Which of the following statement is CORRECT for bonding in metal carbonyls?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Metal–carbon bond in metal carbonyls possesses both σ and π character.
In a metal carbonyl, CO is bonded to the metal through its carbon atom; the bond has a σ part (carbon lone pair to the metal) and a π part (back bonding from filled metal d orbitals into the π* orbital of CO).
So the metal–carbon bond possesses both σ and π character.
Why the other options are incorrect
Option (1) Metal–oxygen bond in metal carbonyls possesses both σ and π character — Incorrect. CO binds through carbon, so there is no metal–oxygen bond in a metal carbonyl.
Option (2) Metal–carbon bond in metal carbonyls possesses only σ character — Incorrect. This ignores the π back bonding from the metal d orbitals into the π* orbital of CO.
Option (3) Metal–carbon bond in metal carbonyls possesses only π character — Incorrect. This ignores the σ donation of the carbon lone pair, which forms the bond in the first place.
NCERT (2026-27 edition):
Bonding in Metal Carbonyls – …
