Abstract

FeMoco has long been, and continues to be, an enigmatic cluster. Over 8 years ago the presence of a carbide in the cluster was first revealed. However, the role of the carbide, the role of the Mo heterometal, and the changes which occur at the seven iron sites during the course of catalysis all remain open questions. Herein, we present studies of selenium incorporated FeMoco. High-energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD XAS) at the Se K-edge is utilized to obtain selective information about the electronic structure of FeMoco. These studies reveal a significant asymmetry in the electron distribution within FeMoco, suggesting a much more localized electronic structure than typically assumed for iron sulfur clusters. Further XAS studies of both natively reduced and cryoreduced MoFe protein will be presented. These studies are essential for establishing the nature of the first redox event in the catalytic cycle of nitrogenase.  Together, these studies form a basis for unravelling the electronic structural details of this complex catalytic process.

Biography

Serena DeBeer is a Professor and Director at the Max Planck Institute for Chemical Energy Conversion in Mülheim an der Ruhr, Germany. She is also an Adjunct Professor in the Department of Chemistry and Chemical Biology at Cornell University, an honorary faculty member at Ruhr University in Bochum, and the group leader of the PINK Beamline at the Energy Materials In‐Situ Laboratory at Helmholtz Zentrum in Berlin. She received her B.S. in Chemistry at Southwestern University in 1995 and her Ph.D. from Stanford University in 2002. From 2002-2009, she was a staff scientist at the Stanford Synchrotron Radiation Laboratory, before moving to her faculty position at Cornell. She is the recipient of a European Research Council Synergy Award (2019), the American Chemical Society Inorganic Chemistry Lectureship Award (2016), the Society of Biological Inorganic Chemistry Early Career Award (2015), a European Research Council Consolidator Award (2013), a Kavli Fellowship (2012), and an Alfred P. Sloan Research Fellowship (2011). Research in the DeBeer group is foucsed on the development and application of advanced X-ray spectroscopic tools for understanding key mechanisms in biological, homogeneous and heterogeneous catalysis.