FTIR and FT Raman spectra, vibrational assignments, ab initio, DFT and normal coordinate analysis of α,α dichlorotoluene

The vibrational spectra of α,α dichlorotoluene have been recorded using PerkinElmer 521 spectrometer in the range 3600–100 cm−1. A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions, relative intensities, fundamentals, overtones and combination bands. The fundamental vibrational frequencies, intensity of vibrational spectra and the optimized geometrical parameters of the title compound were evaluated using density functional theory (DFT) with the standard HF/6-31G(d) and were scaled using scale factor which yielded a good agreement between observed and calculated frequencies. With hope of providing more and effective information on the fundamental vibrations, a normal coordinate analysis has been performed by assuming Cs point group symmetry. The results of the calculations were applied to simulated infrared and Raman spectra of the title compound which showed excellent agreement with the observed spectra.