Question

Among $BM{e}_3$ , $B{F}_3$ , $BC{l}_3$ and $B_2{H}_6$ which one will be the best Lewis acid ?

• A. $BC{l}_3$
• B. $BM{e}_3$
• C. $B_2{H}_6$
• D. $B{F}_3$

Answer 1

Answer: (A)

Electron acceptors are acids among given choices.

(i) $B{F}_3$ and $BC{l}_3$ are better Lewis acid than $BM{e}_3$ and $B_2{H}_6$ due to -I eftect of $Cl$ and $F$.

(ii) Between $BC{l}_3$ and $B{F}_3,BC{l}_3$ is better Lewis acid due to lesser extent of $p\pi -p\pi$ back bonding in it.