CAREER: Combined Experimental and Computational Approach to Controlling Site Selectivity in Cross Coupling Chemical Reactions

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Cross couplings are a type of chemical reaction in which two different molecules are joined together by a metal catalyst. These reactions are valuable for forming carbon-carbon, carbon-nitrogen, and other types of bonds for the construction of complex organic molecules for use in drug design, the design of new biomaterials, and other advanced manufacturing applications. In cross coupling reactions the control of reaction selectivity is often challenging. If the catalyst cannot differentiate between several possible reaction sites on the molecules, a mixture of products will result. Purification of that mixture increases cost and waste. In this project, Dr. Neufeldt is developing catalysts for cross coupling that efficiently differentiate between similar reactive sites. Both laboratory-based and computational studies are being employed to understand how the catalyst structure influences the way the catalyst interacts with subtly different sites. This information is being used to design improved catalysts to achieve higher selectivity and efficiency. As part of this project, Dr. Neufeldt is involved in activities to encourage participation of underrepresented minorities in scientific research and improve computational chemistry education at the undergraduate level. These activities include involving students from neighboring tribal colleges in computational chemistry research, implementing computational chemistry labs into the organic curriculum at Montana State University, and engaging in outreach to local schools and tribal colleges. Dr. Neufeldt is identifying and exploiting new mechanisms by which phosphine and N-heterocyclic carbene (NHC) ligands can influence site selectivity in nickel (Ni)- and palladium (Pd)-catalyzed cross coupling reactions. Phosphine ligands are being studied for their ability to control selectivity between phenol derivatives and chlorides in Ni-catalyzed cross couplings. In addition, NHC ligands are under investigation for their ability to influence selectivity between aryl triflates and chlorides in Pd-catalyzed couplings. The origin of selectivity in these systems is examined through a combination of experimental and computational studies. Density functional theory is also employed to design new site-selective catalysts on the computer. The work in this project is valuable for improving the functional group tolerance of cross couplings, facilitating sequential or iterative couplings, and providing insight into catalyst structure-selectivity relationships. The broader impacts of this project include engaging American Indian students in research in science, technology, engineering, and mathematics (STEM) disciplines, as well as introducing students of diverse ages to computational chemistry.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.