Nuclear magnetic resonance studies of preferential solvation. Part 3.—Thermodynamic treatment involving change of solvation number, and application to dimethyl sulphoxide-containing solvents

Abstract

Studies of ⁷Li and ¹³³Cs ion n.m.r. chemical shifts in dimethyl sulphoxide (DMSO)+ water mixtures, have been interpreted in terms of a series of competitive equilibria in which the solvation number of the ions for DMSO is half that for water. It is concluded that nitrate ions are preferentially solvated by DMSO and Li⁺ by water. The treatment has also been applied to ¹³³Cs shift data for sulpholan and water mixtures, and it is concluded that caesium ions are solvated by the organic component.