O-Phenylene-bridged Cp/amido titanium and zirconium complexes and their polymerization reactivity

Abstract

o-Phenylene-bridged trimethylcyclopentadienyl/amido titanium complexes [(η 5-2,3,5-Me 3C 5H)C 6H 4NR-κ N]TiCl 2 ( 18, R = CH 3; 19, R = CH 2CH 3; 20, R = CH 2C(CH 3) 3; 21, R = CH 2(C 6H 11)) and zirconium complexes {[(η 5-2,3,5-Me 3C 5H)C 6H 4NR-κ N]ZrCl-μCl} 2 ( 22, R = CH 3; 23, R = CH 2CH 3; 24, R = CH 2C(CH 3) 3; 25, R = CH 2(C 6H 11); 26, R = C 6H 11; 27, R = CH(CH 2CH 3) 2) are prepared via a key step of the Suzuki-coupling reaction between 2-dihydroxyboryl-3-methyl-2-cyclopenten-1-one ( 2) and the corresponding bromoaniline compounds. The molecular structures of titanium complexes 18 and 19 and dinuclear zirconium complexes 24 and 26 were confirmed by X-ray crystallography. The Cp(centroid)–Ti–N and Cp(centroid)–Zr–N angles are smaller, respectively, than those observed for the Me 2Si-bridged complex [Me 2Si(η 5-Me 4C 5)(N t Bu)]TiCl 2 and its Zr-analogue, indicating that the o-phenylene-bridged complexes are more constrained than the Me 2Si-bridged complex. Titanium complex 19 exhibits comparable activity and comonomer incorporation to the CGC ([Me 2Si(η 5-Me 4C 5)(N t Bu)]TiCl 2) in ethylene/1-octene copolymerization. Complex 19 produces a higher molecular-weight polymer than CGC.