Reactivity of uranium(IV) bridged chalcogenido complexes UIV-E-UIV (E = S. Se) with elemental sulfur and selenium: synthesis of polychalcogenido-bridged uranium complexes

We report the syntheses, electronic properties, and molecular structures of a series of polychalcogenido-bridged dinuclear uranium species. These complexes are supported by the sterically encumbering but highly flexible, single N-anchored tris(aryloxide) chelator ((ArO)-Ar-Ad)(3)N3-. Reaction of an appropriate uranium precursor, either the boolean OR(III) starting material, [(((ArO)-Ar-Ad)(3)N)boolean OR(DME)], or the dinuclear monochalcogenido-bridged uranium(IV/IV) compounds [{(((ArO)-Ar-Ad)(3)N)boolean OR(DME)}(2)(mu-E)1 (E = S. Se), with elemental sulfur or selenium, yields new complexes with a variety of bridging chalcogenide entities mu-E-m(n-) (E = S. m = 2, n = 1 or 2 and E = Se, m = 2, 4; n = 2). Activation of the heavy chalcogens typically requires either a coordinatively unsaturated, strongly-reducing metal complex or a compound with a metal-metal bond. Since uranium complexes in the +IV oxidation state, are generally considered rather unreactive, the observed reaction of the here employed uranium(IV)/(IV) species with elemental chalcogens is fairly remarkable.