JEE Main 2022 — Chemistry Inorganic Chemistry

Synergic bonding involves transference of electrons from ligands to metal. The transference of electrons takes place from filled metal orbitals to anti-bonding orbitals of ligands. It is a bond between a carbonyl group acting as a ligand and a metal. Synergic bonding means self strengthening bond. More the number of d electrons on the central metal ion more the synergic bonding. In metal carbonyls' oxidation state of the metal is zero.

In the complex $[\mathrm{Mn}{(\mathrm{CO})}_{5}]$[Mn(CO)5​], the electronic configuration of $\mathrm{Mn}$Mn is $3{d}^{5}4{s}^{2}$3d54s2. As carbon monoxide is a strong field, pairing of electrons occurs. Hence, the new electronic configuration of $\mathrm{Mn}$Mn is $3{d}^{7}$3d7.

In the case of $[{\mathrm{Mn}}_{2}{(\mathrm{CO})}_{10}]$[Mn2​(CO)10​] also electronic configuration after pairing of electrons is $3{d}^{7}$3d7.

In the complex $[\mathrm{Cr}{(\mathrm{CO})}_{6}]$[Cr(CO)6​] , the electronic configuration of $\mathrm{Cr}$Cr is $3{d}^{5}4{s}^{1}$3d54s1 . As carbon monoxide is a strong field, pairing of electrons occurs. Hence, the new electronic configuration of $\mathrm{Cr}$Cr is $3{d}^{6}$3d6

All of these compounds can show synergic bonding.