Preparations, structures and thermal decomposition of some bis(pentafluorobenzoato)dioxouranium(VI) complexes

Glen B. Deacon, Peter I. Mackinnon, John C. Taylor

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Reaction Of UO2(O2CCH3)2 with pentafluorobenzoic acid yields UO2(O2CC6F5)2, which has been converted into the solvated complexes UO2(O2CC6F5)2L2·S [L2 = 2,2′-bipyridyl (bpy), S = 0.33 (PhH) or 0.07 (t-BuOH); L = Ph3PO, S = t-BuOH; L = Ph3AsO, S = 0.40 (t-BuOH)] and the solvent free UO2(O2CC6F5)2L2 [L2 = bpy; L = Ph3PO]. The crystal structure of UO2(O2CC6F5)2bpy (orthorhombic, space group P212121; a = 18.45(2), b = 18.94(2), c = 7.069(8) Å, Z = 4] reveals distorted hexagonal bipyramidal stereochemistry with a trans UO2 group, chelating pentafluorobenzoate ligands, and chelating 2,2′-bipyridyl, which is significantly displaced from the hexagonal plane. The structure of UO2(O2CC6F5)2(OPPh3)2·t-BuOH [rhombohedral, space group R3; a = 21.51(3) Å, α = 117.28(5)°, Z = 3] shows trans UO2, pseudo trans Ph3PO ligands, and one unidentate and one disordered chelating pentafluorobenzoate ligand, whilst t-BuOH could not be located because it is highly disordered. Relationships between ν (CO2) frequencies and the carboxylate coordination are discussed, and UO2(O2CC6F5)2(OAsPh3)2.0.40 (t-BuOH) is considered to have stereochemistry similar to that of the phosphine oxide complex. The complexes undergo decarboxylation in dimethyl sulphoxide yielding pentafluorobenzene and carbonatodioxouranium(VI) species not UO2(C6F5)2 derivatives. 

Original languageEnglish
Pages (from-to)103-113
Number of pages11
Issue number1
Publication statusPublished - 1985

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