Question on Coordination Chemistry

All the octahedral complexes formed by Ni²⁺ are sp³d² hybridized and not d²sp³. Why?

Answer:

To form d²sp³ hybridisation the central metal atom must have two of its inner d-orbital vacant for hybridisation. Ni²⁺ is 3d⁸ and hence even if all the electrons in the 3d sub-shell get paired due to presence of strong field ligand, it will have only one of its inner d-orbital vacant. So, Ni²⁺ cannot form octahedral complexes with d²sp³ hybridisation.