Ion solvation and association in LiClO4/sulfolane solution:: a vibrational spectroscopic and molecular orbital study

Solvation interaction and ion association in solutions of lithium pelchlorate/sulfolane have been studied by using infrared and Raman spectra as a function of concentration of lithium perchlorate. The band changes of antisymmetric OSO stretch, antisymmetric CSC stretch, -SO2 wag and twist suggest that there is an interaction between Lit and sulfolane molecules, and the site of solvation is the oxygen atom of -SO2 group. The molecular orbital calculation supports this suggestion. On the other hand, the apparent solvation number was calculated, and the band fitting for the ClO4- band reveals the presence of contact ion pair, solvent separated ion pair acid free ClO4- anion in the concentrated solutions. (C) 2001 Elsevier Science B.V. All rights reserved.