Abundant transition metals in catalysis

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Our program will focus on the discovery of new catalysts based on the sustainable metals manganese, cobalt and iron. Industry is striving to replace catalysts based on platinum group metals that are precious and rare with these more abundant metals that are cheaper, more benign to human health and more appropriate for green chemical processes. Our catalysts will allow effective and new syntheses of amines of importance in making pharmaceuticals, agrochemicals and polymers, and alcohols with applications in pharma, fragrances and green energy storage. In the past five years we developed state-of-the-art catalysts (the FeATHerII and FeATHerIII catalysts) for asymmetric transfer hydrogenation (ATH) of ketones and certain imines, and more recently for the asymmetric pressure hydrogenation of ketones using iron and manganese. With this success, my research team has grown to eleven graduate students, 8 domestic and 3 co-supervised (U. Muenster), along with visitors and undergraduates a powerful catalyst discovery team. We will use our proven experimental and computational approaches to discover new catalysts that are easier and safer to synthesize, more active, productive and selective and more robust with respect to oxygen and deactivation routes. Like enzymes, our catalysts will be designed with complementary groups on the ligand to those of imines and ketones to dramatically improve catalytic enantioselectivity in the production of alcohols and amines of value to the pharmaceutical and fine chemical industries. We will use our skill in ligand synthesis and computational modelling to build in hydrogen bond donors and acceptors using established methods. Our phosphine aldehyde precursors are an ideal starting point for this chemistry. These new metal complexes will be applied to a variety of important asymmetric reactions in organic synthesis including hydrosilylation, hydroboration and carbon-carbon bond forming. A more recent feature is the use of N-heterocyclic carbene donors tethered with primary or secondary amines (e.g. enantiopure Kaibene discovered by graduate student Kai Wan) that provide a real boost in activity. Our ligand acidity constant (LAC) equation that was first described in 2014 for predicting the acidity of hydride and dihydrogen complexes has significant implications for catalyst design. It will be used to explore and guide the synthesis of catalysts that are tolerant to the acidic conditions of carbon dioxide reduction to liquid fuels and imine hydrogenation. We will measure the acidity of paramagnetic metal hydride complexes and use state of the art computational tools to understand the factors that determine their acidity. To assist in the hot field of catalytic carbon-hydrogen bond functionalization we will extend the LAC concepts both experimentally and computationally to coordinated (agostic) carbon-hydrogen bonds.