Solvent-Free Organometallic Reactivity: Synthesis of Hydride and Carboxylate Complexes of Uranium and Yttrium from Gas/Solid Reactions

Gas/solid reactions involving H₂ and CO₂ with the metallocenes (C₅Me₅)₂UMe₂ and (C₅Me₅)₂U­(allyl)₂ as solids in the absence of solvent provide an improved method to make organouranium hydride and carboxylate products. Decomposition products that can form in solution from the reactive hydrides can be avoided by this method, and this approach can also provide intermediates too reactive to isolate in some solution reactions. In contrast to the variable nature of the hydrogenolysis reaction of (C₅Me₅)₂UMe₂ in toluene that forms byproducts along with the mixture of [(C₅Me₅)₂UH₂]₂ and [(C₅Me₅)₂UH]₂, a byproduct-free hydrogenolysis occurs when (C₅Me₅)₂UMe₂ in the solid state is treated with H₂ gas to form predominantly [(C₅Me₅)₂UH₂]₂. H₂ reacts with solid (C₅Me₅)₂U­(C₃H₅)₂ and (C₅Me₅)₂U­(C₃H₅) similarly. The reaction of CO₂ (80 psi) with solid (C₅Me₅)₂UMe₂ forms the monocarboxylate (C₅Me₅)₂U­(O₂CCH₃-κ²<i>O</i>,<i>O</i>′)­Me, in contrast to the solution reaction that forms the diacetate (C₅Me₅)₂U­(O₂CCH₃-κ²<i>O</i>,<i>O</i>′)₂ in minutes. The reaction of H₂ with solid (C₅Me₅)₂Y­(C₃H₅) provided (C₅Me₅)₂Y­(μ-H)­YH­(C₅Me₅)₂ without the decomposition products that it forms in solution such that single crystals suitable for X-ray diffraction could be isolated for the first time