Quinoline-8-olato-chromium catalysts with pseudohalogen effects for the CO2/cyclohexene epoxide copolymerization

[Display omitted] Based on our previous studies utilizing CrIII catalysts with trifluoroacetate as labile ligand and an ansa-bis-quinoline-olato ligand as a chemically more robust variant compared to known salen-type N2O2 ligands, we synthesized and investigated a series of structurally similar quinoline-8-olato chromium complexes with different active (pseudo-)halogen ligands X in [(babhq)CrX], (babhq = 2,2′-(butyl-azanediyl)bis(quinolin-8-olate), X = Cl, NCO, and N3. We demonstrate a high activity of these CrIII complexes in the solvent free carbon dioxide/cyclohexene oxide (CHO) copolymerization compared to the state of the art. In much deeper detail than in our previous communication, we altered the labile ligand X and undertook a catalyst screening on the polymerization parameters, such as pressure, temperature, and cocatalyst, i.e. [PPN]N3 (bis(triphenylphosphine)iminiun azide). The activity of the chromium systems was found to much depend on the labile (pseudo-)halogen ligand X and increases in the order Cl