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, a nd charge distribution for the oxalamide and hydrazide moieties of N,N'-dim ethyloxalamide and N,N'-diacetylhydrazine is presented. Both gas-phase and aqueous environments have been simulated at the ab initio level using diffe rent basis sets and including electron correlation effects at the MP4 level . Three and four minimum energy conformations have been found for the oxala mide and hydrazide moieties, respectively. Results are in agreement with av ailable experimental data obtained by X-ray crystallography. The inclusion of water largely affects not only the relative energy between the minima bu t also the charge distribution of the different structures. The main trends predicted for the oxalamide and hydrazide groups have been compared with t hose displayed by the amide bond of N-methyacetamide, which were computed a t the same levels of theory.