(R)-(-)-2-Pyrrolidinemethanol: A combined experimental and DFT vibrational analysis of monomers, dimers and hydrogen...

Experimental IR and solution phase spectra of (R)-(-)-2-Pyrrolidinemethanol showing evidence of hydrogen bonding have been interpreted by computing vibrational modes of monomers and dimers with the molecular species due to intra- and inter-molecular hydrogen bonding, at B3LYP/6-311+G(d,p) level density functional theoretical calculations. Computed vibrational frequencies of Boltzmann population-weighted dimers for stretching and bending of O-H and N-H modes associated with the inter-molecular N-H⋯O and O-H⋯O hydrogen bonding are in good agreement with the measured IR absorption, Raman and solution-phase IR values near 3289 cm(-1), 3450 cm(-1) and 1400-1300 cm(-1). Further, the H⋯O length is shorter in O-H⋯O than in N-H⋯O by ∼10% suggesting that O-H⋯O is a stronger bond. While the solution-phase IR spectral features suggest strong inter-molecular associations, it is short of demonstrating which type of bonding is dominant factor. We conclude that the measured IR, Raman and solution-phase IR spectral features indicate the presence of both types of hydrogen bonds.