Why does Co2+ readily oxidise to Co3+ in complexes?

Asked by Navya Benny | 16th Dec, 2015, 04:44: PM

Expert Answer:

Co2+ ions readily gets oxidised to Co3+ ions because the crystal field stabilization energy of Co3+ ion with d6 configuration is more than Co2+ ion with a d7 configuration.

In presence of ligand the d-orbitals of metal get split up into two sets of orbitals that is t2g and eg. The half filled or fully filled t2g is more stable than other configurations. This is because it gives maximum amount of low energy of t2g orbitals. Lower the energy more is the stabilization.

Even air will oxidise Co2+ ions to Co3+ ions in the presence of cyanide ions or ammonia and the rresulting cobalt (III) complexes are much more stable than the corresponding cobalt (II) ions.

Answered by Hanisha Vyas | 17th Dec, 2015, 11:08: AM