Werner-Type Complexes of Uranium(III) and (IV).

Transmetalation of the β-diketiminate salt [M][MenacnacPh] (M+ = Na or K; MenacnacPh- = {PhNC(CH3)}2CH-) with UI3(THF)4 resulted in the formation of the homoleptic, octahedral complex [U(MenacnacPh)3] (1). Green colored 1 was fully characterized by a solid-state X-ray diffraction analysis and a combination of UV/vis/NIR, NMR, and EPR spectroscopic studies as well as solid-state SQUID magnetization studies and density functional theory calculations. Electrochemical studies of 1 revealed this species to possess two anodic waves for the U(III/IV) and U(IV/V) redox couples, with the former being chemically accessible. Using mild oxidants, such as [CoCp2][PF6] or [FeCp2][Al{OC(CF3)3}4], yields the discrete salts [1][A] (A = PF6-, Al{OC(CF3)3}4-), whereas the anion exchange of [1][PF6] with NaBPh4 yields [1][BPh4].