In the hydrolysis of trans- $\left[\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}(\mathrm{A})\right]^{+}$if the leaving group is chloride, the formation of cis product is the least, when A is
(a)$\mathrm{NO}_{2}^{-}$
(b)$\mathrm{NCS}^{-}$
(c)$\mathrm{Cl}^{-}$
(d)$\mathrm{OH}^{-}$
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
The π-acceptor NO₂⁻ stabilises the square-pyramidal intermediate, so hydrolysis proceeds with retention (trans product); π-donors (Cl⁻, OH⁻, NCS⁻) favour the trigonal-bipyramidal intermediate and give more cis product.