Investigating the Nature of the Active Species in Bis(imino)pyridine Cobalt Ethylene Polymerization Catalysts

The activation of bis(imino)pyridine cobalt-based catalysts of ethylene polymerization with methylalumoxane (MAO), AlMe3, and AlMe3/[CPh3][B(C6F5)4] has been studied by 1H, 2H, and 19F NMR and EPR spectroscopy. The nature of the active sites of polymerization is discussed. The polymerization kinetics and the polymer properties for the different catalyst/activator systems were correlated with spectroscopic data.