electron transfer ean be controle by
the rate of fission ofthe successar complex but itis possible when Az >> kz and ka becomes eal o
Kis
where K =k da
Letus consider, for example, tbereductionofpentaamoincisonicotinamidecobaltI) with Crt) in
‘aqueous solution. When peataammineisonicatinanidecobali(It reacts with CU), precursor formation
dnd leo waster sro gie ylbm-oange inci sucesor complex contain RU) nd
Cal) This process is completed within the time of mixing. The binuclear successor complex is quite
stable and decomposes slowly to give pentaranineisonicotinamideruthentwm() and CA) under
‘tre different conditions.
s
Pas CON
oot a
ES
m
cta Lm] steno
“The stability ofthe successor complex is due 1 he reason that Ruf) and CT) are quite net
substitution, Since substation rescions in octahedral complexes generally occur by dissociaive(D)
‘mechanism, the dissociation ofthe suceestor complex and formation ofthe product are low. Inthe fist
route (or ke path, he Suecessor complex dissociates spontaneously and slowly to give products. The
Rate of electron transfer by inner phere mechanism of these complexes canbe controled by the
point of attack bythe reductant on the bridging ligand serie effects of bridging ligand and the electronic
ture ofthe bridging ligand and the sduciblit ofthe complexes, These complexes bebave as
‘oxidant and second oder kinetics ae observed fr these reactions. Electron transfer reactions by inner
sphere mechanisms ofthese complexes involve remote attack ofthe reductant rather than the adjacent
‘Huck (ce, attack onthe atom attached diet tothe meal ion ofthe oxidant).
‘thas been observed tha the eduction of acidopentaarminecobalt(It} complexes by Ce) ion ia
aqueots solution involves the remote atack of CI) ion at he carbonyl oxygen of tre cale
group. The at of reduction by CI) decreases with increasing steric hindrance of the organic group as
given below :
a o q o a
| i
(HN) sCo—-0—-C—H > —0- CH, > 00-041 > 0 CC
| |
a ñ
och
N!
> 06-005
1
a
rderofrate constant.
Erectron tenes ia atackat asi evea mare remote ab carbon oxygen cathy! opis
also posible and has been observed in the ection of Col), Ruf) and Ri) complees of
Substtted pyridines. The Coll) complexes of pyridine of COIN, for example
Pentaamincpyrdincobal(0D, reacts rele slowly with CHI) in aqueous solution to give
[Co(NH;)s(py)}** and {Cr(H1;0)¢]** by outer sphere mechanism as there is no bridging ligand on
Cof) ion. The complexes of subtil prties, for example, pentsmmineisoncoinanide-
bal) complex ion Fi, 7.20) resets much more fase with Cr) in aqucous solution to give he
product shown in Fg. 7.300) by ie phere mechanism. In his esction, te atack of Cx) sa the
remote oxygen ofthe cary! growpofioncatinamide and ofthe complex [Pi 730) Dis ata
Of Cul) atthe oxygen of the carbonyl group is due to the Lewis base propeies of amides in which
Oxygen of carbonyl group beaves a donor ie,
a ms e
Y «0
ws “HOG OF" SO + Wo y
IN, nh à no Ly
nl Nam 1o/| Mo
ty te
a
CRC «svt
Fission of the Successor Complex
From equation (7.1), itcan be argued hat the inner sphere reduction rates ean be controle by rate
of formation of the precursor complex and electron transfer within the precursor intermediate. This
situation arises only when ky >> ky. However the overall ate of electron transfer ean be controle by
the rate of fission ofthe successar complex but itis possible when Az >> kz and ka becomes eal o
Kis
where K =k da
Letus consider, for example, tbereductionofpentaamoincisonicotinamidecobaltI) with Crt) in
‘aqueous solution. When peataammineisonicatinanidecobali(It reacts with CU), precursor formation
dnd leo waster sro gie ylbm-oange inci sucesor complex contain RU) nd
Cal) This process is completed within the time of mixing. The binuclear successor complex is quite
stable and decomposes slowly to give pentaranineisonicotinamideruthentwm() and CA) under
‘tre different conditions.
s
Pas CON
oot a
ES
m
cta Lm] steno
“The stability ofthe successor complex is due 1 he reason that Ruf) and CT) are quite net
substitution, Since substation rescions in octahedral complexes generally occur by dissociaive(D)
‘mechanism, the dissociation ofthe suceestor complex and formation ofthe product are low. Inthe fist
route (or ke path, he Suecessor complex dissociates spontaneously and slowly to give products. The
second route (or k pat) depends on (OH™} The hydroxide ion abstracts proton from Caf} bound
‘water ofthe saoessor complex and dissociates to give products.
o— bau il
und
Etre. Cn
E HALLO
lua] DS
“Te third route (ok path) depads on [OH Jas well as excess Of {Cr} In this path, the OH
ooo on] “*
vont i ON sac a cic wi
tein | oun =e
between this complex ion and unreacted Cl) and a bridge of the type nn is
formed [Fig,731(8)] and an inner sphere electron transfer takes place fom Ci) to CM) ranting in
the species (B).
fan ña
Since Cll is labile and CUT) is inet, therefore, Cal) is more sucepile to substitution
reactions tan CU, The complex (31) which now contas Cx] instead of CAD depre
° à
E
ed [RATEN] co cn anton. Se
the & path is catalyzed by excess of CHIN) this path is the most rapid of the three decomposition paths.
‚The simultaneous transfer oftwo or more electons by en outer sphere mechanism bas not yet been
«established because it would involve equalizing bond lengths in species of which one contain two or
more bonding electons than te other and requires high activation energy. The two electron transfer has
‘been observed to take place by inner sphere mechanism
One ofthe best two electron transfer reactions, for example, i the [Pufn) * catalyzed exchange
fradioactive "CI" for chloride bound to crans-{Pt(en}aCla]*.
ans ach + tar ET,
The rate law foc this reaction is:
Rate = kpl Pe} Cr
where Pel! and PLV stand for {P¥en)2}°* and [Pxen) Ci, ]** respectively. The mechanism
propose involves rapid ado of radioactive chloride ("CI") othe (den)? to form 2 five
‘coordinate (Ptfen)z* CIJ" which then forms a six coordinate, inner sphere bridged biauclear complex
with (Pen) >Cla]?* The tanster of two a * electrons accompinied by the transfer ofa Biding
chloride in the opposite dicton between the PU) and PHIV) complexes readily occu followed by
breaking ofthe red complex,
Pen rá — ein
trans Penya ICA" +
2
&
+ Ea =
(ya or L Jo =
a i ae
. hun
o Cee On
i ims
RO “( o; on
al (ke ”,,
trans spon, Pene" + OF
:
= OR»
I
‘water ofthe saoessor complex and dissociates to give products.
o— bau il
und
Etre. Cn
E HALLO
lua] DS
“Te third route (ok path) depads on [OH Jas well as excess Of {Cr} In this path, the OH
ooo on] “*
vont i ON sac a cic wi
tein | oun =e
between this complex ion and unreacted Cl) and a bridge of the type nn is
formed [Fig,731(8)] and an inner sphere electron transfer takes place fom Ci) to CM) ranting in
the species (B).
fan ña
Since Cll is labile and CUT) is inet, therefore, Cal) is more sucepile to substitution
reactions tan CU, The complex (31) which now contas Cx] instead of CAD depre
° à
E
ed [RATEN] co cn anton. Se
the & path is catalyzed by excess of CHIN) this path is the most rapid of the three decomposition paths.
‚The simultaneous transfer oftwo or more electons by en outer sphere mechanism bas not yet been
«established because it would involve equalizing bond lengths in species of which one contain two or
more bonding electons than te other and requires high activation energy. The two electron transfer has
‘been observed to take place by inner sphere mechanism
One ofthe best two electron transfer reactions, for example, i the [Pufn) * catalyzed exchange
fradioactive "CI" for chloride bound to crans-{Pt(en}aCla]*.
ans ach + tar ET,
The rate law foc this reaction is:
Rate = kpl Pe} Cr
where Pel! and PLV stand for {P¥en)2}°* and [Pxen) Ci, ]** respectively. The mechanism
propose involves rapid ado of radioactive chloride ("CI") othe (den)? to form 2 five
‘coordinate (Ptfen)z* CIJ" which then forms a six coordinate, inner sphere bridged biauclear complex
with (Pen) >Cla]?* The tanster of two a * electrons accompinied by the transfer ofa Biding
chloride in the opposite dicton between the PU) and PHIV) complexes readily occu followed by
breaking ofthe red complex,
Pen rá — ein
trans Penya ICA" +
2
&
+ Ea =
(ya or L Jo =
a i ae
. hun
o Cee On
i ims
RO “( o; on
al (ke ”,,
trans spon, Pene" + OF
:
= OR»
I
Rao recon in which the oxidant and rd change ei alain sats by an equal
number of waits are called complementary reactions, For examples:
St Ste
Sat + Hg?! — So’ + Hg?
[FIT FACE — [PCS] FC
LCI) +ICO(NH3)6Y* ——> CON: 6 + CNE Je?"
Non complementar reactions, on the oler hand, are reacios in which oidtion states of the
reactants (xian and ecucants) cage bya diera number of unis. a hese reactions, diferent
uber ofmoleules of oxidant and reductant are involved inthe choc equations. For example,
Mo(VU) + SRe(Ut) —> Mol) + SF)
2 eID) + Soll) ——> 2Fe{) +SaIV)
CID) + THEM) — 20410 + TI
20H) + PLV) — 2 + PAT)
CV) + 3FeQ1) — CAD + FD)
Non:complementary reactions proceed in multiple steps, each step involving a single electron
transfer. In these reactions, intermediates of unsable oxidation states are formed, For example,
seduction a CV) by Fell) has been proposed to take place inthe fomation of CV) and CH(IV) as
intermediates before the product CII) is formed.
CVD+ SF) —> CH) +3Fe)
Mechanism ofthis reaction is
a
CU Fea) == CH) + FD
CV) + Fett) 2 CV) + FI)
CV) + Fett) ESC) + Fett)
‘The rate law for such a mechanism is given as
ASI) [FEA
re) RFID)
Similar, in the oxidation of Fe) by TIN has been found to be fs order vih espect to each
reactant, suggesting the formation of TU as an intermediate,
2Re(t) + THA) — 2F (ID) + THA)
Rat
A Ro MS ARR
Mechanism
RAR
equ TG — > Fe + TH) 0)
tance
Ta + Ft TD + Fea i)
‘Wheat forasinthe couse ofresetion or when tis added nia te reverse of reaction)
‘ua + QU) THU + Fe) ti)
comets forthe TID formed
Since iy aso metals fora compounds in which hey exit a age of oxidation sates
differing by one unit, their ions are used as good catalyst for non-complementary redox reactions. Thus,
for example, the oxidation of Cx(ll) by peroxodisulphate is catalyzed by Ag” possibly through the
fonction varios intermediate and th following mechanism bas een suggested
AMD +802" — Ag) +280
AB) + Ag) — 2Agtt
Ark) + CU) — AD CAI)
Ag) + CV) — AR) + CV)
Ag +Cr(V) — AgfD + CV)
Synthesis of Coordination Compounds using Electron Transfer Reactions
“The separation of racemic mixture int its d and msi cale resolution. Sine the physical
and chemical properties ofthe d and forms (ie, enantiomers fa complex such 2 [Co(en) JCI are
‘ental except forthe interaction with plane polarize ligt, they can not be Separated by ordinary
method ike factional dstilation, factional erysallizatio et Ifthe horde ons of Co(en) JC are
replacedby optically active ana, ik arate ion, th resuig sls might differ in properties such as
solu Cole); is easly resolved by replacing wo chloride ons by bear ion, followed by
fractional crystalizaion. When d-artete ion is added to the soltion of acemie mixture of d+ and
some offCo(ea)s JC complex, woof the CI ioasind-and some are replace by the d-airate
‘on abbreviated as (d-tart)?” or (+-tart) % and two salts (+){Co(en) JCHd- tat) abbreviated as (++)
and (-HCO() IC tar) abbreviated as (- (1) forms. These salt pais ae aot mor images
eau he datation has same configuration in cachaltnd tcs alisar therefor, diasteiomers,
9 -{Cofer)s}C1s + (a tart)? — (4) {Coles} (tar) 1201
€)-{Co(ea)sJCly + (d- um)?” — (-)-[Colen)s]01 ta) 1200
Upon cysallizaion, the (+) Con) JC tart) is preis. from the solution leaving
()-{Co(ex)s JCM tar) inthe mother Liquor. The molt liquor becomes a thick gelatinous mass
fire eystization of (-)-(Co(en) JCI - ar). Te separated dastromers containing dtaruate
canbe converted to the active chloride enantiomers (Le. active d- and Ecloide complexes) by adding,
onen HCI which is an optically inactive compound.
number of waits are called complementary reactions, For examples:
St Ste
Sat + Hg?! — So’ + Hg?
[FIT FACE — [PCS] FC
LCI) +ICO(NH3)6Y* ——> CON: 6 + CNE Je?"
Non complementar reactions, on the oler hand, are reacios in which oidtion states of the
reactants (xian and ecucants) cage bya diera number of unis. a hese reactions, diferent
uber ofmoleules of oxidant and reductant are involved inthe choc equations. For example,
Mo(VU) + SRe(Ut) —> Mol) + SF)
2 eID) + Soll) ——> 2Fe{) +SaIV)
CID) + THEM) — 20410 + TI
20H) + PLV) — 2 + PAT)
CV) + 3FeQ1) — CAD + FD)
Non:complementary reactions proceed in multiple steps, each step involving a single electron
transfer. In these reactions, intermediates of unsable oxidation states are formed, For example,
seduction a CV) by Fell) has been proposed to take place inthe fomation of CV) and CH(IV) as
intermediates before the product CII) is formed.
CVD+ SF) —> CH) +3Fe)
Mechanism ofthis reaction is
a
CU Fea) == CH) + FD
CV) + Fett) 2 CV) + FI)
CV) + Fett) ESC) + Fett)
‘The rate law for such a mechanism is given as
ASI) [FEA
re) RFID)
Similar, in the oxidation of Fe) by TIN has been found to be fs order vih espect to each
reactant, suggesting the formation of TU as an intermediate,
2Re(t) + THA) — 2F (ID) + THA)
Rat
A Ro MS ARR
Mechanism
RAR
equ TG — > Fe + TH) 0)
tance
Ta + Ft TD + Fea i)
‘Wheat forasinthe couse ofresetion or when tis added nia te reverse of reaction)
‘ua + QU) THU + Fe) ti)
comets forthe TID formed
Since iy aso metals fora compounds in which hey exit a age of oxidation sates
differing by one unit, their ions are used as good catalyst for non-complementary redox reactions. Thus,
for example, the oxidation of Cx(ll) by peroxodisulphate is catalyzed by Ag” possibly through the
fonction varios intermediate and th following mechanism bas een suggested
AMD +802" — Ag) +280
AB) + Ag) — 2Agtt
Ark) + CU) — AD CAI)
Ag) + CV) — AR) + CV)
Ag +Cr(V) — AgfD + CV)
Synthesis of Coordination Compounds using Electron Transfer Reactions
“The separation of racemic mixture int its d and msi cale resolution. Sine the physical
and chemical properties ofthe d and forms (ie, enantiomers fa complex such 2 [Co(en) JCI are
‘ental except forthe interaction with plane polarize ligt, they can not be Separated by ordinary
method ike factional dstilation, factional erysallizatio et Ifthe horde ons of Co(en) JC are
replacedby optically active ana, ik arate ion, th resuig sls might differ in properties such as
solu Cole); is easly resolved by replacing wo chloride ons by bear ion, followed by
fractional crystalizaion. When d-artete ion is added to the soltion of acemie mixture of d+ and
some offCo(ea)s JC complex, woof the CI ioasind-and some are replace by the d-airate
‘on abbreviated as (d-tart)?” or (+-tart) % and two salts (+){Co(en) JCHd- tat) abbreviated as (++)
and (-HCO() IC tar) abbreviated as (- (1) forms. These salt pais ae aot mor images
eau he datation has same configuration in cachaltnd tcs alisar therefor, diasteiomers,
9 -{Cofer)s}C1s + (a tart)? — (4) {Coles} (tar) 1201
€)-{Co(ea)sJCly + (d- um)?” — (-)-[Colen)s]01 ta) 1200
Upon cysallizaion, the (+) Con) JC tart) is preis. from the solution leaving
()-{Co(ex)s JCM tar) inthe mother Liquor. The molt liquor becomes a thick gelatinous mass
fire eystization of (-)-(Co(en) JCI - ar). Te separated dastromers containing dtaruate
canbe converted to the active chloride enantiomers (Le. active d- and Ecloide complexes) by adding,
onen HCI which is an optically inactive compound.
(9-[Cofen) CIA a) + CL — (+) [Clea ICh + (ar
(=)-[Cofen)a JCKA ta) +2HC1 —(-}-[Cofen) ICI + (4 tart)?
"The soluble (-)-[Co(en) 3 ]OU(d - tart) can also be separated from the mother liquor by the use of
electon transfer reaction, When small aout of elendimine and CoCI) -6H0 which form
{Osten la, are added tothe mother quo, clon taster reaction by outer sphere mechanism
occurs besveen [Co(en) Cl formed with equal amount of the d- and & eneniomers and
(Coen) IC tar),
Jen -(cotems Ft +1 Loan O-Ton! —
JE ola PUE Cafes) + (D-LCoten)s PF
Thelaterfonn(-)-[Onden)s Y rapidyaoemizesta(+)-an(-)-(Co(es)a7”* dueto tb adion
of small amount of ethylenediamine and CoCl 50. The aber products of the electron transfer
reaction is racemic mixture ofthe santos of C(e)s The (isomer ofthe ney formed
oft compleis precipita leaving (ise ine oie gor, which egin undergoes electron
transfer with [Co(en); ]** and again a racemic mixture uf [Oofem);]°* is obtained, the (+)-isomer of
whi again precipitates leaving (-) some inthe solution. In is process al ofthe (-}enaniomer
txiginally preset ate converted into the (+)-caniome. Aleraively if trate used instead of
arte a stating materi ll ofthe (amie canbe converted into (enantiomer. In is
process the yield is approximately 75%.
Synthesis of [Cr(bpy) a(H20)2]** or [Cr(phen)2(H20)21%*
‘lectrochemical eduction offCxpter)s}™* any} in aqueous solution leads ultimately
to the production of (Cr(phen)2(H20}21°* and (pp (H20)2 D.
ea
eu wn
RE)
vee U:
wi Ny
Ape,
Ein =009Y
In the this reaction, the [Cx(phen)s À formed is labile1o substitution and one o-phenanthroline
Higand is replaced by two water molecules and (Crphen)a(4120),1* is formed. This ion undergoes
electron transfer with (Cr(phen)s ** which is presuming to be still present to produce the final product,
TCxpben)2(4120)2 1”.
BEER TERN
Be
se
B
ICKAA) PT +210 | [CHAR (HO) + AA
[CHAO 7" CP" ET [OAA)2(H2O)27* HEC?
where AA is either o-phen or bpy.
Inhas been experimentally observed hat seme selatvely ne substance may enter int sscinin
suc way either to dire he eatonst different poductorto catalyze the reaction
Delepine has studied Rhodiumfül) complexes of amine ligands io aqueous and waterethanal
solutions, Delepine hs observed that pyridine recs with No RECI] in aquoous slain to give
{Rhy sCls} This compound is insoluble. Therefore, the reaction stops at ths stage and futher
substitution of a chloride by fourth molecule of pyridine to give [Rixpy)4Cl ]° becomes difficult and
requires lengthy reflux, To overcome this difficulty, Delepine has added ethanol with the expectation
‘that the complex {Rh(py);Cis Jbecomes soluble with the formation of [Rixpy)¿Cl 3* . In this reaction,
‘ethanol as a solvent behaves as a catalyst and diverts the reaction to form {Rhipy) <Cl2]* rather than
TRh(py)3Cl ] complex. As à result of addition of ethanol, the reaction between Nas{RhCle] and
ppidime in squeous-chanol solution prosets immediately and qualitatively obtain the crystals of
{RH(s)4Cl product at room temperature without formation of another intermediate.
aces hin
agency LE hi
me comes
SY 5 a
“ep mle
mo
a
Ch ho)
‘The mechanism and kinetics of the.abovereaction are quite similar to that for the PHII)-PKIV) redox
reaction discussed erie. The fist sep involves he edition of RI) to RD) by han. Ba e
species in which RI) is produced isnot ksown. Although, it is observed that [Rhipy)a]* is
finned rpily as pytiine is used in excess. Th ion are now set forthe formation of
[Rhipy)aCl2]* by a mechanism indentical 10 a PUIN-PUIV) two electron transfer reaction. It is
experimentally observed that [RKC] does or involved in this mechanism, The addon of
‘ehtanol to the aqueous solution leads to the formation of [Rh(py)aCl2J* not by solubilizing
{HCl Joutby athe ating ea ring agent
IRMHZOJCISP* +C¿HSOH — Riff) complex +CH,CHO
Ro spy Ri"
(=)-[Cofen)a JCKA ta) +2HC1 —(-}-[Cofen) ICI + (4 tart)?
"The soluble (-)-[Co(en) 3 ]OU(d - tart) can also be separated from the mother liquor by the use of
electon transfer reaction, When small aout of elendimine and CoCI) -6H0 which form
{Osten la, are added tothe mother quo, clon taster reaction by outer sphere mechanism
occurs besveen [Co(en) Cl formed with equal amount of the d- and & eneniomers and
(Coen) IC tar),
Jen -(cotems Ft +1 Loan O-Ton! —
JE ola PUE Cafes) + (D-LCoten)s PF
Thelaterfonn(-)-[Onden)s Y rapidyaoemizesta(+)-an(-)-(Co(es)a7”* dueto tb adion
of small amount of ethylenediamine and CoCl 50. The aber products of the electron transfer
reaction is racemic mixture ofthe santos of C(e)s The (isomer ofthe ney formed
oft compleis precipita leaving (ise ine oie gor, which egin undergoes electron
transfer with [Co(en); ]** and again a racemic mixture uf [Oofem);]°* is obtained, the (+)-isomer of
whi again precipitates leaving (-) some inthe solution. In is process al ofthe (-}enaniomer
txiginally preset ate converted into the (+)-caniome. Aleraively if trate used instead of
arte a stating materi ll ofthe (amie canbe converted into (enantiomer. In is
process the yield is approximately 75%.
Synthesis of [Cr(bpy) a(H20)2]** or [Cr(phen)2(H20)21%*
‘lectrochemical eduction offCxpter)s}™* any} in aqueous solution leads ultimately
to the production of (Cr(phen)2(H20}21°* and (pp (H20)2 D.
ea
eu wn
RE)
vee U:
wi Ny
Ape,
Ein =009Y
In the this reaction, the [Cx(phen)s À formed is labile1o substitution and one o-phenanthroline
Higand is replaced by two water molecules and (Crphen)a(4120),1* is formed. This ion undergoes
electron transfer with (Cr(phen)s ** which is presuming to be still present to produce the final product,
TCxpben)2(4120)2 1”.
BEER TERN
Be
se
B
ICKAA) PT +210 | [CHAR (HO) + AA
[CHAO 7" CP" ET [OAA)2(H2O)27* HEC?
where AA is either o-phen or bpy.
Inhas been experimentally observed hat seme selatvely ne substance may enter int sscinin
suc way either to dire he eatonst different poductorto catalyze the reaction
Delepine has studied Rhodiumfül) complexes of amine ligands io aqueous and waterethanal
solutions, Delepine hs observed that pyridine recs with No RECI] in aquoous slain to give
{Rhy sCls} This compound is insoluble. Therefore, the reaction stops at ths stage and futher
substitution of a chloride by fourth molecule of pyridine to give [Rixpy)4Cl ]° becomes difficult and
requires lengthy reflux, To overcome this difficulty, Delepine has added ethanol with the expectation
‘that the complex {Rh(py);Cis Jbecomes soluble with the formation of [Rixpy)¿Cl 3* . In this reaction,
‘ethanol as a solvent behaves as a catalyst and diverts the reaction to form {Rhipy) <Cl2]* rather than
TRh(py)3Cl ] complex. As à result of addition of ethanol, the reaction between Nas{RhCle] and
ppidime in squeous-chanol solution prosets immediately and qualitatively obtain the crystals of
{RH(s)4Cl product at room temperature without formation of another intermediate.
aces hin
agency LE hi
me comes
SY 5 a
“ep mle
mo
a
Ch ho)
‘The mechanism and kinetics of the.abovereaction are quite similar to that for the PHII)-PKIV) redox
reaction discussed erie. The fist sep involves he edition of RI) to RD) by han. Ba e
species in which RI) is produced isnot ksown. Although, it is observed that [Rhipy)a]* is
finned rpily as pytiine is used in excess. Th ion are now set forthe formation of
[Rhipy)aCl2]* by a mechanism indentical 10 a PUIN-PUIV) two electron transfer reaction. It is
experimentally observed that [RKC] does or involved in this mechanism, The addon of
‘ehtanol to the aqueous solution leads to the formation of [Rh(py)aCl2J* not by solubilizing
{HCl Joutby athe ating ea ring agent
IRMHZOJCISP* +C¿HSOH — Riff) complex +CH,CHO
Ro spy Ri"
OMe y mr
mes Ed
m AS AV
¡non «IAN OJO emo Se i 7 ,
ax lea aha
Samy‘ NOS
a7] Na a/a
% Oy
mp ey
ml ol o
— maraca | San | ramo | PL
ae MON | APN | u 7 NT
a a
Other RMI) compounds can lso be prepared by the same technique, but the nature fie produc
<epends on tie nature ofigands involved andthe ation conditions. For example, ven inthe presence
‘of ethanol, [RHSCN)6 3° reacts with pyridine to give only [Rh(py) 3 (SCN); where SCN is bonded
to Rh through S:stom. In his ection ans-[RKpy)4 (SCAN 1° fon does not for because ofthe
ste hindrance between prin and SCN” and therefore, four pyridine ligands can no ie Pat ina
plane about RUI), instead the pyridine ligands amange as four bladed propeller about RACH), Since
M-SCNiinkageisdeat [NS | ‚ter wilberepuison between thebentSCN”lganéand
fe non-planr pyridine ligands,
PHOTOCHEMICAL REACTIONS,
If a transition metal complex absubs light radiations and goes in an excited site its redox
properties may change drasicaly. The complex in ts excited sate may undergo several kindof ney
transfer, out of which luminescence is most stnight forward. In this process light is remit asthe
cited state returns tothe ground sae (rade proces). Altematively, energy may be converted to
vibrational energy and dessipatd thermal othe environment a the complex eus t the ound
state (internal conversion). An important nd widely studied complex inthis aca is(RAp)* on
This complex on shows an intense metal to ligand charge transfer absorption band at 492 rm.
‘Aosorption ofa photon at this wavelength cause a transfer of en electron rom the highest occupied
rlecular orbital (HOMO), setoFRH() he west unocepied molecular obial (LUMO) ie, io
empty orbital of one ofthe ppt ligands abbreviated as bpy o give 2 singlet comple with
«tecno oniguraio 1, This tantin spin allowed andthe rsuling complex can be
described as{Ru™ (bpy) (opy” +. This complex undergoes rapid inersystem crossing without light
‘emission to give the loner energy and relatively long lived triplet state complex Ru (bp bp JD
‘eon stor (Sgt saa)
Se eins um
Eat
AAN: Ce sa)
ER
Guten LEE, on ZEN. rat
[2573
The hoe created a trance enhances its electro auracting ai nd as rs is
cation in excited state bolas as mach eter oxidzing agent as compared to is ground se.
Furthemore, th aval ofanclctonin ota ligand (bp) makes the excited sate ation much
biter reducing agent as compared 1 the round sate ation.
m
From Fig. 7.32, itis seca that *(Ru(bpy)2 (bpy™)}* is a better oxidizing agent than ground state,
[Ru(bos)3]?* by (084+ 1.28) =2.12 volts and beter reducing agent by (0.86 V+ 1.26 V)=2.12 volts
‘One set of photochemical edox runs:
(Resp Ra RANES
Ra RUN — Rap HR
Some complexes canbe esc y the tansitins and enhance the rte of ubstuion actions
In these complexes a lern excited fe tng et ty st (in octahedral complexes) nd nase
the eb ofcomplees seins lon density fn orbital increas the Mo nd gh
and weakened the ML bond. Pho‘osobitiuon rections of complexes sich 25 (CHNH)sX0",
LCNH3 Da X 2 J' and [CN ) CA have been widely studied,
mes Ed
m AS AV
¡non «IAN OJO emo Se i 7 ,
ax lea aha
Samy‘ NOS
a7] Na a/a
% Oy
mp ey
ml ol o
— maraca | San | ramo | PL
ae MON | APN | u 7 NT
a a
Other RMI) compounds can lso be prepared by the same technique, but the nature fie produc
<epends on tie nature ofigands involved andthe ation conditions. For example, ven inthe presence
‘of ethanol, [RHSCN)6 3° reacts with pyridine to give only [Rh(py) 3 (SCN); where SCN is bonded
to Rh through S:stom. In his ection ans-[RKpy)4 (SCAN 1° fon does not for because ofthe
ste hindrance between prin and SCN” and therefore, four pyridine ligands can no ie Pat ina
plane about RUI), instead the pyridine ligands amange as four bladed propeller about RACH), Since
M-SCNiinkageisdeat [NS | ‚ter wilberepuison between thebentSCN”lganéand
fe non-planr pyridine ligands,
PHOTOCHEMICAL REACTIONS,
If a transition metal complex absubs light radiations and goes in an excited site its redox
properties may change drasicaly. The complex in ts excited sate may undergo several kindof ney
transfer, out of which luminescence is most stnight forward. In this process light is remit asthe
cited state returns tothe ground sae (rade proces). Altematively, energy may be converted to
vibrational energy and dessipatd thermal othe environment a the complex eus t the ound
state (internal conversion). An important nd widely studied complex inthis aca is(RAp)* on
This complex on shows an intense metal to ligand charge transfer absorption band at 492 rm.
‘Aosorption ofa photon at this wavelength cause a transfer of en electron rom the highest occupied
rlecular orbital (HOMO), setoFRH() he west unocepied molecular obial (LUMO) ie, io
empty orbital of one ofthe ppt ligands abbreviated as bpy o give 2 singlet comple with
«tecno oniguraio 1, This tantin spin allowed andthe rsuling complex can be
described as{Ru™ (bpy) (opy” +. This complex undergoes rapid inersystem crossing without light
‘emission to give the loner energy and relatively long lived triplet state complex Ru (bp bp JD
‘eon stor (Sgt saa)
Se eins um
Eat
AAN: Ce sa)
ER
Guten LEE, on ZEN. rat
[2573
The hoe created a trance enhances its electro auracting ai nd as rs is
cation in excited state bolas as mach eter oxidzing agent as compared to is ground se.
Furthemore, th aval ofanclctonin ota ligand (bp) makes the excited sate ation much
biter reducing agent as compared 1 the round sate ation.
m
From Fig. 7.32, itis seca that *(Ru(bpy)2 (bpy™)}* is a better oxidizing agent than ground state,
[Ru(bos)3]?* by (084+ 1.28) =2.12 volts and beter reducing agent by (0.86 V+ 1.26 V)=2.12 volts
‘One set of photochemical edox runs:
(Resp Ra RANES
Ra RUN — Rap HR
Some complexes canbe esc y the tansitins and enhance the rte of ubstuion actions
In these complexes a lern excited fe tng et ty st (in octahedral complexes) nd nase
the eb ofcomplees seins lon density fn orbital increas the Mo nd gh
and weakened the ML bond. Pho‘osobitiuon rections of complexes sich 25 (CHNH)sX0",
LCNH3 Da X 2 J' and [CN ) CA have been widely studied,
Fitl in the Blanks
er
2. sable than (NICE). 4
1. (Ouen); is ….
2. The complex of Cu* is ... Stable than the complex of Za with same ligand.
3. [cs] ner han [RH(CN) 5]
à a
3. Inclecrontanstereacion, econ anse occur rom n* ri ofihereducantio n*orialof
oxidant, The reaction proceed by ………. mechanism.
6. Therute of electron tansfoin(CO(NILs )6)?*/[Co(NHa)6]”" systems
[FACH SI" FOND D system.
sve hat of
fans. Less 2, more
3. less 4, second
5. outer spre 6. slower}
Objective Gusstiong
1. The fina product containing chromium in the reaction between [Co(NH. )sC1]?*,[CHH30) 1°,
HO" is:
QG HO), CO“
EC" (COS,
2. Thectromium (UD paies formed soon after elecwon trans been CI and CHL 0} is:
DIE Wea} SC" BACH
aa @CHH10); CH
3. Electron are from F(Hs0)3* to Fo!K¿0)3* is key o occur via
(a) ¿dc (0) inner sphere electron raster
sn! (&) outer sphere electron transfer
4 (COCIONH Js)” + (LOG —>(Co(H20XNH3)5]" +(CxC1H:0)5]*
The coc saements regarding the above reactions thal
Hole outer ple mechanism
40) I follows inner-sphere mechanism with NH; acting as the bridging ligand
(6) Hai inner spero mechanism with I” acing athe bridgingligund,
AA) is ot an lecron transe action
$. The most suitable route to prepare the transe isomer of[PICI (NH; (PPh is:
m
a
48) (PICL¿]” with PPh followed by reaction with NH
(0)[PICI¿]?" with NH followed by reaction with PPh
OPEN: )¢]?* with HCl followed by reaction with PPh
COPINE) with PPh followed by reaction with HCH
rate of exchange of cyanide ligands in the complexes: (UNI(CNDA 1, GEMaCN)6 1"
GED" MON low he or a ae
QE o T°
ori Bern
7. Coordinated water molecules of a C4(I1} complexes can be successively replaced by Br” finally:
result [CBr ah process, the fourth equilibrium constant is observe tobe higher th
the hid one, esse
6) quil constant for he last step i always the highest
Aie molecules HO are elas during the fur tp
(6) the qu pes octal
(8) an anion (Br”) replace’ a neutral (H10) molecule from the coordination sphere
[Ehe CORRECT statement regarding the thermodynamic stability and kinetic reactivity of met
|e complet: —”
(a) More stable complexes are less reactive
(0) There exists a dependence on the bulkiness of the ligand
46) There exists no direct relation between these two phenomenon 7
£d) There exists a dependence on the size of the metal ion
The CORRECT oder e at exchange of water molecules betwen the colon sphe
OS
Y
Jan the bis:
ace cal cc ene rit cart << ce" +
> Wen ecrit <A (or < Cr < APY NEY Gen do
10 Ponsider the reactions:
( Argenttizoye}® +(COCKNHs Js À > COQ) (HO +(0:CI(H¿0)5 +
LPC HMM" (FACE HMC"
Which one ofthe following i the rec statement? 4e ot
(i Both involve an inner sphere mechanism
Bot vole an outer sphere mechanism
Gi) Reaction | fellows one spere and reaction 2 fllows ote sphere mechanism
(69) React fllows outer spec and reaction 2 follows ine pete mechanism,
@i wi
owe @ iti
11, Designate the following complexes X, Y and Z as inert-or labile:
LAC 37", XIV), Z = CCP GA
er
2. sable than (NICE). 4
1. (Ouen); is ….
2. The complex of Cu* is ... Stable than the complex of Za with same ligand.
3. [cs] ner han [RH(CN) 5]
à a
3. Inclecrontanstereacion, econ anse occur rom n* ri ofihereducantio n*orialof
oxidant, The reaction proceed by ………. mechanism.
6. Therute of electron tansfoin(CO(NILs )6)?*/[Co(NHa)6]”" systems
[FACH SI" FOND D system.
sve hat of
fans. Less 2, more
3. less 4, second
5. outer spre 6. slower}
Objective Gusstiong
1. The fina product containing chromium in the reaction between [Co(NH. )sC1]?*,[CHH30) 1°,
HO" is:
QG HO), CO“
EC" (COS,
2. Thectromium (UD paies formed soon after elecwon trans been CI and CHL 0} is:
DIE Wea} SC" BACH
aa @CHH10); CH
3. Electron are from F(Hs0)3* to Fo!K¿0)3* is key o occur via
(a) ¿dc (0) inner sphere electron raster
sn! (&) outer sphere electron transfer
4 (COCIONH Js)” + (LOG —>(Co(H20XNH3)5]" +(CxC1H:0)5]*
The coc saements regarding the above reactions thal
Hole outer ple mechanism
40) I follows inner-sphere mechanism with NH; acting as the bridging ligand
(6) Hai inner spero mechanism with I” acing athe bridgingligund,
AA) is ot an lecron transe action
$. The most suitable route to prepare the transe isomer of[PICI (NH; (PPh is:
m
a
48) (PICL¿]” with PPh followed by reaction with NH
(0)[PICI¿]?" with NH followed by reaction with PPh
OPEN: )¢]?* with HCl followed by reaction with PPh
COPINE) with PPh followed by reaction with HCH
rate of exchange of cyanide ligands in the complexes: (UNI(CNDA 1, GEMaCN)6 1"
GED" MON low he or a ae
QE o T°
ori Bern
7. Coordinated water molecules of a C4(I1} complexes can be successively replaced by Br” finally:
result [CBr ah process, the fourth equilibrium constant is observe tobe higher th
the hid one, esse
6) quil constant for he last step i always the highest
Aie molecules HO are elas during the fur tp
(6) the qu pes octal
(8) an anion (Br”) replace’ a neutral (H10) molecule from the coordination sphere
[Ehe CORRECT statement regarding the thermodynamic stability and kinetic reactivity of met
|e complet: —”
(a) More stable complexes are less reactive
(0) There exists a dependence on the bulkiness of the ligand
46) There exists no direct relation between these two phenomenon 7
£d) There exists a dependence on the size of the metal ion
The CORRECT oder e at exchange of water molecules betwen the colon sphe
OS
Y
Jan the bis:
ace cal cc ene rit cart << ce" +
> Wen ecrit <A (or < Cr < APY NEY Gen do
10 Ponsider the reactions:
( Argenttizoye}® +(COCKNHs Js À > COQ) (HO +(0:CI(H¿0)5 +
LPC HMM" (FACE HMC"
Which one ofthe following i the rec statement? 4e ot
(i Both involve an inner sphere mechanism
Bot vole an outer sphere mechanism
Gi) Reaction | fellows one spere and reaction 2 fllows ote sphere mechanism
(69) React fllows outer spec and reaction 2 follows ine pete mechanism,
@i wi
owe @ iti
11, Designate the following complexes X, Y and Z as inert-or labile:
LAC 37", XIV), Z = CCP GA
RIAS an Ron Michnik ie NET
U Xund Yareiner Zistable (0) Xord Za lab Yisinert
(e) Xis ine; YandZurelabile (8) Xi ble Y and Z are rn.
12, Which one of the following electronic configuation gives kinetically inert octahedal
complexes?
CITES CEE
one CPE
13. Reaction of[COCI(NH3)5]** by Cr?*(ag) leads to the formation [CHCHH2O)s LP . This is an
example of: a
(o) oterplere redox reaction (0) nner spere edo recon
(6) acid hydrolysis reaction (@) base hydrolysis reaction a
14. The substituionally ineryeomplex ion amongst be following is ord
ice AS A -
COUT PEO,"
a square pyramidal intermediate :
pein bases intermediate” ES
(© peragnal bipyramidal intermediate
(a fice capped acaba intermediate
16 bichon ofthe pis of following statements bos retin off COCs )s* by CH) is
Tet?
() Reactant [CoCIQNHs )s|?* has non-abile coordination sphere
Ci) Recon process by outer sphere mechani
Gi) Reset (CCI) has labile cordinatin spice |
2 Gu) Region proces by inner here echan,
© mat) (and Gd 3
(e) Gi) and (8) Gi) and iv),
17. cis-and trans- complexes of the type [PLA 2 X are distinguished by:
(a) chromyl chloride test (0) cacbylamino test
(© Kunakov test > CES
Coser two redox pain +
U aran CI
“Therate of acceleration in going from a ouer- sphere toa innerphere mechanism is lower fr (1)
‘ative to (2). is corre explanation is
(9) HOMOYLUMO area and respectively.
(©) HOMO/LUMO area” and x" respectively
à
{9 HOMOLUMO are x ando respectively.
(6 ROMO/LUMO are x and x" respectively
weg lung pasoo
(NH )s]** and [Cr(OH )6 JF [CO(NIES)5(OHz)P* end [OOH Jo +
CON: Js" and (Cr(OH: )6 à [Col(NH 5 F* and [CrOH2 6)?"
The let anse ate willbe fastestn the pair
(0) [CoF(NH3)5]?* and[CHOH2)6
OICHNH;)s OH) and [CHOH2)6 1
(Co¢NHs)6}* snd {CH(OH 6 Po ad
ON ana HOH) EA
faro statement about base hydrolysis {COQ CP is:
(a) sa fit order section
A The rate detemining step involves the dissociation of chloride in [Co(NH ) (NH ICI
(6) Theates independent ofthe concentration ofthe base
¿Y The rate determining step involves te ain of proto om [Co(MII CH" Ya y,
1/ For ie following outer sphere electron transfer reactions.
(Co(tts)gT* +10" NA)" (CON) +10" AH)"
[RUNELZ)6P* (Ru (NH3)5]°* —+ (RUN) Je +(Ru” (NE)
“The rate constants are 10° MIS"! and 8.2x 102 MS! respectively. This difference in the rate
constants duet:
(4) a change from high spin to low spin in Co* and high spin to low spin in Ru"
(6) a change from high spin to low spin in Co* and low spin to high spin Ru*
(ey change ram low spin o high pin in Co andthe low spin state remains unchanged in Ru“
(change om low spin to high spin in Co and high sin to low spi in Ru
22, Which one ofthe following complexes sKneticaly nern a soon?
ICH WI)“
OICOHO)T" Ja NICH)?"
® ie sbsittion reaction of {Ca(CN) CH" OH to give [CA(CID5OH]” in comparison to
hat {o(NHts)sCl]* to give (Co(NH) 0H)" is
ow and trate depends only on{OKCN SCH"
(0) fastand the rate depends only on (CofCN) C1}
(©) slow and the rate depends on [Co(CN)sCH?" and OHT
{@ fast and the rate depends on {Co(CN)sCH”” and OH”
U Xund Yareiner Zistable (0) Xord Za lab Yisinert
(e) Xis ine; YandZurelabile (8) Xi ble Y and Z are rn.
12, Which one of the following electronic configuation gives kinetically inert octahedal
complexes?
CITES CEE
one CPE
13. Reaction of[COCI(NH3)5]** by Cr?*(ag) leads to the formation [CHCHH2O)s LP . This is an
example of: a
(o) oterplere redox reaction (0) nner spere edo recon
(6) acid hydrolysis reaction (@) base hydrolysis reaction a
14. The substituionally ineryeomplex ion amongst be following is ord
ice AS A -
COUT PEO,"
a square pyramidal intermediate :
pein bases intermediate” ES
(© peragnal bipyramidal intermediate
(a fice capped acaba intermediate
16 bichon ofthe pis of following statements bos retin off COCs )s* by CH) is
Tet?
() Reactant [CoCIQNHs )s|?* has non-abile coordination sphere
Ci) Recon process by outer sphere mechani
Gi) Reset (CCI) has labile cordinatin spice |
2 Gu) Region proces by inner here echan,
© mat) (and Gd 3
(e) Gi) and (8) Gi) and iv),
17. cis-and trans- complexes of the type [PLA 2 X are distinguished by:
(a) chromyl chloride test (0) cacbylamino test
(© Kunakov test > CES
Coser two redox pain +
U aran CI
“Therate of acceleration in going from a ouer- sphere toa innerphere mechanism is lower fr (1)
‘ative to (2). is corre explanation is
(9) HOMOYLUMO area and respectively.
(©) HOMO/LUMO area” and x" respectively
à
{9 HOMOLUMO are x ando respectively.
(6 ROMO/LUMO are x and x" respectively
weg lung pasoo
(NH )s]** and [Cr(OH )6 JF [CO(NIES)5(OHz)P* end [OOH Jo +
CON: Js" and (Cr(OH: )6 à [Col(NH 5 F* and [CrOH2 6)?"
The let anse ate willbe fastestn the pair
(0) [CoF(NH3)5]?* and[CHOH2)6
OICHNH;)s OH) and [CHOH2)6 1
(Co¢NHs)6}* snd {CH(OH 6 Po ad
ON ana HOH) EA
faro statement about base hydrolysis {COQ CP is:
(a) sa fit order section
A The rate detemining step involves the dissociation of chloride in [Co(NH ) (NH ICI
(6) Theates independent ofthe concentration ofthe base
¿Y The rate determining step involves te ain of proto om [Co(MII CH" Ya y,
1/ For ie following outer sphere electron transfer reactions.
(Co(tts)gT* +10" NA)" (CON) +10" AH)"
[RUNELZ)6P* (Ru (NH3)5]°* —+ (RUN) Je +(Ru” (NE)
“The rate constants are 10° MIS"! and 8.2x 102 MS! respectively. This difference in the rate
constants duet:
(4) a change from high spin to low spin in Co* and high spin to low spin in Ru"
(6) a change from high spin to low spin in Co* and low spin to high spin Ru*
(ey change ram low spin o high pin in Co andthe low spin state remains unchanged in Ru“
(change om low spin to high spin in Co and high sin to low spi in Ru
22, Which one ofthe following complexes sKneticaly nern a soon?
ICH WI)“
OICOHO)T" Ja NICH)?"
® ie sbsittion reaction of {Ca(CN) CH" OH to give [CA(CID5OH]” in comparison to
hat {o(NHts)sCl]* to give (Co(NH) 0H)" is
ow and trate depends only on{OKCN SCH"
(0) fastand the rate depends only on (CofCN) C1}
(©) slow and the rate depends on [Co(CN)sCH?" and OHT
{@ fast and the rate depends on {Co(CN)sCH”” and OH”
eae EE RCE SNC AMS a Reais
34. Using ya feld theory, determine the typeof orbitals) which wil have the lowest nee in 3. Amange the following complexes in he increasing order of inertness:
complex shown below. Based on the above, dtemine the comparative rates of reduction ofthe ECON) GP, (Mn (CHENE [COC
f0(V) to MA(IV) versus Mn) to Mac) sates
4. What is rans- effect? What products obtained when [PICLa]” is treated with
(D Ny followed by R3P,
Gi) R5P followed by NHS?
5. Square plana complexes ace generally bile Explain.
For ovins gee extn,
(8) (dg) MAY) o MV) isslower than MoV) © MAI) + A EEE fous oyg * +CHERO)SCH?* + NE
(0) do, dyes dar Ma(¥) to MafIV) is slower than MA(IV) to MI) rate constant increases in the oer X" <F”, CI", Br“, 17. Explai Also give te mechanism
(Ga da, MoV) to Mo) fase than MoV) to M) of the above zehn.
en ann ZF: Give he echan ofthe flowing ction:
LODEL +HRUNES SI?" — (CONEA) 7 + (RUNES 6
(Jue da ac FO, ESO a hin NO Mer a ib cc an he WARY
yellow, colourless, red and again colores solutions due tothe respective formation of:
GIF 0);CU, {Fett20)5(PO4}, (FlH0)s(SCNDI*,[Fe(H20)s EP len para tat ee ee
@)IFH20); CIO)", [Fe(120)s(P04)), FelH0)s (SCH, [Fe(H20)s FI?" u ee à .
QFAB:0)s CD”, [Fe(H120)6]*", (FelH30)5 (SCH, [Fe(H20)5 FI" (Co(en)s 1" +1Cole)a]'* — [Cofen)5]°* + [Cofen)2}”*
48) [Fe(H20)sC?*,, {Fe(H:0)(POg)}, [FofH¿O)s (SCA, FRELHO),(SCHIFI" E A of Be lees een
e OH moult roo? Esad” eden cer
(HD) DMROH:)6 }* 5 GD (Fe(OH) 6}*, (1) (NOH) 6 *, follows an order: ~
For each of the following electron transfer reaction, speculate whether the mechanism is inner
E CNE ses . Sphere or outer sphere |
wo LONG one cano)" 4 (Cr(H20)s FI + SNE
CC — 110 HN”
. Let ec amour E (COJE. ext 0) (CS) SNE
Lo 10 1. 40 sm «0 10 A CO sfx CLOS)
fo Fo we re no Be Ko A. Give the mechanism of ccoo teaser reaction between [CoNHs}s(SCNIF* and
EQ D fh £8 80 20 no + GO) Case rate th andi cent rc
12. The second order cate constant for the reactions:
Con) +00) ES fotaoyg)?* +ONEG Cr O
ublective Quest
pe à 1380! a at »
1. Explain the term thermodynamic ad kinetic sabi Are hese to ers interrelated? plait 1) CP «cor E I" + NH + (HO):
giving examples.
ist and 6105 m5"! respectively. Explain te variation in ate constants by giving
2. Explain the tem abi
and inertness giving examples onthe basis of CFT.
34. Using ya feld theory, determine the typeof orbitals) which wil have the lowest nee in 3. Amange the following complexes in he increasing order of inertness:
complex shown below. Based on the above, dtemine the comparative rates of reduction ofthe ECON) GP, (Mn (CHENE [COC
f0(V) to MA(IV) versus Mn) to Mac) sates
4. What is rans- effect? What products obtained when [PICLa]” is treated with
(D Ny followed by R3P,
Gi) R5P followed by NHS?
5. Square plana complexes ace generally bile Explain.
For ovins gee extn,
(8) (dg) MAY) o MV) isslower than MoV) © MAI) + A EEE fous oyg * +CHERO)SCH?* + NE
(0) do, dyes dar Ma(¥) to MafIV) is slower than MA(IV) to MI) rate constant increases in the oer X" <F”, CI", Br“, 17. Explai Also give te mechanism
(Ga da, MoV) to Mo) fase than MoV) to M) of the above zehn.
en ann ZF: Give he echan ofthe flowing ction:
LODEL +HRUNES SI?" — (CONEA) 7 + (RUNES 6
(Jue da ac FO, ESO a hin NO Mer a ib cc an he WARY
yellow, colourless, red and again colores solutions due tothe respective formation of:
GIF 0);CU, {Fett20)5(PO4}, (FlH0)s(SCNDI*,[Fe(H20)s EP len para tat ee ee
@)IFH20); CIO)", [Fe(120)s(P04)), FelH0)s (SCH, [Fe(H20)s FI?" u ee à .
QFAB:0)s CD”, [Fe(H120)6]*", (FelH30)5 (SCH, [Fe(H20)5 FI" (Co(en)s 1" +1Cole)a]'* — [Cofen)5]°* + [Cofen)2}”*
48) [Fe(H20)sC?*,, {Fe(H:0)(POg)}, [FofH¿O)s (SCA, FRELHO),(SCHIFI" E A of Be lees een
e OH moult roo? Esad” eden cer
(HD) DMROH:)6 }* 5 GD (Fe(OH) 6}*, (1) (NOH) 6 *, follows an order: ~
For each of the following electron transfer reaction, speculate whether the mechanism is inner
E CNE ses . Sphere or outer sphere |
wo LONG one cano)" 4 (Cr(H20)s FI + SNE
CC — 110 HN”
. Let ec amour E (COJE. ext 0) (CS) SNE
Lo 10 1. 40 sm «0 10 A CO sfx CLOS)
fo Fo we re no Be Ko A. Give the mechanism of ccoo teaser reaction between [CoNHs}s(SCNIF* and
EQ D fh £8 80 20 no + GO) Case rate th andi cent rc
12. The second order cate constant for the reactions:
Con) +00) ES fotaoyg)?* +ONEG Cr O
ublective Quest
pe à 1380! a at »
1. Explain the term thermodynamic ad kinetic sabi Are hese to ers interrelated? plait 1) CP «cor E I" + NH + (HO):
giving examples.
ist and 6105 m5"! respectively. Explain te variation in ate constants by giving
2. Explain the tem abi
and inertness giving examples onthe basis of CFT.
GL Ss PEON
13. Anyhdrous CrCl dissolves mre rapidly ina ditt solution of Cel than in pure water. Esplin
14. The formation of Cu?" complexes with ethylenediamine exhibit the equi constants
fog Ki = 1050, log; = and log Ky =-1.0. Explain the lower valaof Ks an A.
45. The successive smbiity constants for the species formed in aqueous solitons when
ethylenedismine reacts wis NI) ar as follows:
log Kj ~15 fog = 64nd log K3 = 44
Caleuite value of,
16. When the pystin is added to an aqueous solution of NagRiCls, the reaction stops at
[RMpy) Ci bat on din a small amount of ethanol, quantitative Formation of (Rp)
oceurs. Explain sb giving stable mechanism
17. Explsin he importaace of bridging groop in nner sphere mechanism Explain the allowing dat
‘when bridging roo X is change as follows in he reaction of [CoN )s XI" with,
i i if?
ll
x= OCH 00-0 0-00
|
CA
Kristy 72 035 96x10
18, Explain eat enhancement forthe following reaction pars
ALO)" +{FAHO) 40m 5
{Fe{phen)s ]?* +[Fe(phen) 33° 30x10? mis
RUHE" NS 82x10 mts
Ra(ptea)s + + (Rafa a] 107 ms
1.
u.
References
. Coordination compounds, Bonding, Structure and Nomenclature, Ramanee D. Wjesken,
. Chemistry ofthe elements, NN. Green Wood and A, Bamshaw, Second edition,
. Advanced Inorganic Chemistry, F. Albert Cotton, Geoffrey A. Murillo, Manfred Bockmaan, Sth
esti,
organic chemistry, Gay Wullberg.
5. Inorganic chemistry, AG, Shape, Third edition,
. Chemistry, Me Mary and Fey, Second edition.
7. Chemisty, Raymond Chang, Eight edition, Tats McGraw-Hill
. Descriptive inorganic Chemisty, Geoff Rayner-Canham,
2,
1
14
15.
16
1.
‘Concise norganic Chemisny, LD Le, Fifth edition.
ins Overton, Fifth edi.
Physical Chemisty, Peter Atkins, Julio De Paula, th edition,
Inorgac chemistry, Principles of Stuctures and Reactivity, James E. Huey, Elen A. Keites,
Richard L. Keiter, Ohi K. Mei.
organi and Solid-state Chemistry, Glen E. Rodger.
Physical Methods in Inorganic Chemistry, Russell S. Drago, 1965.
Basie Inorganic Chemisty, RA. Cotoo, G, Wilkinson, Paul L. Gaur, Tird Edition 2003,
‘Modern Inorganic Chemistry, Wiliam L. Jolly, Second edition.
Fundamentals of Molecular Specroscopy, Colin N. Banwell, Elaine M. MeCash Fouth ein,
Inorganic Chemistry, CoereneE. Housecrat and A.G, Sharpe, Second edition.
13. Anyhdrous CrCl dissolves mre rapidly ina ditt solution of Cel than in pure water. Esplin
14. The formation of Cu?" complexes with ethylenediamine exhibit the equi constants
fog Ki = 1050, log; = and log Ky =-1.0. Explain the lower valaof Ks an A.
45. The successive smbiity constants for the species formed in aqueous solitons when
ethylenedismine reacts wis NI) ar as follows:
log Kj ~15 fog = 64nd log K3 = 44
Caleuite value of,
16. When the pystin is added to an aqueous solution of NagRiCls, the reaction stops at
[RMpy) Ci bat on din a small amount of ethanol, quantitative Formation of (Rp)
oceurs. Explain sb giving stable mechanism
17. Explsin he importaace of bridging groop in nner sphere mechanism Explain the allowing dat
‘when bridging roo X is change as follows in he reaction of [CoN )s XI" with,
i i if?
ll
x= OCH 00-0 0-00
|
CA
Kristy 72 035 96x10
18, Explain eat enhancement forthe following reaction pars
ALO)" +{FAHO) 40m 5
{Fe{phen)s ]?* +[Fe(phen) 33° 30x10? mis
RUHE" NS 82x10 mts
Ra(ptea)s + + (Rafa a] 107 ms
1.
u.
References
. Coordination compounds, Bonding, Structure and Nomenclature, Ramanee D. Wjesken,
. Chemistry ofthe elements, NN. Green Wood and A, Bamshaw, Second edition,
. Advanced Inorganic Chemistry, F. Albert Cotton, Geoffrey A. Murillo, Manfred Bockmaan, Sth
esti,
organic chemistry, Gay Wullberg.
5. Inorganic chemistry, AG, Shape, Third edition,
. Chemistry, Me Mary and Fey, Second edition.
7. Chemisty, Raymond Chang, Eight edition, Tats McGraw-Hill
. Descriptive inorganic Chemisty, Geoff Rayner-Canham,
2,
1
14
15.
16
1.
‘Concise norganic Chemisny, LD Le, Fifth edition.
ins Overton, Fifth edi.
Physical Chemisty, Peter Atkins, Julio De Paula, th edition,
Inorgac chemistry, Principles of Stuctures and Reactivity, James E. Huey, Elen A. Keites,
Richard L. Keiter, Ohi K. Mei.
organi and Solid-state Chemistry, Glen E. Rodger.
Physical Methods in Inorganic Chemistry, Russell S. Drago, 1965.
Basie Inorganic Chemisty, RA. Cotoo, G, Wilkinson, Paul L. Gaur, Tird Edition 2003,
‘Modern Inorganic Chemistry, Wiliam L. Jolly, Second edition.
Fundamentals of Molecular Specroscopy, Colin N. Banwell, Elaine M. MeCash Fouth ein,
Inorganic Chemistry, CoereneE. Housecrat and A.G, Sharpe, Second edition.
18. Inrganio Chemistry, D.F. Shriver, P.W. Atkins, Third edition.
19. Concept and Models of Inorganic Chemistry, Bodie E. Douglas, DH. MeDaniel, John J.
Alexander, John Weley end Sons.
20, An Introduction to Inorganic Chemistry, Keih F. Purcell John C. Kot, 1980.
21, Mechanism of Inorganic Reaction, A study of metal complexe in solutions, Fred Basolo and
Ralph G. Pearson, 1973.
A + nr Ligand Charge Transfer (547)
Tania tipo (10 «Se el. Fene
+ Angular Momentum ofan Electron (5.4) Resctions (7.68)
«Application of CSE + Classe and metals (7.7)
lessees
c
+ Entialpy of Hydro of Transition Metal
fons (633)
+ Late Energy (4.34)
+ tonic Radi of Divalent Metal of 3-series
“Transition Elements (135)
+ Structure of Spine (437)
Normal Spin (437)
averse Spin (4.37)
Acid Hydrolysis (220)
Arion Reston (120)
Asiieromagaaic Substances (65)
Aguation Reaction (7.21)
Arts Colour Whee (5.1)
Bridging Ligand (1.17)
Base Hydlyis 7.23)
Beer Lambert Law (54)
Cassin of Ligands (1.10)
+ Monodentat Ligands (1.11)
+ oleate Ligands (1.12)
Chassifestion of Polydntate Ligands (1.12)
+ Bidet Ligands (1.12)
4 Tridente Ligands (114)
+ Teradentte Ligands (1.15)
1 Peniadentse Ligands (115)
+ Hexadentae Ligands (116)
‘Charge Tater spot.
+ IMCTG4)
+ MUCTOAS)
trance Transition (5.46)
+ Crystal Field Spin in
+ Octhedeal Complexes (4.15)
+ Tetabodral Completes (4.17)
+ Square Planar Compleses (431)
+ Crystal Field Splting Diagram for
+ Trigonal bipyramidal Complexes (452)
+ Square pyramidal Complex (452)
+ Pentagoral bipyramidal Complexes (452)
+ Crystal field stabilization energy in
+ Detabodal Complexes (622)
+ Tetahedal Conplees (425)
+ Gays Field Theory (4.13)
© Curie Law (64)
Cure Weiss Law (64)
2
Diem abs (6)
+ Dynamic in Tele Distortion (430)
E
+ Evidence fo Dison (S yt) Mestanisn
039
+ idee in aso of Asie Meli
04)
+ idee fr Men Land Corta Boa in.
Compleres 4:40)
+ Ecco Spin Resonance ESR) (440)
2 acer Magnetic Rooms (NDR) (4.40)
+ Neptune Elsa (6.40)
+ otr Quatre NQR)(4:40)
+ Evidence Fair of Wemer’s Ty (LT)
+ Besos Spa Angular Mom (55)
19. Concept and Models of Inorganic Chemistry, Bodie E. Douglas, DH. MeDaniel, John J.
Alexander, John Weley end Sons.
20, An Introduction to Inorganic Chemistry, Keih F. Purcell John C. Kot, 1980.
21, Mechanism of Inorganic Reaction, A study of metal complexe in solutions, Fred Basolo and
Ralph G. Pearson, 1973.
A + nr Ligand Charge Transfer (547)
Tania tipo (10 «Se el. Fene
+ Angular Momentum ofan Electron (5.4) Resctions (7.68)
«Application of CSE + Classe and metals (7.7)
lessees
c
+ Entialpy of Hydro of Transition Metal
fons (633)
+ Late Energy (4.34)
+ tonic Radi of Divalent Metal of 3-series
“Transition Elements (135)
+ Structure of Spine (437)
Normal Spin (437)
averse Spin (4.37)
Acid Hydrolysis (220)
Arion Reston (120)
Asiieromagaaic Substances (65)
Aguation Reaction (7.21)
Arts Colour Whee (5.1)
Bridging Ligand (1.17)
Base Hydlyis 7.23)
Beer Lambert Law (54)
Cassin of Ligands (1.10)
+ Monodentat Ligands (1.11)
+ oleate Ligands (1.12)
Chassifestion of Polydntate Ligands (1.12)
+ Bidet Ligands (1.12)
4 Tridente Ligands (114)
+ Teradentte Ligands (1.15)
1 Peniadentse Ligands (115)
+ Hexadentae Ligands (116)
‘Charge Tater spot.
+ IMCTG4)
+ MUCTOAS)
trance Transition (5.46)
+ Crystal Field Spin in
+ Octhedeal Complexes (4.15)
+ Tetabodral Completes (4.17)
+ Square Planar Compleses (431)
+ Crystal Field Splting Diagram for
+ Trigonal bipyramidal Complexes (452)
+ Square pyramidal Complex (452)
+ Pentagoral bipyramidal Complexes (452)
+ Crystal field stabilization energy in
+ Detabodal Complexes (622)
+ Tetahedal Conplees (425)
+ Gays Field Theory (4.13)
© Curie Law (64)
Cure Weiss Law (64)
2
Diem abs (6)
+ Dynamic in Tele Distortion (430)
E
+ Evidence fo Dison (S yt) Mestanisn
039
+ idee in aso of Asie Meli
04)
+ idee fr Men Land Corta Boa in.
Compleres 4:40)
+ Ecco Spin Resonance ESR) (440)
2 acer Magnetic Rooms (NDR) (4.40)
+ Neptune Elsa (6.40)
+ otr Quatre NQR)(4:40)
+ Evidence Fair of Wemer’s Ty (LT)
+ Besos Spa Angular Mom (55)
ESE
TERRA RNS
Flexidentate Ligands (1.17)
Affecting Stability of Complexes
+ Nature of the Central Meta ou (7.5)
+ Nature ofthe Ligands (7.8)
+ The Chelate Effect (7.8)
+ Macrocylic Effet (7.11)
9 Resomnce Effect (7.11)
+ Steric Effect o Steric Hindance (7.11)
‘+ Facil and Meridional Isomers (2.19)
Ferrimagnetie Substmces (6.5)
‘Ferromagnetic Substances (63)
G
T cemeie isaion 2.4)
+ Octet Complexs 217)
+ Square Planar Complexes (2.15)
+ Homo and role Complexes (1.20)
+ High Spin Couplers (421)
+ igh spin ow spin ain 611)
+ Hate somes (2-10)
a
+ bone 29)
Serra home (29)
+. Seoane (214) «-
Inner Sphere Média (1.5)
vins Wiliam ers (16)
Interpretes of Lab sod Teress of
Transition Mel Complees (1.16)
TUPACNorrclnze (1)
Inverse sil (437)
lure
+ Jahn-Teller Disonion (4.25)
+ Saticand Dynamic (4.30)
K
+ nee Sub: Lab anaes 712)
+ KunakovTet(733)
L
+ Lips)
+ aident (116)
+ Baiting QU)
+ Fiexidentate (1.17)
+ Macys (12
+ Ligand Field Troy (44)
+ Lindon.)
+ Liste omen 210)
+ Low Spin Comps (421)
M
À Mecheye ins (120)
+ Mechs of Sesion React ia Sure
Par Coples (242)
+ Magne Moment (66)
+ Magro Sup (62,66
+ Magni (61)
+ Mist (8)
+ Marsa Real (259
N
+ Naming of Bridged Polymucteas Complex (3.5)
+ Naming of Coiinton Cope. having
Cation sn Anon bats Cone kn)
+ Naming of Congo: corning He
Wer Melee)
Rang of Goma ones 1)
‘Naming of Optical Isomers (3.15)
Normal Spinels (4.37)
¿0
+ Opti or Minor ge cis 229)
© Optica Isomers in Square Ple Complexes
a2)
« Otal Angular Momentum (4)
+ Orbital Conibuion (69)
+ Outer Sphere Mean (46)
Pairing Energy (422)
Paramagneie Substances (65)
acceptor (4.48)
bonding in Otal Complexes (4.46)
donors (447)
Polymerization Ice (2.13)
Precipitation Reactions (1.16
Photochemical Reactions (7.72)
messe.
+ Recah Panmeles and Nephelaueic Series
6.2)
+ Reaction Profs for Disocaive, Associative
and Interchange Mostanisns (7.15)
+ Redox Rarions or Electron Transer Resctons
046)
+ Remote Attack (739)
s
+ Symmetizal and Uncyrumetieal Bidentate
Ligands (1.18)
+ Selection Rules
2 Laporte Selection (5.13)
2 Spin Selection (14)
© Spectrochemical Sees (420)
‘Spectroscopic Tes (59)
+ Subsittion Reston in Othodral Complexes
a
+ Sobslituien Reaction in Square Planar
Complexes (132)
+ Sterochemisry of Acid Catalyzed Substitution
Reactions (729)
+ Sidwick Concept of Coordinae Bon (18)
«Signa Boning in:
3 Tearabedral Compleses (649)
Square Planer Compleses (4.50)
Substitution Resctions witout being
Meta-Ligand Bond (728)
+ Spin-Orbial Coupling (57)
+ LS Coupling or Rush Saunders Coopling
67
+ 24 Coupling (5.8)
‘Tetagonal Distosion (425)
‘Tanabe Sugano Diagrams (547)
Term Symbols (53)
‘Thermodynamic Sab.)
Total Angular Momentim of Many Eleccon
Atoms (56)
+ Total Orbital Angular Momentua (5.6)
+ Total Spin Angular Moment (57)
+ Spin Orbit Coupling (5.7)
Trans Effect (735)
‘Theories of Trans Effet
+ Polarization theory (739)
2: bonding theory (741)
‘Two Electron Transfer (1.67)
Total Angular Momentum (5.6)
a
x
+ Valence Bod Ther (1)
w
Wemer's Thocry (12)
+ Water Exchange (7.19)
000
TERRA RNS
Flexidentate Ligands (1.17)
Affecting Stability of Complexes
+ Nature of the Central Meta ou (7.5)
+ Nature ofthe Ligands (7.8)
+ The Chelate Effect (7.8)
+ Macrocylic Effet (7.11)
9 Resomnce Effect (7.11)
+ Steric Effect o Steric Hindance (7.11)
‘+ Facil and Meridional Isomers (2.19)
Ferrimagnetie Substmces (6.5)
‘Ferromagnetic Substances (63)
G
T cemeie isaion 2.4)
+ Octet Complexs 217)
+ Square Planar Complexes (2.15)
+ Homo and role Complexes (1.20)
+ High Spin Couplers (421)
+ igh spin ow spin ain 611)
+ Hate somes (2-10)
a
+ bone 29)
Serra home (29)
+. Seoane (214) «-
Inner Sphere Média (1.5)
vins Wiliam ers (16)
Interpretes of Lab sod Teress of
Transition Mel Complees (1.16)
TUPACNorrclnze (1)
Inverse sil (437)
lure
+ Jahn-Teller Disonion (4.25)
+ Saticand Dynamic (4.30)
K
+ nee Sub: Lab anaes 712)
+ KunakovTet(733)
L
+ Lips)
+ aident (116)
+ Baiting QU)
+ Fiexidentate (1.17)
+ Macys (12
+ Ligand Field Troy (44)
+ Lindon.)
+ Liste omen 210)
+ Low Spin Comps (421)
M
À Mecheye ins (120)
+ Mechs of Sesion React ia Sure
Par Coples (242)
+ Magne Moment (66)
+ Magro Sup (62,66
+ Magni (61)
+ Mist (8)
+ Marsa Real (259
N
+ Naming of Bridged Polymucteas Complex (3.5)
+ Naming of Coiinton Cope. having
Cation sn Anon bats Cone kn)
+ Naming of Congo: corning He
Wer Melee)
Rang of Goma ones 1)
‘Naming of Optical Isomers (3.15)
Normal Spinels (4.37)
¿0
+ Opti or Minor ge cis 229)
© Optica Isomers in Square Ple Complexes
a2)
« Otal Angular Momentum (4)
+ Orbital Conibuion (69)
+ Outer Sphere Mean (46)
Pairing Energy (422)
Paramagneie Substances (65)
acceptor (4.48)
bonding in Otal Complexes (4.46)
donors (447)
Polymerization Ice (2.13)
Precipitation Reactions (1.16
Photochemical Reactions (7.72)
messe.
+ Recah Panmeles and Nephelaueic Series
6.2)
+ Reaction Profs for Disocaive, Associative
and Interchange Mostanisns (7.15)
+ Redox Rarions or Electron Transer Resctons
046)
+ Remote Attack (739)
s
+ Symmetizal and Uncyrumetieal Bidentate
Ligands (1.18)
+ Selection Rules
2 Laporte Selection (5.13)
2 Spin Selection (14)
© Spectrochemical Sees (420)
‘Spectroscopic Tes (59)
+ Subsittion Reston in Othodral Complexes
a
+ Sobslituien Reaction in Square Planar
Complexes (132)
+ Sterochemisry of Acid Catalyzed Substitution
Reactions (729)
+ Sidwick Concept of Coordinae Bon (18)
«Signa Boning in:
3 Tearabedral Compleses (649)
Square Planer Compleses (4.50)
Substitution Resctions witout being
Meta-Ligand Bond (728)
+ Spin-Orbial Coupling (57)
+ LS Coupling or Rush Saunders Coopling
67
+ 24 Coupling (5.8)
‘Tetagonal Distosion (425)
‘Tanabe Sugano Diagrams (547)
Term Symbols (53)
‘Thermodynamic Sab.)
Total Angular Momentim of Many Eleccon
Atoms (56)
+ Total Orbital Angular Momentua (5.6)
+ Total Spin Angular Moment (57)
+ Spin Orbit Coupling (5.7)
Trans Effect (735)
‘Theories of Trans Effet
+ Polarization theory (739)
2: bonding theory (741)
‘Two Electron Transfer (1.67)
Total Angular Momentum (5.6)
a
x
+ Valence Bod Ther (1)
w
Wemer's Thocry (12)
+ Water Exchange (7.19)
000
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