This project is directed toward the syntheses and study of cationic, 14-electron gold(I) pi-alkene, pi-allene, and pi-alkyne complexes. Cationic gold(I) complexes have recently emerged as effective catalysts for the functionalization of C-C multiple bonds with carbon and heteroatom nucleophiles. However, the cationic, two-coordinate gold(I) pi-complexes germane to catalysis remain scarce and, as a result, little is known about the structure and reactivity of these important complexes. Execution of the proposed research activities will fill this gap in our understanding. Studies directed toward realizing this objective include analysis of 1) the ground-state structure and fluxional behavior of cationic gold(I) pi-complexes, 2) the relative binding ability pi-hydrocarbyl ligands to a cationic gold fragment, 3) the kinetics of degenerative ligand exchange of cationic gold(I) pi-complexes, and 4) the reactivity of gold pi-complexes toward nucleophiles.
With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Professor Ross Widenhoefer of the Department of Chemistry at Duke University. Professor Widenhoefer's research efforts are directed, in large part, to the mechanistic analysis of the gold(I)-catalyzed addition of carbon and heteroatom nucleophiles to alkenes and allenes. Realization of the proposed activities will provide mechanistic information valuable to the ever-growing global community of researchers working toward the development of new and more efficient gold(I) catalyzed transformations for application in organic synthesis and pharmaceutical development.
One of the most important developments in homogenous catalysis over the past decade has been the significant growth in the application of cationic gold(I) complexes as catalysts for organic transformations with potential applications in pharmaceutical development and target-oriented synthesis. As is often the case in homogeneous catalysis, an understanding of the mechanisms of gold catalysis has lagged significantly behind the synthetic development of this chemistry and this lack of understanding represents a significant impediment to the continued development of these methods. For this reason, our research activities during the tenure of this grant were directed toward the synthesis and study of gold π-complexes that have been widely invoked as intermediates in gold-catalyzed transformation. Specifically we synthesized cationic, two-coordinate gold complexes that contained a p-alkene, allene, alkyne, or diene ligand, we characterized these complexes in solution and the solid state, and we investigated the intermolecular and intramolecular exchange processes germane to catalysis. The intellectual merit of the research activities conducted during the tenure of this grant is two-fold. Firstly, our results have contributed in a meaningful way to the broader understanding of the structure and reactivity of transition metal π-complexes. Secondly, our results provide mechanistic insight that will serve the ever growing community of researchers working toward the development of new and more efficient gold(I) catalyzed transformations. The broader impacts resulting from the proposed activities stem from the integration of scientific discovery with the training and education of undergraduate, graduate, and postdoctoral researchers. Specifically, the research activities conducted during the tenure of this grant were fully integrated with the scientific education of the students who conducted the research and these research activities included participation of both female students and students from ethnic groups traditionally underrepresented in the sciences.
