Question

In metal carbonyls, there is synergic bonding interaction between metal and carbon monoxide.This leads to increase in strength of metal ligand bond and decrease in bond order of CO in carbonyl complex as compared to bond order in carbon monoxide.
Simple carbonyls are invariably spin-paired complexes except for vanadium metal.
Which amongst the following metal carbonyls are inner orbital complexes with diamagnetic property ?
(I)`Ni(CO)_4` , (II)`Fe(CO)_5` , (III)`V(CO)_6` , (IV)`Cr(CO)_6`
Select the correct answer from the codes given below :
A. I and II only
B. II, III and IV only
C. II and IV only
D. I,II and IV only

Answer 1

Correct Answer - C
The complex which uses (n-1)d orbital in the hybridisation is called as inner orbital complex.
`Ni(CO)_4-sp^3`, diamagnetic
`Fe(CO)_5-dsp^3`, diamagnetic
`V(CO)_6-d^2sp^3` paramagnetic with one unpaired electron
`Cr(CO)_6-d^2sp^3`, diamagnetic