Polynuclear active sites are a common motif employed by enzymes to facilitate cooperative redox chemistry. For instance, diiron enzymes serve a variety of purposes in nature; examples include soluble methane monooxygenase (sMMO), an enzyme that promotes catalytic hydroxylation of organic substrates, and ribonucleotide reductase (RNR), which activates dioxygen in the conversion of ribonucleotides to the corresponding deoxyribonucleotides. Inspired by the cooperativity of these and similar enzymes, we aim to derive a functional mimic utilizing a bimetallic scaffold that promotes metal–metal interaction and the stabilization of reactive intermediates. Specifically, we propose the use of dipyrrinato pacman structures, wherein the bimetallic architecture can support two metals proximally oriented to maximize their ability to perform cooperative chemistry. To this end, we explored the ability of this system to stabilize bridging oxide and hydroxide species in an analogous fashion to the reactive intermediates observed in active sites, synthesizing a series of diiron <i>µ</i>-hydroxide and <i>µ</i>-oxide complexes and studying their interconversion. Extension of the dipyrrin pacman system to support other functionalities, including bridging imido, sulfide, and hydride complexes that can serve as functional mimics to other classes of enzymes, are current targets to allow us to gain further insight into how the nature of the bridging ligand affects metal–metal cooperativity and subsequent reactivity.

Exploring cooperative redox chemistry using dipyrrin pacman complexes

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.