Structural studies on bio-active compounds. Part 2. The solid-state and solution conformations of N-methyl-2-nitroethenamine and related compounds

Abstract

The 1H n.m.r. spectra of NN-dimethyl-2-nitroethenamine, N-methyl-2-nitroethenamine, and 2-nitroethenamine in several solvents have been analysed. In the case of the monomethyl compound, the proportions of different rotamers about the CC and C–N bonds are found to be solvent dependent. An X-ray crystallographic study of this compound indicates inter-rather than intra-molecular hydrogen bonding in the solid; molecular orbital calculations predict three of the possible four conformers about these bonds to be of similar and much lower energy than the fourth.