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), AlMe<sub>3</sub>, and AlMe<sub>3</sub>/[CPh<sub>3</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] has been studied by <sup>1</sup>H, <sup>2</sup>H, and <sup>19</sup>F 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.