The syntheses of a number of (η5-C5H5)3ThR organometallics from (η-C5H5)3ThCl and the corresponding RLi or RMgX reagents are reported. The new compounds have been characterized by chemical means, and by infrared, laser Raman, and proton NMR spectroscopy. The properties of these thorium organometallics are compared to those of the analogous (C5H5)3UR compounds. With both elements the (C5H53M(allyl) species is a fluxional η1-allyl; the barriers to sigmatropic rearrangement are comparable. The Th-C bond reacts more readily with protonic solvents. The (C5H5)3ThR compounds are more thermally stable in solution. The thermolysis pathway is similar to uranium, with intramolecular extrusion of R-H taking place (H derived from a cyclopentadienyl ring) rather than olefin elimination. For thorium, the other product of thermolysis is (η5-C5h5)2Th(η1:η5-C5H5)2Th(η5-C5H5)2 which appears to arise via an intermediate η1-C5H4 carbene complex-ylide. Coordinative saturation and 5f electron configuration play an important role in directing the course of certain types of reactions of organoactinides.
ASJC Scopus subject areas
- Colloid and Surface Chemistry