Question

The bond dissociation energy of `B-F` in `BF_(3)` is `646 kJ mol^(-1)` whereas that of `C-F` in `CF_(4)` is `515 kJ mol^(-1)`. The correct reason for higher `B-F` bond dissociation energy as compared to that of `C-F` in `CF_(4)` is
A. Smaller size of `B`-atom as compared to that of `C` atom
B. Stronger the bond between `B` and `F` in `BF_(3)` as compared to `C-F` in `CF_(4)`
C. Significant `p pi-p pi` interaction between `B` and `F` in `BF_(3)` whereas there is no possibility of such interaction between `C` and `F` in `CF_(4)`
D. Lower degree of `p pi- p pi` interaction between `B` and `F` in `BF_(3)` than that between `C` and `F` in `CF_(4)`

Answer 1

Correct Answer - C
In `BF_(3)` there is considerable `p pi- p pi` interaction between unfilled `p`-orbital (having no electron) over boron and the lone pair of electrons over fluorine in `2p` orbital