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

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: 105kex.′(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.