Rotational isomers, density functional theory, vibrational spectroscopic studies, thermodynamic functions, NBO and HOMO-LUMO analyses of 2,6-Bis(chloromethyl)pyridine

The FT-IR and FT-Raman spectra of 2,6-Bis(chloromethyl)pyridine (BCMP) have been recorded in the regions 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The total energy calculations of BCMP were tried for the possible rotational isomers. The molecular structure, geometry optimization, vibrational frequencies were obtained by the HF and density functional theory (DFT/B3LYP) method with 6-311+G(d,p) basis set for the most stable rotational isomer "R3". The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The calculated HOMO and LUMO energies show that charge transfer occurs in the molecule. The stability of the molecule was analyzed using NBO analysis. The thermodynamic functions (heat capacity, entropy, vibrational partition function and Gibbs energy) were obtained for the range of temperature 100 K-700 K. (C) 2012 Elsevier B.V. All rights reserved.