Advancing Late Metal Catalysis: DalPhos Ligand Design, Mechanism, and New Reactivity

Metal-based catalysts play a central role in promoting chemical reactions that give rise to the molecules and materials that we make use of in our everyday lives (e.g. fuels, plastics, medicines, and other). In this regard, the development of new classes of catalysts that allow for the conversion of cheap and abundant reagent molecules into value-added products of interest represents an important and ongoing challenge in modern academic and industrial research. Of particular interest is the identification of catalysts that enable useful chemical transformations that are not currently possible by any other means. This proposal targets the rational development of new classes of metal-based catalysts to enable extremely challenging reactions that convert cheap and abundant small-molecules, including ammonia, hydrazine, and hydroxylamine, into useful products in an efficient and more environmentally friendly manner, with direct applications in the preparation of pharmaceuticals and next-generation power-generating devices. The metal-based catalysts under investigation build upon what are now commercialized “DalPhos” (DALhousie PHOSphine) ligands developed in the applicant’s research group; these exhibit remarkable catalytic behavior that is distinct from most other known catalyst types, but our understanding of this behavior is very limited. In response, we will seek to harness and augment the unique behavior of DalPhos-based metal catalysts via strategic diversification/optimization of the DalPhos ligand structure followed by catalyst screening, with the goal of obtaining optimized structures that we can study in detail regarding their mode of action. Optimized DalPhos catalysts will then be applied toward addressing the challenging reactivity types listed above. The proposed synthetic, structural, mechanistic, and catalytic studies will expand our conceptual understanding of ligation effects in metal-catalyzed reactions, as well as providing practical in-roads to new medicines and functional materials.