The structure of N-aminoazoles: an experimental (X-ray and 15N NMR) and theoretical study

Abstract

INDO calculations with complete optimization of the geometries (INDO ∥ INDO) have been carried out on the seventeen parent N-methyl and N-aminoazoles. The results are consistent with the available experimental evidence and provide a coherent picture of the conformation of the sp³ amino group. The nitrogen-15 chemical shifts of eleven N-aminoazoles have been determined for the first time. Experimental determination of the geometry by X-ray crystallography has been carried out on 1 -aminobenzimidazole: P2₁/n,a= 7.972 5(4), b= 11.041 1 (4), c= 7.525 1 (3)Å, β= 94.435(3)°, and on 2-aminobenzotriazole: P2₁/c, a= 11.590 0 (5), b= 4.603 1 (8), c= 12.559 1 (8)Å, β= 109.914(4)°.