Orbital interaction in amino-ketones

Abstract

A study of the orbitals of α-aminoacetone and α-aminoacetaldehyde as a function of the two important torsions in these molecules is reported. The individual level shifts are much greater than the variation of the total energy. We identify four significant interactions affecting the level ordering. Each interaction has its distinctive conformational dependence. In order of decreasing spectroscopic importance the interactions are as follows. (1) Through bond coupling of the nitrogen and oxygen lone-pairs. (2) Through space interaction of these lone-pairs. (3) Hyperconjugation between the C–N σ* level and the carbonyl π-system. (4) Direct overlap of the nitrogen lone-pair with the carbonyl π-system.