Nickel model complexes to mimic carbon monoxide dehydrogenase reactions

Biological CO₂/CO interconversion catalyzed at the Ni/Fe heterobimetallic active site of anaerobic carbon monoxide dehydrogenases (CODHs) offers important insights for the design of efficient and selective synthetic catalysts for CO₂ capture and utilization (CCU). Notably, this organometallic C₁ interconversion process is mediated at a three-coordinate nickel site. Extensive research has been conducted to elucidate the redox and structural changes involved in substrate binding and conversion. The CO₂-bound structure of CODH, in particular, has inspired many synthetic studies aimed at exploring key questions, concerning the choice of metal, the role of the unique iron (Fe_u), and the geometry and oxidation states of both Ni and Fe_u, as well as CO₂/CO exchange mechanism. A better understanding of CODH chemistry promises to reveal and uncover fundamental principles for small molecule activation of first-row transition metal complexes. This mini-review focuses on three key aspects: (1) the coordination environment of the Ni centre in CODH, (2) bioinorganic Ni model systems that provide insight into the biological CO₂/CO interconversion at the CODH active site, and (3) recent advances in CODH-inspired catalysis for selective CO₂-to-CO conversion.