A New Zirconocene Complex and Its Catalytic Properties for Olefin Polymerization

As metallocene olefin polymerization catalysts, unbridged metallocene complexes have recevied much attention because they are relatively easy to be synthesized and can produce not only polyethylene but also oligo- or polypropylenes with different stereoregularities and properties depending on their structures[1,2]. It has been known that a rather small structural change for a metallocene compound may cause a remarkable effect on its catalytic properties, such as catalytic activity, polymer molecule weight and microstructure[3]. In this respect, we have recently focused our research interest on the ligand modification of unbridged metallocene complexes and their catalytic behavior. The present paper covers the synthesis and characterization of a new zirconocene complex, bis(1-methyl-3,4-diphenylcyclopentadienyl)zirconium dichloride(1), and its unusual catalytic properties for ethylene and propylene polymerizations. To our knowledge, this compound is the first example of metallocene complexes with 1-alkyl-3,4-diarylcyclopentadienyl as the ligand.