Raman spectral studies of solutions of alkali metal perchlorates in dimethyl sulfoxide and water

Abstract

Raman spectra of solutions of alkali metal perchlorates in dimethyl sulfoxide (DMSO) in the Cl-O, C-S, and S=O stretching regions, as well as of perchlorates in aqueous solutions in the Cl-O stretching region are reported. The results are discussed in terms of half-bandwidths, relative intensities, and depolarization ratios. For H₂O the half-bandwidth of the Cl-O stretching band at ~935 cm^-1 is almost double the value in DMSO solutions. Solutions of perchlorates in DMSO show two symmetric bands in the Cl-O stretching region, whereas in aqueous solutions only one band is observed. The half-bandwidths in perchlorate solutions in DMSO for the C-S stretching band increase with increase in concentration of perchlorate compared to that of liquid DMSO. The band contours in the S=O stretching region in DMSO solutions also show significant changes. These observations are explained on the basis of formation of ion pairs of metal perchlorates in solutions of DMSO and ion hydrates in the case of aqueous solutions.