Radical catalysis of enzymatic and biomimetic polynuclear transition-metal active sites

Radicals generated by redox-active transition metal centers appear crucial for many vital and difficult biochemical transformations. In this proposal, we will focus on polynuclear transition-metal active sites, mostly in radical S-adenosylmethionine (SAM) enzymes, and thein electronic-structure contributions to redox reactivity. These species are important not only for their functions in nature but also represent challenging systems for both experimental and theoretical chemistry. By means of a gamut of theoretical methods, first calibrated on a set of structurally and electrochemically well-defined representative systems and later correlated with the relevant spectroscopic and electrochemical data, key radical SAM intermediates responsible for radical-mediated attack of diverse substrates will be investigated along with their effects on H-atom abstraction selectivity and radical propagation to the substrate. The results are expected to contribute to understanding of the general factors that control selective mechanisms in the realm of powerful radical enzymes.