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

Abstract

Transmetalation of the β-diketiminate salt [M][^Menacnac^Ph] (M⁺ = Na or K; ^Menacnac^Ph- = {PhNC(CH₃)}₂CH^-) with UI₃(THF)₄ resulted in the formation of the homoleptic, octahedral complex [U(^Menacnac^Ph)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].