Metallacyclic metallocene complexes as catalysts for olefin polymerization

Metallacyclic metallocene complexes of titanium, zirconium and hafnium can be prepared by hydrogen elimination processes of suitable substituents such as ω-phenylalkyl or ω-alkenyl at the aromatic ligands. In some cases, the intermediates containing agostic hydride ligands can be isolated and characterized. The synthesized metallacyclic metallocene complexes can be activated with methyl aluminoxane (MAO) and are then able to polymerize 1-olefins catalytically. The advantages of such catalysts are their high thermal stability and their potential of self-immobilization combining the advantages of homogeneous and heterogeneous catalysis and their high activities. In some cases these catalysts show activities that are three to four times higher than the activities of the parent dichloride complexes. The fact that these catalysts do not contain any halides and that they remain in the produced polymer makes them very friendly to the environment when they are thermally decomposed.