In which of the following compounds B-F length is shortest?

Question

In which of the following compounds B-F length is shortest? (A) BF 4- (B) BF 3 arrow NH 3 (C) BF 3 (D) BF 3 arrow N ( CH 3)3

Tardigrade Admin · Accepted Answer

Only in BF 3 p π -p π back bonding is possible due to which B-F bond length is shortest. In other compounds, p- orbital at boron is not. vacant hence, p π -p π back bonding is not possible.

Q. In which of the following compounds $B - F$ length is shortest?

$B F_{4}^{-}$

$B F_{3} \to N H_{3}$

$B F_{3}$

$B F_{3} \to N (C H_{3})_{3}$

Only in $B F_{3} p π$ -p $π$ back bonding is possible due to which $B - F$ bond length is shortest. In other compounds, $p -$ orbital at boron is not. vacant hence, $p π - p π$ back bonding is not possible.

Q. In which of the following compounds B−F length is shortest?

BF4−​

BF3​→NH3​

BF3​

BF3​→N(CH3​)3​