Polymerization of propylene by zirconocenium catalysts with different counter‐ions

Propylene was polymerized by binary zirconocenium catalysts derived from rac‐ethylenebis(1‐η5‐indenyl)dimethylzirconium and cation forming agents (C6H5)3C+(C6F5)4B− and (C6F5)3B. Polymerizations were also performed with the ternary systems of Et[Ind]2ZrCl2, Et3Al, and the cation forming agents. The catalyst systems, with the inert noncoordinating counter‐ion, (C6F5)4B−, have much higher activity and stereoselectivity than the ones with the CH3B−(C6F5)3 counter‐ion. Much less active still are catalysts having BF4− or (C6H5)4B− counter‐ions. Similar but smaller effects of counter‐ion structure on ethylene polymerization were observed.