Isoselective Living Polymerization of 1-Hexene Catalyzed by Half-Metallocene Dimethyl Complexes of Hafnium with Bidentate N-Substituted (Iminomethyl)pyrrolyl Ligands

The nonbridged half-metallocene dimethylhafnium complexes 3a−c with N-substituted (iminomethyl)pyrrolyl ligands 2a−c have been synthesized and characterized by NMR spectroscopy as well as X-ray analyses for 3a,b. These complexes were found to be active catalysts for the isoselective living polymerization of 1-hexene upon treatment with [Ph3C][B(C6F5)4] below 0 °C.