Are 1,2-dihydrodiazetes aromatic? An experimental and computational investigation

J Org Chem. 2002 Sep 20;67(19):6699-704. doi: 10.1021/jo026082m.

Abstract

A thorough experimental and computational investigation of the aromaticity of the 1,2-dihydrodiazete ring system was carried out. The X-ray crystal structure of 1,2-dihydrodiazete 6 is reported, and the alkene-like reactivity of compound 6 is described. The compound's structure and reactivity suggest that 6 is not aromatic. This conclusion is corroborated by computational results on 6 and related compounds including homodesmotic reactions to test for aromatic stabilization, NICS calculations, and NBO calculations. Compound 6, and 1,2-dihydrodiazetes in general, are concluded to be strained heterocycles with no indication for aromatic stabilization.