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 U-0 by PhEEPh yields monomeric seven-coordinate U(EPh)(4)(py)(3) (E = S(1), Se(2)). The dimeric eight-coordinate complexes [U(EPh)(2)(mu(2)-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 U-0 by pySSpy and crystallization from thf yields nine-coordinate U(Spy)(4)(thf) (5). Incorporation of elemental selenium into the oxidation of U-0 by PhSeSePh results in the isolation of [U(py)(2)(SePh)(mu(3)- Se)(mu(2)-SePh)](4)center dot 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.