Strategies for Tuning the Catalytic Activity of Zinc Complexes in the Solvent-Free Coupling Reaction of CO2 and Cyclohexene Oxide

• In the coupling reaction of CO 2 and cyclohexene oxide, the catalytic activity of zinc complexes can be easily tuned. • Triflate ancillary ligands can turn on the catalytic activity of zinc complexes bearing a chelating nitrogen donor ligand. • Zinc complexes bearing triflates can be good catalysts for the ring-expansive carboxylation of cyclohexene oxide with CO 2 . The catalytic activity of various zinc(II) complexes bearing a chelating nitrogen-donor ligand and different ancillary ligands (Cl, acetate, triflate) is investigated for the solvent-free coupling reaction of cyclohexene oxide and CO 2 . The effect of a co-catalyst is also studied. Whereas the investigated zinc(II) complexes with chloride or acetate as ancillary ligand are inactive, those with triflate are active, allowing the selective formation of polyether or cyclic carbonate controlled by the presence of a suitable amount of [PPN]Cl.