Vibrational spectroscopic (FTIR and FT Raman) studies, first order hyperpolarizabilities and HOMO, LUMO analysis of p-toluenesulfonyl isocyanate using ab initio HF and DFT methods

The Fourier transform infrared (FTIR) and FT Raman spectra of p-toluenesulfonyl isocyanate (p-tosyl isocyanate) have been measured. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges have been calculated by using ab initio HF and density functional theory calculation (B3LYP) with 6-311+G(d,p) basis set. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT Raman data. The thermodynamic functions of the title compound were also performed with the aid of HF/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory. Simulated FTIR and FT Raman spectra for p-tosyl isocyanate showed good agreement with the observed spectra. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The dipole moment (μ), polarizability (α) and the hyperpolarizability (β) values of the investigated molecule have been computed using HF and B3LYP methods.

Graphical abstract. An extensive study on the vibrational, structural, thermodynamic characteristics as well as the electronic properties of p-toluenesulfonyl isocyanate was carried out using ab initio and DFT methods. The experimental vibrational frequencies were assigned and interpreted satisfactorily. The electronic properties, such as HOMO and LUMO energies, were performed by ab initio HF and DFT approach.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The FT-IR and FT-Raman spectra of p-tolsyl isocyanate were studied. ► The calculations were carried out for p-tolsyl isocyanate at HF/B3LYP/6-311+G(d,p). ► p-Tolsyl isocyanate derivatives exhibit important biological properties. ► A comparison with the IR and Raman spectra of p-tolsyl isocyanate have been reported. ► Hyperpolarizabilities and HOMO and LUMO energies were performed by HF/DFT approach.