Development of a Clean Carbon Recycleing System from Environmentally Hazardous Substances with the Key to the Formation and Cleavage of Cobalt-Carbon Bonds

The bioinspired catalyst system was developed in the interdisciplinary fields of bioinorganic chemistry and catalytic chemistry. In nature, enzymes catalyze various molecular transformations under mild conditions with a high efficiency and selectivity. Therefore, we can learn about many excellent systems from nature. As for the catalyst design, a metal complex inspired by the active site of a metal enzyme has been developed and the combination of the metal complex with a redox system should form an excellent catalytic system. Based on this concept, we can use various redox systems such as electrochemistry and photoexcited chemistry to construct a catalyst system. Among the metal complexes inspired from natural metal enzymes, the cobalt ion containing the B₁₂ derivative is the focus on this account. Organometallic B₁₂ complexes are unique metal complexes having a cobaltcarbon σ bond that exist in biological systems. Cleavage of the metalorganic σ bond initiates many B₁₂ dependent enzymatic reactions. Based on the unique properties of alkylated cobalt complex, many B₁₂inspired reactions have been developed. Here the visible light driven B₁₂ inspired reaction for the synthesis of various compounds from organic halides as carbon source were summarized, and the combination of the B₁₂ derivative as redox catalyst in electroorganic synthesis for the conversion of various trichloromethylated organic compounds to amides was reviewed.