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)(3)tacn)U] and [(((ArO)-Ar-Ad)(3)N) 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)(3)tacn)U}(2)(mu-E)] and [{(((ArO)-Ar-Ad)(3)N)U}(2)(mu-E)] (E = S, Se). Under reducing conditions, [(((ArO)-Ar-Ad)(3)N)U] reacts with elemental sulfur, selenium and tellurium to yield the mid-valent dinuclear bis-mu-chalcogenide complexes [Na(DME)(3)](2)[{(((ArO)-Ar-Ad)(3)N) U}(2)(mu-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 [{(((ArO)-Ar-Ad)(3)N) U}(2)(mu-O)(2)] was also synthesized. A short uranium-uranium distance in this complex with a U(mu-O)(2)U diamond-core may account for the unusual temperature-dependent magnetic behavior.