Vibrational spectroscopy investigation using ab initio and DFT vibrational analysis of 7-chloro-2-methylamino-5-phenyl-3H-1,4-benzodiazepine-4-oxide.

The FT-IR and FT-Raman spectrum of 7-chloro-2-methylamino-5-phenyl-3H-1, 4-benzodiazepine-4-oxide (7CMP4BO) has been recorded in the region 4000-400 and 4000-100 cm(-1) respectively. The optimized geometry, Thermodynamic properties, NBO, Molecular Electrostatic Potentials, PES, frequency and intensity of the vibrational bands of 7CMP4BO were obtained by the ab initio HF and density functional theory (DFT), B3LYP/6-31G (d,p) basis set. The molecule orbital contributions were studied by using the total (TDOS), partial (PDOS), and overlap population (OPDOS) density of states. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically calculated values.