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. Experime ntal spectra obtained at different concentrations have been compared with t he ab initio predictions of absorption and VCD spectra obtained with densit y functional theory using B3LYP/6-31G* basis set for nine different conform ers of (R)-2-butanol. The Boltzmann populations, obtained from Gibbs free e nergies, indicate the presence of all nine conformations for isolated molec ule. Vibrational assignments have been proposed with the observed bands ass igned mainly for the most stable conformers. The population weighted theore tical spectra are in satisfactory agreement with the experimental spectra o btained at dilute concentrations. The influence of intermolecular hydrogen bonding on the bands originating from C-O-H bending and C-O stretching is o bserved in the experimental spectra.