"The coordination complexes in which the central metal atom undergoes hybridisation by using -orbitals of the inner shell and -orbitals of the outer shells are called inner orbital complexes."
For example, complex is an inner orbital complex that takes into account its inner orbitals having hybridisation .
Spin of inner orbital complexes:
In inner orbital complexes, pairing occurs due to hybridisation.
Due to pairing, there are a lesser number of unpaired electrons or no unpaired electrons in these complexes.