I've been learning about using MO theory to explain why $\ce{BH3}$ and $\ce{NH3}$ have different geometries and by following the line of reasoning used to rationalise the differences in geometry I came to wonder whether ionisation or the addition of electrons to a molecule can change its geometry.
Eg: $\ce{NH3}$ is trigonal pyramidal but an $\ce{NH3^2+}$ ion would have the same electron configuration as $\ce{BH3}$, which is trigonal planar; does this mean $\ce{NH3^2+}$ would be trigonal planar?
Edit: My bad when I first posted this I wrote $\ce{NH3^2-}$ but meant $\ce{NH3^2+}$, this was just an example, my main objective was to find out whether changing the geometry through ionisation was possible.