Multiple metal centers are used both in metallocofactors and in surfaces to drive difficult reaction chemistry. The synergistic efforts of multiple metals towards small molecule activation lowers the barrier towards molecular breakdown. Previous efforts in the Betley group have resulted in generation of trinuclear complexes using a hexadentate ligand and various first row transition metals. Herein, we report reactivity of carbon monoxide with trinuclear complexes. Initial carbon monoxide addition is driven by metal identity. Addition of carbon monoxide to homotrinuclear divalent cobalt complexes (d7) occurs once at each metal center, resulting in a local square planar geometry, while addition of carbon monoxide to homotrinuclear divalent iron complexes (d6) occurs three times at a single metal center, resulting in a local octahedral geometry. The kinetics of carbon monoxide addition to trinuclear complexes is sensitive to exogenous ligand, allowing trapping of single carbon monoxide adducts. Reduction of the tricobalt carbon monoxide adduct results in a change in carbon monoxide bonding from being �1 to a single metal center to �3 to all three metal centers, and a corresponding substantial increase in the degree of activation. Reaction of the reduced bridging carbon monoxide adduct with electrophiles results in loss of carbon oxygen multiple bond character, as determined by IR spectroscopy.

Carbon monoxide activation and reactivity driven by open shell trinuclear complexes

248th National Meeting (2014)

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