FT-IR and FT-Raman spectra, thermo dynamical behavior, HOMO and LUMO, UV, NLO properties, computed frequency estimation analysis and electronic structure calculations on α-bromotoluene

In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100–4000 cm−1 and 50–4000 cm−1, respectively, for the title molecules. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartee Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The influences of bromine atom and methyl group on the geometry of benzene and its normal modes of vibrations have also been discussed. The results of the calculations were applied to simulated spectra of the title compounds, which show excellent agreement with observed spectra.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Molecular structure of α-bromotoluene molecule was studied using HF and DFT/B3LYP. ► All results were compared with experimental FT-IR and FT-Raman spectra. ► HOMO and LUMO, absorption wavelength and excitation energies were performed. ► The important thermodynamical parameters are reported. ► Molecular electrostatic potential distribution of α-bromotoluene was calculated.