Synthesis, crystal structure and ethylene polymerization activity of zirconium complexes bearing mono-Cp and tridentate Schiff base [ONO] ligands

A novel zirconium complex 1 bearing mono-Cp and tridentate Schiff base [ONO] ligand is synthesized by the reaction of CpZrCl3 · DME with lithium salt of Schiff base ligand. The molecular structure of complex 1 is determined by X-ray single crystal diffraction. A nine-membered zirconoxacycle complex 2 is obtained by an intramolecular elimination of CH3Cl from complex 1. When activated by excess methylaluminoxane (Al/Zr = 2000:1), complexes 1 and 2 exhibit high thermal stability and high catalytic activities for ethylene polymerization [1, 769 kg PE/(mol Zr · h); 2, 272 kg PE/(mol Zr · h) at 80 °C].