Chemistry - Coordination Chemistry Question with Solution | TestHub

Metal carbon bond in metal carbonyls possess both$\mathrm{\sigma }$and$\mathrm{\pi }$character.$\text{M}-\text{C}$$\mathrm{\pi }$bond is formed by donation of a pair of electrons from filled orbital of metal into vacant antibonding$\mathrm{\pi }$orbital of$\text{CO}$.$\text{CO}$bond length increases if M has more tendency to donate lone pair.

Tendency to donate lone pair is${\text{Fe}}^{2-}>{\text{Co}}^{-}>\text{Ni}>{\text{Mn}}^{+}$