Which of the following has the longest C − O bond length? (Free C − O bond length in CO is 1 . 128 A o ).

Question

Aicharya · Accepted Answer

Metal carbon bond in metal carbonyls possess both

σ

and

π

character.

M - C

π

bond is formed by donation of a pair of electrons from filled orbital of metal into vacant antibonding

π

orbital of

CO

.

CO

bond length increases if M has more tendency to donate lone pair.
Tendency to donate lone pair is

{Fe}^{2 -} > {Co}^{-} > Ni > {Mn}^{+}

Solution