SYNTHESIS AND REACTIONS OF U(III) COMPLEXES WITH TRIPODAL NITROGEN AND OXYGEN DONOR LIGANDS

Reaction of UI3(THF)(4) (where THF is tetrahydrofuran) with sodium or potassium hydrotris(3,5-dimethylpyrazolyl)borate ligand ((HBpz(3))(2) I (2) in 1:1 and 1:2 ratios gives the corresponding U(HBpz(3))I-2(THF )(2) (1) and U(HBpz(3))(2)I (2) complexes in excellent yields. Iodide abstraction from 2 with TIBPh(4) results in the formation of the cati onic complex [U(HBpz(3))(2)(THF)]BPh(4) (3). The solid state structur es of 1, 2 and 3 have been determined. Similar reactions with the anio nic tripodal oxygen donor ligand [(eta(5)-C5H5)Co{P(O)(OC2H5)(2)}(3)]( -) (L(OEt)) proceeded via oxidation of U3+ to U4+ and fragmentation of the ligand. The structures of some key compounds were established by X-ray crystallography. U(HBpz(3))I-2(THF)(2) readily reacts with two equivalents of KH(2)Bpz (pz=pyrazolyl) to give U(HBpz(3))(H(2)Bpz(2)) (2), but attempted substitution with other ligands led to mixtures or, in one case, displacement of the (HBpz(3))(-) ligand.