A unique dimetallic site (Mo(VI)-Cu(I)) in Carbon Monoxide Dehydrogenase (CODH) is capable of oxidizing CO to CO2 while reducing the active site by 2 electrons. Currently, there is no synthetic functional model for the CO oxidation based on the active site of CODH. We have used quantum mechanical calculations to screen models that incorporate functional features similar to the active site. A functional model will most likely possess: a) two redox centers connected by a bridging ligand (most likely sulfido); b) Bulky N, O, or S-containing ligands holding these metal centers at a unique distance, and capable of binding CO; c) a transferable oxygen atom at the Mo-center; d) a proton acceptor for activating H2O during catalysis; and e) an appropriate redox potential for CO oxidation. From our computational screening, we have selected models containing a tris(2-pyridylmethy1)-amine (TPA) and a dimethyl trispyrazoyl borate (TpMe2) ligand on the Mo and Cu centers respectively, which provide strikingly similar structural features of the Mo-S-Cu site in CODH. In addition, TPA is versatile for incorporation of other functional features (like -COOH, -SH) into our synthetic designs. We will report our current findings on the overall synthesis of these model complexes. Synthetic models are valuable for understanding the structure/function relationship in the native enzyme and the overall mechanism of CO conversion.

Developing a novel dimetallic synthetic model complex for carbon monoxide oxidation

251st National Meeting (2016)

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