Spectroscopic (FTIR, FT-Raman), molecular electrostatic potential, NBO and HOMO–LUMO analysis of P-bromobenzene sulfonyl chloride based on DFT calculations

Abstract

The FTIR and FT-Raman spectra of P-bromobenzene sulfonyl chloride (P-BBSC) have been recorded in the regions 4000–400cm−1 and 3500–50cm−1, respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by density functional theory (DFT/B3LYP) method. A good agreement between experimental and calculated normal modes of vibrations has been observed. A detailed interpretation of the infrared and Raman spectra of P-BBSC is also reported based on total energy distribution (TED). Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The MEP map shows the negative potential sites are on oxygen atoms as well as the positive potential sites are around the hydrogen atoms. The UV–vis spectral analysis of P-BBSC has also been done which confirms the charge transfer of the molecule.