Question

What are inner d orbitals and outer d orbitals?

Answer 1

There are two types of hybridization in complex. inner orbital and outer orbital. 

In the inner d orbital: d2 sp3 hybridization is done
in the outer d orbital: sp3 d2 hybridization is done. 

Answer 2

Explanation:

The main difference between inner and outer orbital complexes is that the hybridization of the atomic orbitals of the central metal atom of inner orbital complex involves inner shell d orbitalswhereas the hybridization of the atomic orbitals of the central metal atom of outer orbital complex involves outermost shell d