13C NMR Analysis of α-Olefin Enchainment in Poly(α-olefins) Produced with Nickel and Palladium α-Diimine Catalysts
journal contributionposted on 06.02.2007, 00:00 by Elizabeth F. McCord, Stephan J. McLain, Lissa T. J. Nelson, Steven D. Ittel, Daniel Tempel, Christopher M. Killian, Lynda K. Johnson, Maurice Brookhart
α-Diimine complexes of palladium and nickel catalyze the polymerization of α-olefins to give new materials that range from low-Tg elastomers to low-melting, partially crystalline polymers. The 1H and 13C NMR spectra of the resulting polymers have been assigned in detail. Many unique microstructural features of the complex polymers have been identified. Mechanistic models that involve the 1,2- and 2,1-insertion of the α-olefins, chain walking, and insertion at certain points along the chain have been constructed. The complex microstructures can be explained using a small set of rules for palladium catalysts which is expanded slightly to account for the nickel catalysts.