Gold(I) Complexes Containing Unsaturated Hydrocarbyl Ligands

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In this project funded by the Chemical Structure, Dynamics and Mechanisms B Program of the Chemistry Division, Professor Ross A. Widenhoefer in the Department of Chemistry at Duke University will investigate new chemistry of neutral gold(I) complexes. The project focuses on unsaturated hydrocarbyl ligands including sigma-alkenyl, -allyl, -allenyl, and -propargyl ligands. One goal of this research is to develop a meaningful understanding of the structures and fluxional behavior of these complexes and, likewise an understanding of the mechanisms through which these complexes undergo electrophilic deauration (loss of gold). In doing so, these activities will provide mechanistic insight that will serve the ever growing global community of researchers working toward (1) the development of new and more efficient gold(I) catalyzed transformations and (2) elucidation of the mechanisms of gold(I)-catalyzed transformations. The proposed research activities are fully integrated into the scientific education and training of the graduate and undergraduate student researchers, including students from ethnic groups traditionally underrepresented in the sciences. Graduate students are encouraged to augment their graduate research and educational experience through participation in educational activities offered through the Duke University Graduate School. Graduate students will participate in community outreach activities in collaboration with Dr. Ben Bobay of the Duke NMR center, directed toward providing local high school students with hands-on exposure to modern high-field NMR spectroscopy and one-on-one instruction in the processing, manipulation, and interpretation of NMR data.Despite a growing body of research in this area, limited experimental information is available regarding the structure, reactivity, and fluxional behavior of gold complexes containing unsaturated hydrocarbyl ligands including sigma-alkenyl, -allyl, -allenyl, and -propargyl ligands. The proposed research activities aim to fill these gaps and develop an experimentally-grounded understanding of gold complexes containing unsaturated hydrocarbyl ligands. Focus is on understanding the structure and fluxional behavior of these complexes and the mechanisms of electrophilic deauration. The research will address two areas of inquiry. The first area involves the elucidation of the mechanisms for the addition of electrophiles to gold alkenyl complexes involving direct attack on the C=C alkenyl bond by (i) validating the pi-alpha pathway for electrophilic addition, (ii) validating the pi-beta pathway for electrophilic addition, and (iii) modeling the transition state/intermediate for alkyne/alkene cycloaddition. The second area involves the elucidation of the structures, fluxional behavior and nucleophilic behavior of gold hydrocarbyl complexes possessing beta, gamma and or gamma, delta unsaturation, specifically targeting (i) gold sigma-allyl complexes, (ii) gold sigma-allenyl and sigma-propargyl complexes, and (iii) gold 3-butenyl complexes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.