Active Intermediates in Ethylene Polymerization over Titanium Bis(phenoxyimine) Catalysts

Reactive intermediates in living olefin polymerization over homogeneous catalysts based on bis[N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato]titanium(IV) dichloride (L2TiCl2) have been studied. Outer sphere ion pairs [L2TiMe(S)]+[Me-MAO]- and [L2TiMe(S)]+[B(C6F5)4]- (S = solvent molecule), formed by activation of L2TiCl2 with MAO or with AlMe3/[CPh3]+[B(C6F5)4]-, and reactions of these ion pairs with ethene to afford chain-propagating species [L2TiP]+[Me-MAO]- and [L2TiP]+[B(C6F5)4]- (P = growing polymeryl chain) have been characterized by 1H, 13C, and 19F NMR spectroscopy.