Stereospecific metallocene catalysts: Scope and limits of rational catalyst design

Structure-performance relationships in the propene polymerization behaviour of a number of silicon bridged bisindenyl zirconocenes show a rational pattern. Prognosis of the polymerization behaviour of different type structures, however, often fails, which is demonstrated by three examples of new zirconocenes. These include two bisindenyl complexes with two-membered silicon bridges and one isospecific bridged fluorenyl cyclopentadienyl species. It is thus demonstrated that the scope of a “rational catalyst design” in the field of metallocene catalysts is still limited.