Conformational and isomerizational studies of 3-N,N-dimethylhydrazino-2-acetyl propenenitrile using X-ray analysis, NMR and vibrational spectra, and ab initio calculations

The IR, Raman and NMR spectra of 3-N,N-dimethylhydrazino-2-acetyl propenenitrile (DMHAP) [(H3C)2NNHCHC(CN)(COCH3)] were measured. X-ray analysis revealed that DMHAP exists in solid state as ZZa conformer. Vibrational and NMR spectra confirmed the existence of only one ZZa conformer with an intramolecular hydrogen bond in less polar solvents and next two EZa and EZs conformers of E-isomer with Z-orientation of acetyl group and anti and syn orientation of dimethylhydrazino group in more polar environments. The observed IR and Raman bands were compared with harmonic vibrational frequencies, calculated using ab initio MP2 and DFT/B3LYP methods in 6-31G∗∗ basis set, and assigned on the basis of potential energy distribution. ition, the geometries and relative energies of the possible isomers and conformers of DMHAP were also evaluated on the same levels and compared with the X-ray data. The influence of environment polarity on this conformational equilibrium is discussed with respect to the SCRF solvent effect calculations using IEFPCM model.