Question

Which of the following is electron deficient molecule?

• A. $B_2{H}_6$
• B. $C_2{H}_6$
• C. $P{H}_3$
• D. $Si{H}_4$

Answer 1

Answer: (A)

In $B_2{H}_6$, each $B$ - atom uses $s{p}^3$ - hybrid orbitals for bonding out of $4s{p}^3$ - hybrid orbitals, one orbital is empty. Here, one half filled orbital of other $B$ - atoms overlaps with one empty orbital of other $B$ - atom and half - filled orbitals of hydrogen atom resulting in $3$ centered two $e-$ bridge bonds. Thus, these bonds are electron deficient.