Chloride-exchange processes on gallium(III) in concentrated aqueous chloride solutions: a chlorine-35 and gallium-71 magnetic resonance study

Abstract

The equilibria between gallium(III) species have been investigated by ⁷¹Ga n.m.r. and the rates of chloride exchange determined by ³⁵Cl n.m.r. in two series of solutions in which the total chloride concentrations were 11.0 and 7.0M, and in which the ratio [HCl] : [LiCl] was varied over a wide range. The chloride-exchange dynamics are rationalised in terms of an associative exchange of chloride on [GaCl₄]^–. In 11M-hydrochloric acid: 10⁵k_ex.′(298 K)= 164 ± 8 l mol^–1 s^–1; ΔH^‡= 30.1 ± 1.5 kJ mol^–1; and ΔS^‡=–44 ± 5 J K^–1 mol^–1.