Transition metal catalyzed hydrogenation of carbon dioxide to carbon-based fuels and feedstocks like formic acid and methanol has been an important topic of research in recent years. This presentation will discuss studies of a new type of bifunctional catalysts for hydrogenation of CO2. These catalysts are transition metal phosphine complexes in which one of the phosphine ligands contains a redox active group capable of mediating hydride transfer and is therefore referred to as a hydride relay. These hydride relays are designed to minimize kinetic and thermodynamic barriers for H2 activation and substrate reduction. A series of these complexes has been synthesized and characterized based on a simple and modular synthetic design using different redox active groups that have varying hydride donor abilities. Metal complexes have been synthesized using inexpensive first row transition metal like Ni and the precious metals Pd, Rh, and Ru. The synthesis and characterization of these complexes, as well as their catalytic activity for hydrogenation of CO2, will be discussed. One complex in particular, a ruthenium complex containing a benzimidazolium relay, was found to be catalytically active for the hydrogenation of CO2 even at very low pressures and temperatures. Studies of the catalytic activity of this complex, including the role of the relay as well as the role of solvent and base will be discussed.

Development of bifunctional catalysts containing hydride-relay ligands for CO2 hydrogenation

255th National Meeting (2018)

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