REDOX REACTION : inner & outer sphere Complimentary & non-complimentary reaction

Introduction
Definition of Redox Reaction
Outer sphere mechanism
Inner sphere mechanism
Requirements of ISM
Complimentary reactions
Non-complimentary reaction

1. Name - SACHIN ROHIDAS KALE Std - Msc part 1 SEM - II ROLL NO . - 8044 Sub - Inorganic Chemistry PPT TopicS - Redox ReaCtion

2. CONTENT Introduction Definition of Redox Reaction Outer sphere mechanism Inner sphere mechanism Requirements of ISM Complimentary reactions Non-complimentary reaction

3. INTRODUCTION : Redox  (short for  red uction– ox idation reaction) (pronunciation:  /ˈ rɛdɒks /   redoks  or  /ˈ riːdɒks /   reedoks ) is a  chemical reaction  in which the  oxidation states  of atoms are changed. Any such reaction involves both a reduction process and a complementary oxidation process, two key concepts involved with  electron transfer  processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed; in general, redox reactions involve the transfer of  electrons  between  chemical species . The chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced.

4. Definition of redox reaction An oxidation reduction reaction is a any chemical reaction in which the oxidation number of molecule, atom or ion changes by gaining or losing an electron. ❶ [Cr(H2O) 6 ]²⁺+[ Ircl ]² [Cr(H2O)₆]³⁺+[ IrCl ₆]³ ❷ [Fe*(H2O)₆]²⁺+[Fe(H2O)₆]³⁺ [Fe*(H2O)₆]³⁺+[Fe(H2O)₆]²⁺

5. The outer sphere mechanism In this mechanism the electrons jumps across from the reductant to the oxidant the coordination sphere remain unaffected [Fe(CN)₆]⁴⁻+[Mo(CN)₈]³⁻ [Fe(CN)₆]³⁻+[MO(CN)₈]⁴⁻ Requirments for outer sphere mechanism. For easy electron transfer the reactant and oxidunt should have similar structures. For electron transfer to take place the energies of the participating electronic orbitals must be same and this is possible only when metal ligand bond length of the two reacting complexes are equal.

6. In this mechanism oxidant and reductant attach them selves to one another at same stage of the reaction. [Cr(H2O)₆]²⁺+[CO(NH₃) Cl ]²⁺ [(CH2O)₅ Cr----- Cl ----Co(NH₃)₅]⁴⁺ Bridged activated complex [CH2O)₅ CrCl ]²⁺[CO(NH₃)₅]²⁺ [Cr(II)―Cr(III)] [CO(III)―CO(II )] The Inner sphere mechanism .

7. In this mechanism a ligand is shared between the reductant and oxidant in their inner co-ordination sphere The attachment between oxidant and reductant occurs through a bonding ligands. One ligand of one reactant must substitutionally labile there for it should be capable of getting replace by a bridging ligand in an easy substitution process Requirements of ISM

8. COMPLEMENTARY REACTION There are some elements that have stable oxidation states which differ by two electrons In most of such cases it has been shown that two electron transfer takes place Eg - Pt (II)/ Pt (IV) Sn²⁺+ TI³⁺― Sn ⁴⁺+TI⁺¹ Sn²+Hg⁺― Sn ⁴⁺+Hg⁰

9. Non complimentary electron transfer reaction. In all electron transfer reaction considered so far the oxidant and the reductant have undergone change in oxidation state by the same number. Eg - Fe²⁺―Fe³⁺ Fe³―Fe²⁺ Such reactions are called Complementary reaction, However in the electron transfer reaction 2Fe²⁺+TI³⁺―2Fe³⁺+TI⁺

10. REFERENCE : P. Atkins, T. Overton, J. Rourke , M. Weller and F. Armstrong, Inorganic Chemistry, 5th Ed., Oxford University Press, 2010. F. Basalo and R. G. Pearson, Mechanism of Inorganic Reactions, 2nd Ed., Wiley, 1967.

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