Reactivity of a Ruthenium(0) Complex Bearing a Tetradentate Phosphine Ligand: Applications to Catalytic Acrylate Salt Synthesis from Ethylene and CO2

By using a zerovalent, electron-rich ruthenium complex bearing a tetradentate phosphine ligand, a five-membered ruthenalactone was generated by oxidative cyclization of ethylene and CO2. This ruthenalactone underwent thermal, reversible β-H elimination to afford an acrylato(hydrido)ruthenium(II) complex, which liberated acrylate salt on treatment with a base. The reaction was successfully applied to the first ruthenium-catalyzed synthesis of an acrylate salt from ethylene and CO2. This study demonstrated the feasibility of the electron-rich ruthenium(0) complex as a catalyst in CO2-fixation chemistry.