Synthesis, FTIR, FT-Raman, UV–visible, ab initio and DFT studies on benzohydrazide

A systematic vibrational spectroscopic assignment and analysis of benzohydrazide (BH) has been carried out by using FTIR and FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations – ab initio (RHF) and hybrid density functional methods (B3LYP and B3PW91) performed with 6-31G(d,p) and 6-311++G(d,p) basis sets. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios and Raman activities have been computed. Potential energy distribution (PED) and normal mode analysis have also been performed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed and complete assignment of the observed spectra have been proposed. UV–visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by time-dependent DFT (TD-DFT) method. The geometrical, thermodynamical parameters and absorption wavelengths were compared with the experimental data. The interactions of carbonyl and hydrazide groups on the benzene ring skeletal modes were investigated.

Graphical abstractThe compound benzohydrazide (BH) was synthesized and systematic vibrational spectroscopic assignment and analysis of benzohydrazide (BH) has been carried out by using FTIR and FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations – ab initio (RHF) and hybrid density functional methods (B3LYP and B3PW91) performed with 6-31G(d,p) and 6-311++G(d,p) basis sets. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios and Raman activities have been computed for the most stable keto-I tautomer.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The compound benzohydrazide was synthesized. ► The vibrational assignment and analysis were carried out with FTIR and FT-Raman data. ► Molecular structural parameters of the geometry have been computed by HF and DFT methods. ► The electronic properties, were determined by time-dependent DFT (TD-DFT) method. ► The conformational analysis reveals three possible conformers for benzohydrazide. ► The keto-I form which has the CO and N–H bonds with Z configuration is the most stable.