Olefin polymerization with Me 4 Cp–Amido complexes with electron‐withdrawing groups

Abstract

A series of Me 4 Cp-amido complexes ([η 5 ;η 1 -(Me 4 C 5 )SiMe 2 NR)TiCl 2 ; R = t-Bu, 1; C 6 H 5 , 2; C 6 F 5 , 3; SO 2 Ph, 4; or SO 2 Me, 5) were prepared and investigated for olefin polymerization in the presence of methylaluminoxane (MAO). X-ray crystallography of complexes 3 and 4 revealed very long Ti-N bonds relative to the bonds of 1. These complexes were employed for ethylene-styrene copolymerizations, styrene homopolymerizations, and propylene homopolymerizations in the presence of MAO. The productivities of the catalysts derived from 3-5 were much lower than the productivity of the catalyst derived from 1 for the propylene polymerizations and ethylene-styrene copolymerizations, whereas the styrene polymerization activities were much higher for the catalysts derived from 3-5 than for the catalyst derived from 1. The polymerization behavior of the catalysts derived from the metallocenes 3-5 were more reminiscent of monocyclopentadienyl titanocene Cp'TiX 3 /MAO catalysts than of CpATiX 2 /MAO catalysts such as 1 containing alkylamido ligands.