Polymerization Catalyses of Chromium Complexes Having N-donor Ligands

摘要

A series of chromium(III)complexes having chelating N-donor ligand such as bis(imino)pyridine derivatives was synthesized,and polymerization catalyses of these complexes were investigated.Upon activation with MAO(methylalumioxane),these complexes showed low activities for polymerization of ethylene.On the other hand,combination of these complexes with MMAO(modified-methylaluminoxane)showed high activities for the polymerization of ethylene.The substituents at the ortho position of N-aryl groups of the bis(imino)pyridine ligands affected both the catalytic activity and the molecular weights of the resulting polyethylene.Two small substituents led to highly active systems,although the molecular weight of the resulting polyethylene was rather low.The two small substituents system also achieved high incorporation of 1-hexene in copolymerization of ethylene and 1-hexene.