Expanding f element chemistry: Reactivity of yttrium, lanthanide, and actinide metal complexes with diazoalkane derivatives and guanidinates.

摘要

This dissertation develops f element chemistry by investigating and comparing the synthesis, coordination chemistry, and reactivity of lanthanide and actinide metal complexes with diazoalkane derivatives and guanidinates. The bis(cyclopentadienyl) ligand unit, [(eta5-C5Me5)2] 2-, was used to conduct these studies since it has previously proven to be a reliable route for investigating new ligands in f element chemistry. This is because it is relatively inert, provides solubility and stability to the reactive metal center, and allows spectroscopic and structural data to be obtained that is useful for analyzing this chemistry.Diazoalkanes, RR'CN2, are of interest because they are important organic substrates that are useful as carbene precursors and as reagents for the synthesis of heterocyclic compounds. Although the chemistry of diazoalkanes with the transition metals has been heavily studied, little is known about f element chemistry with these compounds. The lanthanides and actinides are different in their behavior with diazoalkanes. Lanthanides make cyanoamide complexes that can be converted by their reaction with nitriles to complexes of 1,2,3-triazoles, which are heterocycles with pharmaceutical, industrial, and agrochemical applications. In contrast, uranium makes very soluble products that do not react with nitriles. A facile synthetic route to hydrazonato complexes was also developed from lanthanide allyl complexes and diazoalkanes during this study.The chemistry of the bicyclic guanidinate ligand, (hpp)1-, was examined with the f elements because this ligand has the potential to stabilize higher oxidation states which are rare with the f elements. The (hpp)1- ligand can be readily incorporated into complexes of Ln3+, U3+, and U4+ and it can stabilize rare examples of mono-alkyl, hydride, and "tuck-in", (eta5:eta1 -C5Me4CH2)2- U 4+ complexes as well as U5+ in some cases. The reactivity of the uranium "tuck-in" complex was examined because this unit is frequently proposed as an intermediate in mechanistic schemes involving alkyl C-H bond activation with the f elements. The effect of the {(C5Me5 )2(hpp)}3- ligand combination on uranium mono-alkyl and hydride reactivity was also examined. Altogether, the results from these studies expand our knowledge of f element chemistry and highlight the differences in chemical reactivity of the f elements compared to the transition metals.