Synthesis and Reactivity of Metallaradicals

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The focus of this project in the Inorganic, Bioinorganic and Organometallic Chemistry Program is the preparation of new organometallic compounds which contain unpaired electrons. The new compounds are expected to include some which are useful as catalysts for the oxidation of organic molecules. Chromium(III) alkylidenes will be prepared by deprotonation of cationic alkyl precursors. Full characterization and elucidation of their reactivity will be pursued in parallel to their application in ring opening metathesis polymerization of functionalized olefins. The preparation of alkyls of chromium(II) and chromium(IV), and of paramagnetic chromium hydrides, will be attempted also, and the reactivities of these new compounds toward insertion of small unsaturated molecules into the carbon-chromium bond will be explored. Previous work in the area of cobalt(IV) and cobalt(V) alkyls will be extended to new alkyl groups and new coordination geometries. For example, stabilization of these high oxidation states by coordination to the pentamethylcyclopentadienyl ligand will be explored. Another extension will aim at the preparation of tetrahedral cobalt oxo complexes, which would be used in oxidations of organic substrates. Tris(pyrazolyl)borate ligands will be utilized to stabilize high-valent cobalt in an attempt to develop oxygenation catalysts which utilize dioxygen.