Accessing Multiple Catalytically Active States in Redox-Controlled Olefin Polymerization

The majority of work in the field of olefin polymerization catalysis has been focused on ligand modifications. In this work, we describe an alternative strategy for the modulation of olefin polymerization and copolymerization processes. The two ferrocenyl units in an a-diimine palladium catalyst can be oxidized in a stepwise fashion. This stepwise redox control can be used to modulate the catalyst properties during the homopolymerization of ethylene and 1-hexene, as well as the copolymerizations of ethylene with norbornene, methyl acrylate, and 5-norbornene-2-yl acetate. Moreover, polymer microstructure and polydispersity can be controlled during these stepwise oxidation processes.