# What is the molecular geometry of the BCl_3 molecule?

Nov 21, 2016

$\text{Boron trichloride}$ is trigonal planar.
There are 3 boron-centred electrons, which form $3 \times B - C l$ bonds. The geometry around boron is thus trigonal planar with $\angle C l - B - C l = {120}^{\circ}$.
Now much of the chemistry of boron relates to the filling of its empty $\text{p-orbital}$; with extra halide ligand, $\text{tetrachloroborate anion}$ is formed:
$B C {l}_{3} + C {l}^{-} \rightarrow B C {l}_{4}^{-}$