Crystal Field Splitting parameter (Δ0) depends on.
(a) Strength of the ligands and
(b) Oxidation state of the metal.
(a) Strength of the ligands : Since strong field ligands like CN-, en, etc. approach closer to the central metal ion, it results in a large crystal field splitting and hence Δ0has higher values.
(b) Oxidation state of the metal : A metal ion with the higher positive charge draws the ligands closer to it which results in large separation of t2g and eg set of orbitals. The complexes involving metal ions with low oxidation state have low values of Δ0.
For example,
[Fe(NH3)6]3+ has higher Δ0 than [Fe(NH3)6]2+. H
