New binuclear half-titanocene derivatives with aryl-substituted cyclopentadienyl ligands: synthesis, structures, and catalytic properties

Abstract

Two binuclear oxo-bridged half-titanocene complexes, µ-oxo-bis[(1-aryl-2,3,4,5-tetramethylcyclopentadienyl)dichlorotitanium] [(ArMe4CpTiCl2)2O, Ar = 4- i PrC6H4 (3), 4- t BuC6H4 (4)], have been prepared by the treatment of 1-aryl-2,3,4,5-tetramethylcyclopentadienyltitanium trichloride [ArMe4CpTiCl3, Ar = 4- i PrC6H4 (1), 4- t BuC6H4 (2)] with 0.5 equiv of H2O. Complexes 3 and 4 have been characterized by elemental analysis and 1H- and 13C-NMR (nuclear magnetic resonance; NMR) spectroscopies, and their molecular structures have been determined by X-ray crystallography. When activated with i Bu3Al and Ph3CB(C6F5)4, complexes 3 and 4 both exhibit reasonable catalytic activity for ethylene polymerization (90 × 103 to 280 × 103 kg PE (mol Ti)−1 bar−1 h−1), producing polyethylenes with moderate molecular weight.