Vibrational spectra and analysis of acetohydrazide CH 3–CO–NH–NH 2

Abstract

The structural stability of acetohydrazide CH 3–CO–NH–NH 2 was investigated by DFT-B3LYP and ab initio MP2 calculations with 6-311+G** basis set. The C–N rotational barrier in the molecule was calculated to be about 26 kcal/mol that suggested the planar sp 2 nature of the nitrogen atom of the central NH moiety. The N atom of the terminal NH 2 group was predicted to highly prefer the pyramidal sp 3 structure with an inversion barrier of about 7–8 kcal/mol. The molecule was predicted to have a trans-syn (N–H bond is trans with respect to C O bond and NH 2 moiety is syn to C–N bond) conformation as the lowest energy structure. The vibrational frequencies were computed at B3LYP level of theory and normal coordinate calculations were carried out for the trans-syn acetohydrazide. Complete vibrational assignments were made on the basis of normal coordinate analyses and experimental infrared and Raman data.