Model complexes for nickel containing enzymes: Carbon monoxide dehydrogenase/ acetyl coenzyme a synthase and nickel superoxide dismutase
Carbon Monoxide Dehydrogenase / Acetyl CoA Synthase (CODH/ACS) is a bifunctional enzyme that catalyzes the reduction of CO₂ to CO and the assembly of Acetyl CoA. The A-cluster active site, which catalyzes the Acetyl CoA synthesis, contains a Fe-S cubane bridged by a cysteine thiolate to a dinuclear Ni(µ-S)₂Ni cluster (Fig. 1). The proximal nickel, Nip, has S₃X coordination, while the distal nickel, Nid, has N₂S₂ coordination. This project focuses on the synthesis of model complexes for the asymmetric dinuclear metal center in order to understand the electronic characteristics of this cluster and investigate the feasibility of proposed intermediates. The initial target compound is shown in Figure 2. We have developed an efficient method for synthesizing metal complexes with mixed N/S coordination through the use of 2-2'-dithiodibenzaldehyde, DTDB. Symmetric nickel complexes with NS₃ coordination have previously been synthesized using DTDB and various bidentate NS ligands. Herein we present our results upon incorporating N,N-dimethylethylenediamine into this methodology.
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