Zirconium Complexes Having Phenoxy/Cycloalkylimine Chelate Ligands:Crystal Structures and Ethylene Polymerization Behavior

摘要

Zirconium complexes having two phenoxy-imine chelate ligands in which the imine-nitrogen possesses a cycloalkyl group have been prepared.Upon activation with MAO,these complexes are highly active catalysts for ethylene polymerization and generate polyethylenes having low(M_w 1900)to high(M_w 471000)molecular weights with high efficiency.The influence of substituents of the ligands on molecular weights can be explained by steric congestion around polymerization center,as suggested by X-ray crystallographic analysis.