[ONSN]-type chromium complexes catalyzed coupling of CO2 with epoxides

A new family of [ONSN]-type chromium complexes bearing hybrid coordination site (O, N, S) have been developed for the coupling of epoxides with CO 2 . The catalytic system resulting from the complex C2 in combination with TBAB shows the high activity for the cycloaddition of epoxides with CO 2 with a broad range of substrates including terminal epoxides and internal epoxides. When catalytic system is switched from complex C2 and TBAB to complex C3 and PPNCl as well as regulation of the reaction conditions, which causes the variation of chemo-selectivity and allows the highly selective synthesis of poly(cyclohexene carbonate) by employing cyclohexene oxide as substrate. The spectroscopic analysis, including UV–vis, FT-IR, and ESIMS, pointed to the formation of new chromium complex, which may be an active species in the reaction. • Four [ONSN]-type chromium complexes were synthesized and showed high performance for coupling of CO 2 with epoxides. • The catalytic system allowed chemo-selective synthesis of cyclohexene carbonate or poly(cyclohexene carbonate). • The chromium complexes catalyzed mechanism was elucidated by UV–vis, FT-IR, and ESIMS spectroscopy.