Oxovanadium(V) catalysts for the CO2 fixation into cyclic carbonates under ambient pressure

Developing feasible strategies to utilize CO2 as a C-1 synthon for constructing various valued-added chemical feedstock is crucial for alleviating the global warning and achieving a carbon-neutral cycle. The coupling between epoxide and carbon dioxide is a promising direction due to the large driving force for the formation of thermodynamically stable cyclic carbonate and its 100% atom-economy efficiency. Despite numerous metal-based complexes that have been reported to facilitate this coupling reaction catalytically, harsh conditions (high temperature and pressure) are usually required. In this study, the synthesis and structural/spectroscopic characterizations of oxovanadium(V) complexes 2a-2f chelated with one-step synthesized hydrazone-imidate ligands were reported. The catalytic performance of the synthesized oxovanadium(V) complexes regarding the coupling reaction between epoxide and CO2 was successfully demonstrated with only 0.5 mol% loading of both oxovanadium(V) catalyst and [NBu4][Br] at 80 degrees C under 1 bar of CO2. The substrate scope containing both terminal epoxide derivative and internal epoxide derivative indicates that the oxovanadium(V) catalysts could exert efficient catalytic coupling reaction of terminal epoxide (63 similar to 85% conversion rates) under ambient pressure of CO2.