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-κ2O,O′)­Me, in contrast
to the solution reaction that forms the diacetate (C5Me5)2U­(O2CCH3-κ2O,O′)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.