Preferences of the oxalamide and hydrazide moieties in vacuum and aqueous solution.: A comparison with the amide functionality

A theoretical study of the conformational preferences, changes in energy, and charge distribution for the oxalamide and hydrazide moieties of N,N'-dimethyloxalamide and N,N'-diacetylhydrazine is presented. Both gas-phase and aqueous environments have been simulated at the ab initio level using different basis sets and including electron correlation effects at the MP4 level. Three and four minimum energy conformations have been found for the oxalamide and hydrazide moieties, respectively. Results are in agreement with available experimental data obtained by X-ray crystallography. The inclusion of water largely affects not only the relative energy between the minima but also the charge distribution of the different structures. The main trends predicted for the oxalamide and hydrazide groups have been compared with those displayed by the amide bond of N-methyacetamide, which were computed at the same levels of theory.