Discuss the nature of bonding in metal carbonyls.

(N/A) The metal-carbon bonds in metal carbonyls have both $\sigma$ and $\pi$ characters.
$A$ $\sigma$ bond is formed when the carbonyl carbon donates a lone pair of electrons to the vacant orbital of the metal.
$A$ $\pi$ bond is formed by the donation of a pair of electrons from the filled metal $d$ orbital into the vacant anti-bonding $\pi^{*}$ orbital of the $CO$ ligand (also known as back bonding).
The $\sigma$ bond strengthens the $\pi$ bond and vice-versa. Thus,a synergic effect is created due to this metal-ligand bonding,which strengthens the bond between $CO$ and the metal.