Quantum chemical calculations, vibrational studies, HOMO–LUMO and NBO/NLMO analysis of 2-bromo-5-nitrothiazole

The complete vibrational assignment and analysis of the fundamental modes of 2-bromo-5-nitrothiazole (BNT) was carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The observed vibrational data were compared with the wavenumbers derived theoretically for the optimized geometry of the compound from the ab initio HF and DFT–B3LYP gradient calculations employing 6-311++G(d,p) basis set. Thermodynamic properties like entropy, heat capacity and zero point energy have been calculated for the molecule. HOMO–LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. Important non-linear properties such as electric dipole moment and first hyperpolarizability of BNT have been computed using B3LYP quantum chemical calculation.

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► The FT-IR and FT-Raman spectra of the title compound have been recorded.
► Optimized geometry, vibrational frequencies are obtained.
► The first hyperpolarizability has been determined.
► The HOMO and LUMO energies have been calculated.
► Stability of the molecule has been analyzed using NBO and NLMO analysis.