Coordination Compounds 2 Question 3

####3. The complex ion that will lose its crystal field stabilisation energy upon oxidation of its metal to +3 state is

Ignore pairing energy

(a) [Co( phen )3]2+

(b) [Ni( phen )3]2+

(c) [Zn( phen )3]2+

(d) [Fe( phen )3]2+

(2019 Main, 12 April I)

Show Answer

Solution:

  1. Key Idea Crystal field splitting occurs due to the presence of ligands in a definite geometry. In octahedral complexes the energy of two, eg orbitals will increase by (0.6)Δo and that of three t2g will decrease by (0.4)Δ0.

The complex ion that will lose its crystal field stabilisation energy upon oxidation of its metal to +3 state is [Fe( phen )3]2+.

[Fe( phen )3]2+e[Fe( phen )3]3+

In [Fe( phen )3]2+, electronic configuration of Fe2+ is 3d64s0. Phenanthrene is a strong field symmetrical bidentate ligand. The splitting of orbital in Fe2+ is as follows:

CFSE =6×0.4Δo=2.4Δo.

The splitting of orbital and arrangement of electrons in Fe3+ is as follows :

CFSE =5×0.4Δo=2.0Δo

Fe2+ upon oxidation of its metal to +3 state lose its CFSE from 2.4Δo to 2.0Δo.



NCERT Chapter Video Solution

Dual Pane