FT-IR, Raman and DFT study of 5-chloro-4-nitro-o-toluidine and NBO analysis with other halogen (Br, F) substitution

In this article the FT-IR and FT-Raman spectra of 5-chloro-4-nitro-o-toludine (CNOT) have been recorded and analyzed. The optimized geometry of the other halogen substitution (Br, F) has been computed with the help of density functional theory (DFT). The detailed interpretations of vibrational spectra of 5-chloro-4-nitro-o-toludine are furnished her, in terms of potential energy distribution analysis. Natural bond orbital analysis, HOMO–LUMO and molecular electrostatic potential surface on 5-chloro-4-nitro-o-toludine, 5-bromo-4-nitro-o-toludine and 5-fluoro-4-nitro-o-toludine were carried out for various intramolecular interactions that are responsible for the stabilization of the molecule. The thermodynamic functions were analyzed. The Mulliken charges, the values of electric dipole moment of the molecule were computed using DFT calculations obtained from Gaussian 09 software. We conclude that the observed and the calculated frequencies are found to be in good agreement.

► 5-Chloro-4-nitro-o-toludine is studied by HF and B3LYP.
► All results are compared with experimental FT-IR and FT-Raman spectra.
► The thermodynamic parameters were obtained for the range of temperature 100–700 K.
► The chemical parameters were calculated from the HOMO and LUMO values.
► NBO analysis on CNOT, BNOT and FNOT has been carried out.