U(IV) Chalcogenolates Synthesized via Oxidation of Uranium Metal by Dichalcogenides

Treatment of uranium metal with dichalcogenides in the presence of a catalytic amount of iodine in pyridine affords
molecular U(IV) chalcogenolates that do not require stabilizing ancillary ligands. Oxidation of U0 by PhEEPh yields
monomeric seven-coordinate U(EPh)4(py)3 (E = S(1), Se(2)). The dimeric eight-coordinate complexes [U(EPh)2(μ2-EPh)2(CH3CN)2]2 (E = S(3), Se(4)) are obtained by crystallization from solutions of 1 and 2 dissolved in acetonitrile.
Oxidation of U0 by pySSpy and crystallization from thf yields nine-coordinate U(Spy)4(thf) (5). Incorporation of
elemental selenium into the oxidation of U0 by PhSeSePh results in the isolation of [U(py)2(SePh)(μ3-Se)(μ2-SePh)]4·4py (6), a tetrameric cluster in which each U(IV) ion is eight-coordinate and the U4Se4 core forms a
distorted cube. The compounds were analyzed spectroscopically and the single-crystal X-ray structures of 1 and
3−6 were determined. The isolation of 1−6 represents six new examples of actinide chalcogenolates and allows
insight into the nature of “hard” actinide ion−”soft” chalcogen donor interactions.