Polymerization of Propylene by Nonbridged Zirconocene Complexes.

Nonbridged zirconocene dichlorides, (1,2-Me-2-4-RC5H2)(2) ZrCl2 (R = Me (3), Ph (4), p-FC6H4 (5), 2-furyl (6), 2-thienyl (7), and Fc (8)), and meso- and rac-(1-Me-3-PhC5H3)(2)ZrCl2 (9 and 10), in the presence of MAO show a high catalytic activity (8.1 similar to 17.4 x 10(6) gPP/molZr.h) in the polymerization of propylene and produce almost an atactic elastomeric polymer of high molecular weight (Mw = 10.5 similar to 23.2 x 10(4)). In contrast, rac-(1-Me-3-t-BuC5H3)(2)ZrCl2 (12) shows very low activity and produces a rather high isotactic polymer of low molecular weight.