Dielectric Spectroscopy of Cesium Fluoride in Methanol

Abstract

Dielec. relaxation spectra have been measured at frequencies up to 20 GHz for CsF solns. in methanol (MeOH); concns. up to about 1 mol-L, temp. 25 °C. Spectra were also obtained for a few concns. of the much less sol. KF. Spectra were also obtained for a few concns. of the much less sol. KF. The data show that CsF forms a solvent shared ion pair (SSIP) in MeOH solns. Detailed consideration of the possible geometries and comparison with earlier conductometric data suggest that the ion pair involves an oriented solvent mol. located at a vertex of one of the coordination sites of the cesium, rather than a conventional SSIP. Solvation nos. of the ions, estd. via the modified Cavell equation, are unrealistically large. This suggests, consistent with the large dielec. decrement and the cond. data, that the ions significantly break down the chain structure of MeOH.