Question

Why are cyano complexes more stable than ammine complexes?

Answer 1

Answer:

A spectrochemical series is a list of ligands ordered on ligand strength and a list of metal ions based on oxidation number, group and its identity.

I−<Br−<SCN−<Cl−<S2−<F−<OH−<C2O42−<H2O<NCS−<edta4−<NH3<en<CN−<CO

Ligands arranged on the left end of this spectrochemical series are generally regarded as weaker ligands and cannot cause forcible pairing of electrons within 3d level and thus form outer orbital octahedral complexes. On the other hand ligands lying at the right end are stronger ligands and form inner orbital octahedral complexes after forcible pairing of electrons within 3d level.

According to above passage CO is a stronger ligand than NH3. So, carbonyl complexes are more stable than ammine complexes.