Journal of Physical Chemistry A, Vol.103, No.24, 4673-4679, 1999
A study of the interaction between halomethanes and water-ice
The infrared spectra of a series of twenty-three halogenocarbon compounds co-deposited onto water-ice held at 12 K have been investigated. Perturbations to the water (D2O) sites which are not saturated in the absence of guests show distinct trends depending on the type and extent of halogen substitution in the occluded molecules. The data are quantified in terms of the IR spectral positions of the so-called "dangling bond" of water; interaction also leads to changes in the halogenocarbon compound IR spectra. It is clear from the results that the halomethanes interact through lone pair donation from a halogen atom to a deuterium atom of the water molecule. A high level of correlation is found between the shift in the dangling bond and both the charge density and the molecular polarizability within each separate series for compounds of the formula CFnH4-n, CClnH4-n, and CBrnH4-n (where n = 1-4). It is demonstrated that profiles correlating either ionization potentials or molecular polarizabilities for Cl- and Br-containing halogenocarbons with dangling bond shift provide an accurate method for predicting the respective physicochemical parameters. When a combined polarizability/charge interaction parameter is plotted against the dangling bond shift a straight line, also with predictive capabilities, results.