Cationic Gold-Antimony Complexes: Synthesis and Electrophilic Properties
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abstract
A catalyst is a substance that speeds or otherwise facilitates a chemical reaction. Catalysts are critical to the chemical and pharmaceutical industries, where they are used to reduce the energy required for chemical reactions and to guide the details of precise chemical transformations. While gold is an expensive element, many catalysts incorporate it. Improving gold catalysts is an important area of investigation. In this project, funded by the Chemical Synthesis Program of the Chemistry Division, Professor Francois Gabbai of the Department of Chemistry at Texas A&M University seeks to improve the catalytic properties of gold by combining it with antimony, a non-metallic element. The antimony is able to combine with gold in a way that enhances gold''s reactivity. The gold-antimony compounds that are isolated are developed into catalysts for the activation of alkenes, which are major chemical industry feedstocks. Professor Gabbai participates in outreach programs to K-6 students in Spanish/English dual language programs in order to interest young students in science and technology. This research project investigates the chemistry of gold (Au) complexes featuring ambiphilic ligands comprised of two phosphine donors and an antimony moiety. The central objective is to determine if the charge of the antimony (Sb) ligand can be used to modulate the electrophilic character and catalytic properties of the gold center. A series of dinuclear complexes with a gold atom held in close proximity to a pentavalent antimony center are synthesized and ligand abstraction reactions generate complexes in which the pentavalent antimony center is either monocationic or dicationic. Structural, spectroscopic and computational studies indicate if the accumulation of positive character on the antimony ligand promotes a donor-acceptor Au-Sb interaction. A correlation between the charge of the antimony ligand and the electrophilic reactivity of the gold center is indicated by the catalytic activation of alkenes in polymerization and hydroamination reactions. 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.
