α-Bromo-2,6-dichlorotoluene: Molecular structure, vibrational spectroscopy, natural bond orbital analysis and NMR studies

The FT-IR and FT-Raman spectra of α-bromo-2,6-dichlorotoluene (αBDCT) have been recorded. The structural and spectroscopic data of the molecule in the ground state have been calculated using Hartree Fock (HF) and Density Functional Theory (DFT)/B3LYP with the standard 6-31++G(d,p) basis set. The optimized molecular geometry, vibrational frequencies and atomic charges in the ground state are calculated. With the help of specific scaling procedures, the observed vibrational wavenumbers in FT-IR and FT-Raman spectra have been analyzed and assigned to different normal modes of the molecule. A detailed interpretation of the infrared and Raman spectra of αBDCT is also reported based on total energy distribution (TED). The 1H and 13C NMR chemical shifts have been calculated by gauge-including atomic orbital method with B3LYP/6-31++G(d,p) approach. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The theoretical results agree well with the observed spectra.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Toluene occurs naturally in crude oil and extracted during the refining process. ► Toluene is used in many industrial processes and commercial products. ► The FT-IR and FT-Raman spectra of αBDCT were studied. ► The calculations were carried out for αBDCT at HF and B3LYP methods. ► A comparison with the IR and Raman spectra of αBDCT have been constructed.