Molecular structure and vibrational spectra of Benzophenone hydrazone molecule by density functional theory

Quantum chemistry calculations have been performed to compute optimized geometry, NBO analysis, harmonic vibrational frequency along with intensities in IR spectrum by using B3LYP/6-31G∗ and B3LYP/6-311+G∗∗ levels for Benzophenone hydrazone (C13H12N2) in the ground state. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using MOLVIB program. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. A detailed interpretation of the infrared spectra of the title compound is reported. The shortening of CH bond length and blue shifting of the CH stretching wavenumber suggest the existence of improper weak CH…N hydrogen bonding, which is also confirmed by the natural bond orbital analysis. The theoretical spectrograms for FT-IR spectra of the title compound have also been constructed.