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 2 (dme) 3 ]­[GaCl 4 ] 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) 3 ]­[GaCl 4 ] 2 salt. The extraction of [UCl­(dme) 3 ]­[GaCl 4 ] 2 in DME at 70 °C followed by crystallization produced [{U­(dme) 3 } 2 (μ-Cl 3 )]­[GaCl 4 ] 3 , 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.