Ligand Design to Control the Energetics of Transition Metal Mediated Reactions for Hydrocarbon Functionalization that Involve Redox Changes

With the support of the Chemical Catalysis Program and the Chemical Mechanism, Function, and Properties Program of the Division of Chemistry, Professor T. Brent Gunnoe of the Chemistry Department at the University of Virginia is studying the development of new catalysts for hydrocarbon functionalization, which enables conversion of chemicals derived from natural gas and petroleum into higher value products. Current methods for hydrocarbon functionalization typically involve multi-step and energy-intensive processes. New catalysts that provide more direct and efficient routes for hydrocarbon functionalization can advance the chemical and energy sectors. While there are opportunities to increase energy efficiency of large-scale chemical processes, there are also substantial scientific challenges. In this project, Professor Gunnoe's group will develop new understanding of how to perform selective and energy-efficient catalytic chemical transformations that are essential to the goal of using natural gas and other fossil resources in a more energy-efficient manner. Catalytic small molecule functionalization using molecular transition metal complexes often involves catalytic cycles that feature changes in the formal oxidation state of the metal. It is common that proposed catalytic cycles involve a transition metal catalyst that mediates a series of bond-breaking and bond-forming steps while cycling through at least two different redox states. Hence, kinetic access to multiple oxidation states is critical to rapid catalysis. However, accessing multiple formal oxidation states can be particularly problematic for catalytic hydrocarbon functionalization reactions using low valent metals for C–H bond-breaking under conditions that include an oxidant, because the presence of an oxidant can lead to formation of more stable, higher valent redox state(s). The research effort will focus on three objectives. Objective 1. Understand the impact of capping arene ligands on hydrocarbon activation and functionalization reactions that involve redox changes at the transition metal. Objective 2. Understand and develop hydrocarbon activation and functionalization with bifunctional Cu complexes. Objective 3. Understand and develop new small molecule activation with bifunctional second and third row transition metal complexes. 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.