Oxidation Chemistry of a Uranium(III) Aryloxide

The oxidation chemistry of the uranium(III) aryloxide complex U(OAr){sub 3} (OAr=2,6-di-tert-butylphenoxide) has been explored with a variety of one-electron oxidants. Oxidation of U(OAr){sub 3} with either AgBF{sub 4} or AgPF{sub 6} produces the uranium(IV) fluoride FU(OAr){sub 3}, 1. The analogous chloride compound, ClU(OAr){sub 3}, 2, is prepared by reaction with either benzyl chloride or PCl{sub 5}. Oxidation by AgBr, CBr{sub 4} or PBr{sub 5} yields BrU(OAr){sub 3}, 3. Oxidation of U(OAr){sub 3} by elemental iodine yields IU(OAr){sub 3}, 4. Compound 4 crystallizes in the space group P2{sub 1}/n, with unit cell dimensions a = 20.005(6) {angstrom}, b = 10.228(4) {angstrom}, {beta} = 115.30(2){degrees}, V = 4047(2) {angstrom}{sup 3}, and Z = 4. Oxidation of U(OAr){sub 3} with CI{sub 4} (carbon tetraiodide) does not yield 4 but rather gives rise to I{sub 2}U(OAr){sub 2}, 5. Orthorhombic crystals of the THF adduct I{sub 2}U(OAr){sub 2}(THF) were obtained from THF/hexane. I{sub 2}U(OAr){sub 2}(THF) crystallizes in the space group Pbca, with unit cell dimensions a = 18.197(2) {angstrom}, b = 17.866(2) {angstrom}, c = 20.930(3) {angstrom}, V = 6804.5(14) {angstrom}{sup 3}, and Z = 8. The chalcogenide-bridged compounds (ArO){sub 3}U-O-U(OAr){sub 3}, 6, and (ArO){sub 3}U-S-U-(OAr){sub 3}, 7, can be prepared by reaction with a variety of chalogen-donor reagents with either COS or Ph{sub 3}P=S affords 7. Compound 7 crystallizes as a diethyl ether solvate in the space group P{bar 1}, with unit cell dimensions a = 13.290(3) {angstrom}, b = 13.744(4) {angstrom}, c = 14.643(5) {angstrom}, {alpha} = 81.41(2){degrees}, {beta} = 65.36(2){degrees}, {gamma}=67.58(2){degrees}, V = 2247.4-(11) {angstrom}{sup 3}, and Z=1. Oxidation of U(OAr){sub 3} by molecular oxygen does not result in the isolation of the oxobridged dinuclear species but in the formation of the known uranium(IV) compound U(OAr){sub 4} by ligand redistribution.