Select the correct statement(s) regarding `BF_(2)NH_(2)` molecule:

Options

A. FBF bond angle `lt120^(@)`
B. HNH bond angle `gt109^(@)28'`
C. HNH bond angle `lt109^(@)28'`
D. FBF bond angle `gt120^(@)`

Answer

A, B

Explanation

`2p_(pi)-2p_(pi)` back bonding
According to Bent's rule there is more p-character in `B-F` bond than in `B-N` bond, Hence FBF is less than `120^(@)`.
As size of `-NH_(2)` group is larger than F-atom hence repulsion between `-NH_(2)` group and F-atom is higher than between two F-atoms.
As lone pair of N-atom in `NH_(2)` group participate in back bonding hence `H-N-H` is greater than `109^(@)28'`. as hybridization of N is changing from `sp^(3)` towards close to `sp^(2)`