Cocatalyst effect in propylene polymerization reactions with post-metallocene catalysts

Effect of cocatalysts on the performance of three post-metallocene catalysts based on complexes I–III in is studied by comparing their activity in the presence of two cocatalysts, MAO and a combination of AlEt2Cl and MgBu2, in propylene polymerization reactions. The second cocatalyst produces significantly more active catalysts. Analysis of GPC, DSC and 13C NMR data for the polymers suggests that the activity increase is caused by the formation of new types of active centers. Some of the new centers are isospecific and operate according to the enantiomorphic stereocontrol mechanism.