Question

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 gives below:

• A. I and II only
• B. II, III and IV only
• C. II and IV only
• D. I, II and only

Answer 1

The correct option is C II and IV only

The metals in complexes $Fe(CO{)}_5$ and $Cr(CO{)}_6$ undergo $ds{p}^3$ and $d^{2}s{p}^3$ hybridization respectively. These complexes contain all paired electrons. Thus these complexes are inner orbital complexes and diamagnetic in nature.
The metal in $Ni(CO{)}_4$ undergo $s{p}^3$ hybridization. In this complex, all electrons are paired. Thus it is outer orbital diamagnetic complex.
The metal in $V(CO{)}_6$ undergo $d^{2}s{p}^3$ hybridization. This complex contains one unpaired electron. Thus it is inner orbital and diamagnetic in nature.