2-Aldiminophenoxytitanium chloride complexes: Synthesis, characterization, and ethylene (co-)polymerization behavior

A series of trichlorotitanium 2-aldiminophenoxylate complexes (C1-C6) was synthesized by the stoichiometric reaction of TiCl 4(THF) 2 with the potassium salts of 6-alkyl-2-aldiminophenolates derived from ligands (L1-L6) bearing a bulky benzhydryl substituent, whereas the bis(2- aldiminophenoxy)titanium dichloride (C7) was isolated in the reaction of a ligand L6 with 0.5 equivalents of TiCl 4(THF) 2. All titanium complexes were characterized by 1H/ 13C NMR spectroscopy and elemental analysis. Single-crystal X-ray diffraction revealed distorted octahedron geometries around the titanium center for complexes C2, C4 and C7. Upon activation with the co-catalyst MAO, all titanium pre-catalysts exhibited good to high activities (up to 1.3 × 10 6 g mol (Ti) -1 h -1) for ethylene polymerization at 70 °C, producing polyethylene products with high molecular weights. Furthermore, co-polymerization of ethylene with either α-olefins or norbornene was achieved with activities in the range of 10 5 g mol (Ti) -1 h -1 by these titanium pre-catalysts along with good incorporation of co-monomer, typically 4.5 mol % for 1-hexene or 13.5 mol % for norbornene, respectively. © 2012 Elsevier B.V. All rights reserved