EAN rule.pptx

EAN Rule

1. Effective Atomic Number (EAN)

2. What is EAN rule? The Sidgwick suggested that the Metal ion accept electron pair from Ligand until they achieves Inert gas configuration or Effective Atomic Number is called as E.A.N. Rule

3. Formula E.A.N. = ( Z – n ) + (2 X C.N.) Where, Z = atomic number of central metal n = charge on metal ion (number of electrons lost in metal ion formation ) C.N.= co-ordination number i.e. number of ligands attached to the metal

4. The complexes are Stable when the E.A.N calculations has atomic numbers of Inert gas configurations such as Ne (10), Ar (18), Kr (36), Xe (54), Ra (86 )

5. Examples 1) [Co(NH 3 ) 6 ] 3+ E.A.N. = Z – n + (2 X C.N.) Z = 27, n = 3 and C.N. = (2 X 6) = 12 E.A.N. = 27 – 3 + 12= 36 Atomic Number of Krypton (Kr) is 36 So, compound obeys E.A.N. rule, thus It is stable.

6. 2) [Ni(CO) 4 ] E.A.N. = Z – n + (2 X C.N.) Z = 28, n = 0 and C.N. = (2 X 4) = 08 E.A.N. = 28 – 0 + 8 = 36 Atomic Number of Krypton (Kr) is 36 , So, compound obeys E.A.N. rule, thus It is stable

7. 3) [ Fe(CN) 6 ] 3+ E.A.N. = Z – n + (2 X C.N.) Z = 26, n = 3 and C.N. = (2 X 6) = 12 E.A.N. = 26 – 3 + 12 = 35 Atomic Number of Krypton (Kr) is 36 , So, compound does not obeys E.A.N. rule, and thus It is unstable .

8. 4) [Pt(NH 3 ) 6 ] 4+ E.A.N. = Z – n + (2 X C.N.) Z = 78, n = 4 and C.N. = (2 X 6) = 12 E.A.N. = 78 – 4 + 12 = 86 Atomic Number of Radon (Ra) is 86 , So, compound obeys E.A.N. rule, thus It is stable

9. 5) [ PdCl 4 ] 2+ E.A.N. = Z – n + (2 X C.N.) Z = 46, n = 2 and C.N. = (2 X 4) = 08 E.A.N. = 46 – 2 + 8 = 52 Atomic Number of Xenon ( Xe ) is 54 So, compound does not obeys E.A.N. rule, and thus it is unstable

10. 6) [Ag(NH 3 ) 4 ] + E.A.N. = Z – n + (2 X C.N.) Z = 47, n = 1 and C.N. = (2 X 4) = 08 E.A.N. = 47 – 1 + 8 = 54 Atomic Number of Xenon ( Xe ) is 54 So, compound obeys E.A.N. rule, thus It is stable

11. Limitations 1) Many complexes are quite stable even though they does not obey E.A.N. rule. 2) The ligand donates electron pair and metal accept them. Due to this transfer of electrons, negative charge on metal ion is increases. This decreases the stability of complex. 3) The 2S 2 electron pair in NH 3 and H 2 O does not have bonding characters. 4) It does not gives geometry of complexes.

12. Merits 1) This theory can easily predict the co-ordination number of metal. 2) It explains the stability of complexes.