# Justifying the tremendous -I effect of -[NMe₃]⁺ by molecular orbital theory

The $\ce{-[NMe3]+}$ group is ranked almost at the first position in the -I effect series, which is often given at the very beginning of the teaching of general organic chemistry.

I know this can be justified by hyperconjugation, but I am interested in a rigorous justification by molecular orbital theory.

• This group has a positive charge, any molecular orbital effect will be negligible compared to that. – Martin - マーチン Aug 1 '18 at 16:02

$\ce{Me}$ is a pushing group which pushes electron towards the nitrogen atom. As a result electron concentration is towards the nitrogen atom.