Dr. Tobin J. Marks, Department of Chemistry, Northwestern University, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division for a study of the organometallic chemistry of the f-elements (actinides and lanthanides), and closely related early transition metals. The goal of the project is to design, characterize, and understand from a structural, mechanistic, and thermodynamic sense novel stoichiometric and catalytic transformations involving f-element organometallic molecules. The project consists of four closely interconnected components:(1) Titration calorimetry will be utilized to quantify the strengths of metal-ligand multiple bonds, of bonds involving `zero-valent` f-element complexes, of bonds involving heavier groups 14-16 ligands, and to firmly `anchor` existing bond energy data compilations on an absolute scale; (2) The scope and mechanism of organolanthanide/organoactinide-catalyzed reactions in which element-H bonds are added to unsaturated carbon-carbon bonds will be determined, with focus being concentrated on thermodynamic feasible hydroamination, hydrophosphination, hydroboration, and hydrothiolation reactions; (3) The properties of chiral lanthanide and actinide complexes having C1 symmetric ligation will be investigated with respect to structure, stereochemical integrity, and efficacy in enantioselective catalytic transformations of the types described in (2); and (4) organolanthanide-catalyzed chain transfer reactions in which olefin polymerization is coupled to element-H/metal-C transposition processes will utilized to produce a series of heteroatom `end-capped` polyolefins, and unusual polyolefins in which methylene units are directly appended to polymer backbones. Transformations involving organometallic compounds are of central importance to numerous areas of U.S. industrial chemistry, including catalytic processes for the production of fuels, polymeric materials, pharmaceuticals, and other economically important chemicals. Developments in this area are crucial to the development of ever more efficient, selective, environmentally benign, and economically competitive process technologies. This project focuses on the lanthanides and actinides. The organometallic chemistry of these elements has until recently been relatively unexplored, and there is growing interest in their application in polymerization catalysis and organic synthesis. The goal of this project is to effect, characterize, and understand unusual and potentially useful transformations involving f-element organometallic molecules.
