OXIDATION CHEMISTRY OF A URANIUM(III) ARYLOXIDE

The oxidation chemistry of the uranium(III) aryloxide complex U(OAr)(3 ) (OAr = 2,6-di-tert-butylphenoxide) has been explored with a variety of one-electron oxidants. Oxidation of U(OAr)(3) with either AgBF4 or AgPF6 produces the uranium(IV) fluoride FU(OAr)(3), 1. The analogous c hloride compound, CIU(OAr)(3), 2, is prepared by reaction with either benzyl chloride or PCl5. Oxidation by AgBr, CBr4, or PBr5 yields BrU(O Ar)(3), 3. Oxidation of U(OAr)(3) by elemental iodine yields IU(OAr)(3 ), 4. Compound 4 crystallizes in the space group P2(1)/n, with unit ce ll dimensions a = 20.005(6) Angstrom, b = 10.228(4) Angstrom, c = 21.8 79(6) Angstrom, beta = 115.30(2)degrees, V = 4047(2) Angstrom(3), and Z = 4. Oxidation of U(OAr)(3) with CL (carbon tetraiodide) does not yi eld 4 but rather gives rise to I2U(OAr)(2), 5. Orthorhombic crystals o f the THF adduct I2U(OAr)(2)(THF) were obtained from THF/hexane. I2U(O Ar)(2)(THF) crystallizes in the space grpup Pbca, with unit cell dimen sions a = 18.197(2) Angstrom, b = 17.866(2) Angstrom, c = 20.930(3) An gstrom, V = 6804.5(14) Angstrom(3), and Z = 8. The chalcogenide-bridge d compounds (ArO)(3)U-O-U(OAr)(3), 6, and (ArO)(3)U-S-U(OAr)(3), 7, ca n be prepared by reaction with a variety of chalcogen-donor reagents; reaction of the tris(aryloxido)uranium complex with N2O, NO, Me(3)NO, or pyNO yields compound 6, while reaction with either COS or Ph(3)P=S affords 7. Compound 7 crystallizes as a diethyl ether solvate in the s pace group P1 $($) over bar$$, 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 = 224 7.4(11) Angstrom(3), and Z = 1. Oxidation of U(OAr)(3) by molecular ox ygen does not result in the isolation of the oxo-bridged dinuclear spe cies but in the formation of the known uranium(IV) compound U(OAr)(4) by ligand redistribution.