Novel octahydro- and tetrahydro-fluorenyl containing C1 symmetric zirconocenes for the stereoregular polymerization of propylene

The synthesis and polymerization behavior of two new asymmetric metallocenes containing partially or fully hydrogenated fluorenyl moieties is reported. The zirconocenes, dimethylsilylene-[η5-1-(2-methyl-4-phenyl)indenyl]-(η5-9-tetrahydrofluorenyl) zirconium dichloride (9) and dimethylsilylene-[η5-1-(2-methyl-4-phenyl)indenyl]-(η5-9-octahydrofluorenyl) zirconium dichloride (10) were both found to be very stable complexes that were highly active catalyst precursors for the polymerization of ethylene and propylene. In the case of propylene, activities approaching 108 g polymer ([mol Zr] [monomer] h)−1 were obtained. Highly stereoregular polypropylene was produced at room temperature. The complexes 9 and 10 were significantly more stable and more active than the previously prepared fluorenyl analog.