Titanium complexes stabilized by a sulfur-bridged chelating bis(aryloxo) ligand as active catalysts for olefin polymerization

Abstract

The mixed-ligand complexes [Ti2(μ-OR)2(OR) 2(κ3-tbop)2] (1a) for R = Me and (1b) R = Et were prepared by the reaction of Ti(OR)4 and H2tbop [H2tbop = 2,2′-thiobis[4-(1,1,3,3-tetramethylbutyl)phenol]} in methanol. Treatment of 1a and 1b with AlMe3 led to the substitution of terminal alkoxy groups to create the organometallic compounds [Ti 2(μ-OR)2(κ3-tbop)2(Me) 2] (2a) for R = Me and (2b) for R = Et. Controlled hydrolysis of 2b causes the evolution of methane and the formation of the titanoxane compounds [{Ti2(μ-OEt)2(κ3-tbop) 2}2(μ-O)2]·2CH2Cl 2 (3). Structures of 1a, 1b, 2a, 2b, and 3 were confirmed by NMR spectroscopy; 1b and 3 were further investigated with X-ray crystallography. Compounds 1a, 1b, 2a, and 2b were supported on MgCl2 and when activated with aluminum alkyls, found to effectively polymerize ethylene. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.