Ion association and solvation behavior of some lithium salts in tetrahydrofuran. A conductivity and Raman spectroscopic study

Accurate measurements of electrical conductivities and laser Raman spectra of solutions of lithium chloride (LiCl), lithium bromide (LiBr), lithium tetrafluoroborate (LiBF4) and lithium perchlorate (LiClO4) in tetrahydrofuran are reported. The conductivity data have been analyzed by the Fuoss-Krauss theory, yielding values for the ion-pair and triple-ion formation constants. The Raman spectra suggest the presence of a new signal of perchlorate ClO4- ions in solution, whereas there is no such evidence for the other investigated anions. The observed processes have been interpreted by an Eigen multistep mechanism. For each salt, the predominant portion is found to remain in the form of ion pairs, leaving only a small fraction of triple ions.