Question

The bond order between $Ni—C$ bond in $Ni(CO{)}_4$ is

• A. one
• B. two
• C. less than two
• D. more than two

Answer 1

Answer: (C)

$CO$ form synergistic $\pi$ back bonds with transition metals. It includes three components to give a partial triple bond. A $\sigma$ bond is formed by the overlapping of non-bonding $sp$-hybridised electron pair of $C$ with the blend of $d,s$ and $p$ orbitals of metal. Filled $d$ -orbitals of the metal also overlaps with a pair of $\pi$ anti-bonding orbitals of carbon of $CO$. To form such a bond, the oxidation state of metal atom must be lower than two