Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV and NBO analysis of 2-chlorobenzonitrile by density functional method.

In this work, we will report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV spectral analysis of 2-chlorobenzonitrile (2-ClBN). The FT-IR solid phase (4000-400 cm(-1)), and FT-Raman spectra (3500-50 cm(-1)) of 2-ClBN was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 2-ClBN in the ground state have been calculated by using the density functional methods (BLYP, B3LYP) with 6-31G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* anti bonding orbitals and E2 energies confirms the occurrence of ICT (Intra molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethanol solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. Finally calculated results were applied to simulated Infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Vibrational, NMR spectral studies of 2-furoic hydrazide by DFT and ab initio HF methods.

The Fourier transform infrared spectra, 1H NMR and 13C NMR spectra of 2-furoic hydrazide have been recorded. Optimized geometry, frequency and intensity of the vibrational bands of 2-furoic hydrazide were obtained by the density functional theory (DFT) and ab initio levels of theory and also 1H NMR, 13C NMR chemical shifts were calculated using 6-31G+(d,p) basis sets. The theoretical values were compared with experimental values.

Vibrational spectroscopic study and NBO analysis on bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane using DFT method.

In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO analysis of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane (BAMTM). The FT-Raman and FT-IR spectra of BAMTM were recorded in the solid phase. The molecular geometry, harmonic vibrational frequencies and bonding features of BAMTM in the ground state have been calculated by using density functional method (B3LYP) with standard 6-31G(d, p) basis set. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed which show good agreement with recorded spectra.