Hydrogen Atom Transfer Reactivity of Unsymmetric Bimetallic Complex

With support from the Chemical Structure, Dynamics & Mechanisms-B Program (CSDM-B) and the Chemical Synthesis (SYN) Program of the Chemistry Division, Shiyu Zhang of the Department of Chemistry at Ohio State University is developing model complexes to elucidate the influence of inequivalent environment on the reactivity of bimetallic centers in natural proteins. The goal of this research is to bridge the gap between metalloenzymes and synthetic catalysts designed to mimic enzymatic functions and unveil new design strategies for catalysts fundamental to energy, health, and environmental science. The research activities will be integrated with the training of undergraduate and graduate students in addressing interdisciplinary challenges with a combination of synthetic inorganic, spectroscopic, and theoretical methods. Outreach activities involving K-12 students will also be part of the funded project. In this project, two classes of new bimetallic complexes will be prepared to reproduce ubiquitous unsymmetric features of bimetallic active sites in nature, e.g., (i) inequivalent secondary coordination sphere, (ii) inequivalent primary coordination sphere, and (iii) unsymmetric metal binding (heterobimetallic center). New methods will be developed to quantify the degree of bimetallic differentiation and establish a set of metrics (hydrogen atom transfer kinetics, metal affinity, etc.) to help define success with the goal of improving our understanding of the metalloenzymes of interest. In Aim 1, dicopper model complexes with inequivalent features at the primary and secondary coordination sphere will be synthesized to understand if the degree of site-differentiation correlates with the rate of hydrogen atom transfer. In Aim 2, biomimetic heterobimetallic FeMn complexes will be developed to understand the formation of synthetic FeMn complexes. The reactivity of isostructural FeMn, FeFe, and MnMn bimetallic complexes toward oxygen activation and hydrogen atom transfer will be compared to understand the evolutionary implications of heterobimetallic active sites. 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.