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)2U–H]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)2UMe2 (4) with 2 equiv of phenylsilane at 50 °C. The U­(III) system is a potent reducing agent and displayed chemistry distinct from the U­(IV) system [(C5Me5)2U­(H)­(μ-H)]2 (2), which was harnessed to prepare a variety of organometallic complexes, including (C5Me5)2U­(dmpe)­(H) (6), and the novel uranium­(IV) metallacyclopentadiene complex (C5Me5)2U­(C4Me4) (11).