Vibrational circular dichroism:: Predominant conformations and intermolecular interactions in (R)-(-)-2-butanol

Vibrational absorption and circular dichroism spectra of (R)-(-)-2-butanol have been measured in CS2 solutions in the 2000-900 cm(-1) region. Experimental spectra obtained at different concentrations have been compared with the ab initio predictions of absorption and VCD spectra obtained with density functional theory using B3LYP/6-31G* basis set for nine different conformers of (R)-2-butanol. The Boltzmann populations, obtained from Gibbs free energies, indicate the presence of all nine conformations for isolated molecule. Vibrational assignments have been proposed with the observed bands assigned mainly for the most stable conformers. The population weighted theoretical spectra are in satisfactory agreement with the experimental spectra obtained at dilute concentrations. The influence of intermolecular hydrogen bonding on the bands originating from C-O-H bending and C-O stretching is observed in the experimental spectra.