Activation of elemental S, Se and Te with uranium(iii): bridging U–E–U (E = S, Se) and diamond-core complexes U–(E)2–U (E = O, S, Se, Te)

Abstract

Trivalent uranium complexes supported by tris(aryloxide) chelating ligands, [((^t-BuArO)₃tacn)U] and [((^AdArO)₃N)U], undergo activation of sulfur and selenium in their elemental forms, generating the mid-valent U(IV)/(U(IV) complexes of the type [{((^t-BuArO)₃tacn)U}₂(μ-E)] and [{((^AdArO)₃N)U}₂(μ-E)] (E = S, Se). Under reducing conditions, [((^AdArO)₃N)U] reacts with elemental sulfur, selenium and tellurium to yield the mid-valent dinuclear bis-μ-chalcogenide complexes [Na(DME)₃]₂[{((^AdArO)₃N)U}₂(μ-E)₂] (E = S, Se, Te) with the diamond-core structural motif and rare inorganic chalcogenide bridging ligands. For comparison, a unique high-valent U(V)/U(V) dinuclear complex [{((^AdArO)₃N)U}₂(μ-O)₂] was also synthesized. A short uranium–uranium distance in this complex with a U(μ-O)₂U diamond-core may account for the unusual temperature-dependent magnetic behavior.