Chlorination of Pu and U Metal Using GaCl₃

The oxidative chlorination of the plutonium metal was achieved through a reaction with gallium(III) chloride (GaCl₃). In DME (DME = 1,2-dimethoxyethane) as the solvent, substoichiometric (2.8 equiv) amounts of GaCl₃ were added, which consumed roughly 60% of the plutonium metal over the course of 10 days. The salt species [PuCl(dme)][GaCl] was isolated as pale-purple crystals, and both solid-state and solution UV-vis-NIR spectroscopies were consistent with the formation of a trivalent plutonium complex. The analogous reaction was performed with uranium metal, generating a dicationic trivalent uranium complex crystallized as the [UCl(dme)][GaCl] salt. The extraction of [UCl(dme)][GaCl] in DME at 70 °C followed by crystallization produced [{U(dme)}(μ-Cl)][GaCl], a product arising from the loss of GaCl₃. This method of halogenation worked on a small scale for plutonium and uranium, providing a route to cationic Pu³⁺ and dicationic U³⁺ complexes using GaCl₃ in DME.