Vibrational Spectra, Assignments and Ab initio/DFT Analysis for 2-Methyl-3-nitrophenyl isocyanate

The FT-IR (4000-400cm(-1)) and Raman (3200-100cm(-1)) spectral measurements have been made for 2-Methyl-3-nitrophenyl isocyanate. Electronic energy, optimized geometry and harmonic vibrational spectra have been computed using ab initio and DFT methods, namely, at RHF/6-311G* and B3LYP/6-311G* levels of theory. The methyl, nitro and isocyanate vibrations observed in their characteristic regions, have been accurately computed by the B3LYP/6-311G* level. Computed low frequencies have been assigned to out-of-plane, wagging and torsional vibrations of these groups. A complete assignment of the observed as well as computed spectra has been proposed.