Observations on the thermal decomposition of some uranium(IV) tetraalkyls

The thermally unstable products of the reactions 4 RLi + UCl₄ (R = various alkyl groups), presumed to be uranium tetraalkyls, decompose readily at room temperature in ethereal or hydrocarbon solvents. When R contains a β-hydrogen, comparable quantities of alkane (RH) and alkene (RH-H₂) are produced along with trace amounts of the dimer, RR. This result indicates that uranium alkyl compounds readily decompose via β-hydrogen elimination under the appropriate circumstances (coordinative unsaturation). When a β-hydrogen is not present, the alkane, RH, is the major product. That stereochemistry is retained at the α-carbon atom of the 2-cis- and 2-trans-2-butenyl compounds suggests that 2-butenes are not formed from free R^- radicals.