Question

Which of the following compounds has $2p\pi -2p\pi$ bond?

• A. $B{F}_3$
• B. $BC{l}_3$
• C. $BB{r}_3$
• D. $B{I}_3$

Answer 1

Answer: (A)

$B{F}_3$

$B{F}_3$ has $2p\pi -2p\pi$ bonding. Boron is electron deficient as it has only $6$ electrons in the outermost shell. $F$ has a tendency to back donate its lone pair of electrons to the empty p-orbital of $B$ due to identical size of 2p orbitals of $B$ and $F$. Rest of the halogens have a lesser tendency for $2p\pi -2p\pi$ bonding due to larger size difference.