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 α-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.