Density functional theory study on characterization of 3-chloro-1,2-benzisothiazole

The FT-IR and FT-Raman spectra of 3-chloro-1,2-benzisothiazole (CBT) have been recorded and analyzed. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of density functional theory (DFT) gradient calculations, using 6-311++G(d,p) basis set. Mulliken population analysis shows charge distribution on the molecule. Thermodynamic properties like entropy, heat capacity, zero point energy have been calculated for the molecule. The calculated HOMO and LUMO energies show the charge transfer occurs within the molecule. Stability of the molecule has been analyzed using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. The results of the calculations were applied to simulated spectra of the title compound, which show the excellent agreement with the observed spectra.

Graphical abstractThe FT-IR and FT-Raman spectra of 3-chloro-1,2-benzisothiazole (CBT) have been recorded and analyzed. The optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of DFT gradient calculations, using 6-311++G(d,p) basis set. Mulliken population analysis, calculation of thermodynamic properties, HOMO and LUMO energies have been carried out. Stability of the molecule has been analyzed using natural bond orbital analysis (NBO) and natural localized molecular orbital (NLMO) analysis.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The FT-IR and FT-Raman spectra of 3-chloro-1,2-benzisothiazole have been recorded. ► Optimized geometry, vibrational frequencies, IR and Raman intensities are obtained. ► The HOMO and LUMO energies have been calculated. ► Mulliken population analysis shows charge distribution on the molecule. ► Stability of the molecule has been analyzed using NBO and NLMO analysis.