Tautomers and conformers of malonamide, NH2-C(O)-CH2-C(O)-NH2: vibrational analysis, NMR spectra and ab initio calculations.

The conformational and tautomeric compositions of malonamide, NH2-C(O)-CH2-C(O)-NH2 were determined by vibrational spectroscopy and theoretical calculations (HF/6-31G*, B3PW91/6-31G*). Solid state Fourier transform infrared and Raman spectra were analysed. They reveal the existence of a diketo tautomer. Theoretical calculations predict a diketo structure belonging to the C1 symmetry group. No enol form is present in the molecule in the solid. 13C-NMR studies show only signals of a diketo tautomer.