Chlorination of Pu and U Metal Using GaCl₃

The oxidative chlorination of the plutonium metal wasachievedthrough 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 consumedroughly 60% of the plutonium metal over the course of 10 days. Thesalt species [PuCl ( 2 ) (dme) ( 3 ) ]-[GaCl ( 4 ) ] was isolated as pale-purple crystals, and both solid-stateand solution UV-vis-NIR spectroscopies were consistentwith the formation of a trivalent plutonium complex. The analogousreaction was performed with uranium metal, generating a dicationictrivalent uranium complex crystallized as the [UCl-(dme) ( 3 ) ]-[GaCl ( 4 ) ] ( 2 ) salt. The extraction of [UCl-(dme) ( 3 ) ]-[GaCl ( 4 ) ] ( 2 ) in DMEat 70 degrees C followed by crystallization produced [{U-(dme) ( 3 ) } ( 2 ) (mu-Cl ( 3 ) )]-[GaCl ( 4 ) ] ( 3 ), a productarising from the loss of GaCl3. This method of halogenationworked on a small scale for plutonium and uranium, providing a routeto cationic Pu3+ and dicationic U3+ complexesusing GaCl3 in DME. Gallium trichloride(GaCl3) can serve as a mildoxidant and chloride source for the generation of a plutonium-(III)complex, [PuCl ( 2 ) (dme) ( 3 ) ]-[GaCl ( 4 ) ] (dme = 1,2-dimethoxyethane), directly from plutoniummetal or for the generation of a dicationic uranium-(III) complex, [UCl-(dme) ( 3 ) ]-[GaCl ( 4 ) ] ( 2 ).