The ligand called $\pi$ acid is

The ligand called $\pi$ acid is
  1. $\mathrm{CO}$
  2. $\mathrm{NH}_3$
  3. $\mathrm{C}_2 \mathrm{O}_4^{2-}$
  4. ethylene diamine.

Solution

Carbon monoxide is $\pi$-acid ligand as it characterises both metal to carbon and carbon to metal bonding. The latter is known as $\pi$-acidic character.

Asked in: NEET 2008 (Mains)

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