Event

Title Synthetic single-site iron nitrogenases

Abstract: Nitrogen reduction to NH3 is a requisite transformation for life. While it is widely appreciated that the Fe-rich cofactors of nitrogenase enzymes facilitate this transformation, how they do so remains poorly understood. A central element of debate has been the site(s) of dinitrogen coordination and reduction. The synthetic inorganic community placed an early emphasis on Mo because Mo was thought to be an essential element of nitrogenases, and because pioneering work had established that well-defined Mo model complexes could mediate the stoichiometric conversion of coordinated N2 to NH3, ultimately leading to the development of catalytic systems.

  It is known, however, that Fe is the only transition metal essential to all nitrogenases, and recent biochemical and spectroscopic data have implicated Fe as the likely site of N2 binding in FeMo-co. These observations motivated a search for functional Fe catalysts, examples of which were discovered by our lab several years ago. I will discuss our latest progress on Fe complexes that catalyze the reduction of N2 to NH3. Our most recent efforts have targeted improving the efficiency of synthetic Fe nitrogenases via exploring alternative conditions and catalyst scaffolds, and using experiment and theory to better understand the mechanisms by which these Fe catalysts function. Our long-term goal is to use this understanding to couple solar water-splitting devices with ammonia synthesis catalysts, akin to related approaches for the generation of solar fuels.

Inquiries please contact Rosa M. Vargas rvargas@sas.upenn.edu