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New thermochemical parameter for describing solvent effects on IR stretching vibration frequencies. Communication 1. Assessment of van der Waals interactions.

Solomonov BN, Varfolomeev MA, Novikov VB, Klimovitskii AE

Chemical Institute, Kazan State University, Kremlevskaya 18, Kazan 420008, Russia. Boris.Solomonov@ksu.ru

Solvent effects on OH stretching vibrations in several complexes with hydrogen bonding have been investigated by FTIR spectroscopy. To assess the influence of van der Waals (vdW) interactions on frequency shifts, a new parameter of solvent, square root deltacavhS, is proposed. This parameter has been derived from equations describing enthalpy of non-specific solvation. Linear correlation was established between the OH frequency shift (with respect to the gas phase) and parameter square root deltacavhS for a series of complexes of aliphatic alcohols with standard proton acceptors. Linear correlations with square root deltacavhS were also observed for a series of "free" O-H and also C=O, P=O, S=O and C-Br stretching vibrations. A new method is proposed for estimating the gas-phase stretching frequency from IR spectra of solutions. In addition, frequencies of "free" X-H groups in neat bases were deduced from the experimental data.

Published 10 May 2006 in Spectrochim Acta A Mol Biomol Spectrosc, 64(2): 397-404.
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