Synthesis and characterization of titanium alkyl, oxo, and diene complexes bearing a SiMe2-bridged phenoxy-cyclopentadienyl ligand and their catalytic performance for copolymerization of ethylene and 1-hexene

Abstract A series of titanium complexes bearing a SiMe 2 -bridged phenoxy-cyclopentadienyl ligand were synthesized and characterized, and their catalytic behavior for copolymerization of ethylene and 1-hexene was investigated. Treatment of dimethylsilyl(2,3,4,5-tetramethylcyclopentadienyl)(3- tert -butyl-5-methyl-2-phenoxy)-titanium dichloride ( 1 ) with appropriate nucleophiles afforded dimethoxy complex 2 , dimethyl complex 3 , and dibenzyl complex 4 . Standing a toluene solution of 2 in air afforded a dinuclear μ-oxo complex 5 as a single isomer. 1,3-Diene complexes 6 – 8 were prepared by reaction of 1 with the corresponding 1,3-dienes in the presence of 2 equiv. of n -BuLi. X-ray analysis of 1,4-diphenyl-1,3-butadiene complex 6 revealed that the diene ligand coordinates to titanium in s - cis fashion with a prone orientation. The newly prepared titanium complexes were applied to copolymerization of ethylene and 1-hexene upon activation with Al i Bu 3 and [C 6 H 5 NMe 2 H][B(C 6 F 5 ) 4 ]. It was found that the alkyl complexes 3 – 4 and the diene complexes 6 – 8 showed higher activities than 1 at elevated temperature.