Question

The main factor responsible for weak acidic nature of B-F bonds in $B{F}_3$ molecule is:

• A. Large electronegativity of F
• B. Three centre and two electron bonds in $B{F}_3$
• C. $p\pi -d\pi$ back bonding
• D. $p\pi -p\pi$ back bonding

Answer 1

The correct option is D $p\pi -p\pi$ back bonding

It is $p\pi -p\pi$ back bonding involving B and F atom responsible for the acidic nature of boron halides as $B{F}_3<BC{l}_3<BB{r}_3<B{I}_3$, smaller atoms show more back bonding