Many of the essential redox processes in biology take place at multimetallic cofactors embedded within the active sites of proteins. Examples include the NiFe and FeFe hydrogenases that reversibly interconvert protons and dihydrogen; the Fe- and Cu-based methane monooxygenases that selectively oxidize methane to MeOH; and the NiFe and MoFe CO dehydrogenases that fix CO2, enabling its use as a C1 source in biosynthesis. Across these diverse enzyme classes, a common theme is the remarkable use of cooperativity between two or more transition metals as a means of activating challenging substrates. This multifunctionality presents a striking contrast to the most prominent synthetic transition metal catalysts, a majority of which rely on a single metal ion to mediate all of the necessary redox processes and bond rearrangements. In this seminar, we present our recent efforts toward the development of generalizable catalytic platforms containing metal–metal bonds as active sites. Our studies have focused on the synthesis and study of dinuclear Ni complexes supported by redox-active pincer ligands. These complexes catalyze diverse organic transformations, including alkene functionalizations, cycloadditions, and group transfer reactions, through dinuclear mechanisms that involve the coordination of substrates and the distribution of redox activity across multiple metal centers. We discuss the unique catalytic properties that emerge from these cooperativity effects.

Catalysis at metal-metal bonds

251st National Meeting (2016)

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