Tuning the Oxidation State, Nuclearity, and Chemistry of Uranium Hydrides with Phenylsilane and Temperature: The Case of the Classic Uranium(III) Hydride Complex [(C5Me5)2U(μ-H)]2

This work demonstrates that the oxidation state and chemistry of uranium hydrides can be tuned with temperature and the stoichiometry of phenylsilane. The trivalent uranium hydride [(C5Me5)(2)UH](x) (5) was found to be comprised of an equilibrium mixture of U(III) hydrides in solution at ambient temperature. A single U(III) species can be selectively prepared by treating (C5Me5)(2)UMe2 (4) with 2 equiv of phenylsilane at 50 degrees C. The U(III) system is a potent reducing agent and displayed chemistry distinct from the U(IV) system [(C5Me5)(2)U(H)(-H)](2) (2), which was harnessed to prepare a variety of organometallic complexes, including (C5Me5)(2)U(dmpe)(H) (6), and the novel uranium(IV) metallacyclopentadiene complex (C5Me5)(2)U(C4Me4) (11)