Question

Which of the following ligands is called $\pi -$ acceptors?
CO $C{N}^{-}$ $N{O}^{+}$
$\left(I\right)$ $\left(II\right)$ $\left(III\right)$

• A. I, II, III correct
• B. I, II only correct
• C. II, III only correct
• D. III only correct

Answer 1

The correct option is A I, II, III correct

As $CO,C{N}^{-}andN{O}^{+}$ all contains double bond and after donating electron they become electron deficient so they get electron from metal through backbonding in their $\pi$ orbitals so they all are $\pi$ acceptors.