Nitrogen inversion
Nitrogen inversion
In chemistry, a nitrogen compound like ammonia in a trigonal pyramid geometry undergoes rapid nitrogen inversion whereby the molecule turns inside out.
This interconversion is a room temperature process because the energy barrier (18 KJ/mole) is relatively small. Contrast this to methane which does not show inversion.
Even if all three substituents on the nitrogen in an amine are different, rapid inversion would prevent the nitrogen atom from becoming a permanent chiral center, since such inversion becomes effectively like a conformational change. However, if the nitrogen is a bridgehead atom in a bicyclo or a similar compound where it cannot invert around the lone electron pair, then the nitrogen atom could be a chiral center if all three substituents on it are effectively different. An example of such a compound is Tröger’s base.