Question #988ef

May 1, 2017

If you count all your electrons, you will find that there are seven electron groups.

This seventh electron pair actually distorts the geometry so that its geometry LOOKS more like two ${\text{NH}}_{3}$ molecules (so-called "${C}_{3 v}$" symmetry) with their $\text{N}$ atoms aligned towards each other, rather than an octahedral shape (so-called "${O}_{h}$" symmetry).

Hence, it is more like this:

(notice the similarity to this.)

The distortion mostly happens on one plane bisecting the two previously-octahedral faces, apparently, in order for it to have the distorted symmetry previously mentioned (${C}_{3 v}$).