Triazole based cobalt catalyst for CO₂ insertion into epoxide at ambient pressure

Over the past decades, a lot of efforts have been made for the fixation of carbon dioxide (CO₂) into epoxide for the synthesis of industrially important cyclic carbonates. Here, a cobalt(II) complex based on triazole, namely Co(II)-1,2,3-1H-triazole-4-carboxylate, was synthesized, fully characterized by FTIR, NMR, mass spectrometry, and single crystal X-ray diffraction, and used as a catalyst for the cycloaddition of CO₂ to epoxides. The catalytic studies demonstrated that the catalyst is highly active for the CO₂ fixation, with high turnover number (TON, 85 × 10³) even without the use of solvent and at ambient pressure (1 bar) to produce a variety of different cyclic carbonates depending on the epoxide. Remarkably, the catalyst was used continuously further by the addition of a fresh amount of the substrate within the same reaction mixture for at least five successive reaction cycles without any loss in the catalytic activity.