Synthetic, Mechanistic, and Catalytic f-Element Organometallic Chemistry

Northwestern University, Evanston IL

Investigators

Abstract

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Dr. Tobin J. Marks at Northwestern University to investigate fundamental aspects of new catalytic transformations involving lanthanide and related early transition metals. The strengths of bonds being made and broken in organometallic/catalytic processes will be quantified. Reaction calorimetry will be used to quantify the strengths of metal-ligand multiple bonds, of metal-main group ligand single bonds, and to "anchor" the data on an absolute scale. This fundamental scientific information will then used to: elucidate bonding, rationalize known reaction patterns, and develop principles for the invention of new, useful catalytic processes. New catalytic mechanisms will be investigated pertaining to transformations in which element-H bonds are added to unsaturated carbon-carbon bonds (hydroelementation) to selectively create heteroatom- containing organic molecules. The primary focus is on selective C-N, C-P, C-B, and C-S bond-forming processes, studying a range of precursor structures (C=C, C=C=C, C=C-C=C), characterizing rates, selectivities, substituent effects, and comparing intramolecular vs. intermolecular processes. Catalytic cascades in which controlled sequences of coupled bond-forming processes (e.g., C-N + C-C) take place at single and proximate metal centers will also be studied and refined as ultimate routes to useful fine chemicals and bio-active molecules, as well as to establish new catalytic principles. Organolanthanide-catalyzed polymerization processes will be investigated that involve single or closely poised multiple metal centers coupled to element-H/metal-C exchange processes or to hydroelementation processes that produce new types of polymer chains "end-capped" with a heteroatom (e.g., Si, Sn, B, Al). The properties of chiral complexes having various symmetry environments will be studied with respect to structure, stability, and efficacy in enantioselective variants of catalytic transformations. Unusual chelating ligand structures having sulfur and phosphorus donor atoms will also be studied. In addition, actinide complexes will be investigated to compare/contrast electronic structure effects on catalytic properties. This project focuses on organometallic/catalytic/materials chemistry in order to effect, characterize, understand, and disseminate to the community, unusual and potentially useful new stoichiometric and catalytic reactivity principles applicable to making more efficient, atom- economical catalytic processes for the production of fuels, plastics, pharmaceuticals, and other economically important chemicals. Participation in this multifaceted/multidisciplinary project, including interactions with industrial scientists, will prepare graduate, undergraduate, and postdoctoral students, having diverse backgrounds, for productive careers in industry, government laboratories, and academe.