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)

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.