Ion-ion-solvent interactions in solution. II. Solutions of LiClO₄ in diethyl ether

Abstract

.Vibrational spectra and ³⁵Cl, ¹³C, ⁷Li and ¹H n.m.r. spectra of anhydrous solutions of LiClO₄ in diethyl ether have been studied. There is no evidence for the formation of free ions down to 0.1 M concentration of salt. Two salt species having concentration-dependent distributions are identified, these being contact ion pairs and ion aggregates. The salt species are solvated with one mole of solvent per mole of salt. The preferred conformation of the diethyl ether solvate molecule is trms-gauche. For pure dlethyl ether at 25°C the trans-trans → trans-gauche equilibrium has ΔH 5.85 kJ mol^-1 and ΔS 19.5 J K^-1 mol^-1. The ΔH value is not influenced by the presence of salt, but ΔS increases as the salt concentration increases until at 4 M LiClO₄ the value is 37.6 J K^-1 mol^-1.