Chemistry - CHEMICAL BONDING Question with Solution | TestHub

The symmetrical cleavage of diborane ($B_2{H}_6$) occurs with ligands that are strong Lewis bases, forming $B{H}_3\cdot L$ adducts. $N{H}_3$ is a strong Lewis base, but it causes unsymmetrical cleavage of $B_2{H}_6$ due to the formation of an ionic adduct, $[B{H}_2(N{H}_3{)}_2{]}^{+}[B{H}_4{]}^{-}$.

Therefore, $N{H}_3$ is not responsible for symmetrical bond cleavage.