Propylene polymerization with a bisiminepyridine iron complex: activation with Ph 3C [B(C 6F 5) 4] and AlR 3; iron hydride species in the catalytic cycle

Abstract

In this work, the complex 2,6-bis [1-(2-isopropyl-6-methylphenylimino)ethyl]-pyridineiron(II)dichloride was used for propylene polymerization. Activation with Ph 3C [B(C 6F 5) 4] and subsequent treatment with triisobutylaluminium or triethylaluminium generated a very active polymerization catalyst for propylene. The kinetics of this polymerization reaction were investigated with mass-flowmeters. Further we show propagation-time-profiles of this reaction. Depending on the nature of the aluminiumalkyl we are able to determine different aliphatic endgroups in the polymer using 13 C NMR spectroscopy. Addition of hydrogen to the polymerization leads to higher activities and allows us to formulate a complete catalytic reaction cycle containing an iron hydride species. This cycle comprises one starting cycle and two propagation cycles which can be controlled with the aluminiumtrialkyl-propylene ratio.