Phase Equilibria and Ionic Solvation in the Lithium Tetrafluoroborate-Dimethylsulfoxide System

The phase diagram and electrical conductivity isotherms for the lithium tetrafluoroborate (LiBF4)-dimethylsulfoxide (DMSO) system and Raman spectra of DMSO and the LiBF4-DMSO solution were studied. Spectroscopic signatures of a H-bond between DMSO and BF4 (-) ions were found. The bonds of Li+ ions to the solvent were stronger than the bonds in DMSO dimers because formation of the solvate destroyed dimeric DMSO molecules. The tau(omega) values for DMSO molecules in the Li+-ion solvate shell of the LiBF4-DMSO system were similar to those for associated solvent molecules.