Olefin polymerization with Me4Cp-amido complexes with electron-withdrawinggroups

A series of Me,Cp-amido complexes {[eta (5):eta (1)-(Me4C5)SiMe2NR]TiCl2; R = t-Bu, 1; C6H5, 2; C6F5, 3; SO2Ph, 4; or SO2Me, 5} were prepared and inve stigated for olefin polymerization in the presence of methylaluminoxane (MA O). X-ray crystallography of complexes 3 and 4 revealed very long Ti-N bond s relative to the bonds of 1. These complexes were employed, for ethylene-s tyrene copolymerizations, styrene homopolymerizations, and propylene homopo lymerizations in the presence of MAO. The productivities of the catalysts d erived from 3-5 were much lower than the productivity of the catalyst deriv ed from 1 for the propylene polymerizations and ethylene-styrene copolymeri zations, whereas the styrene polymerization activities were much higher for the catalysts derived from 3-5 than for the catalyst derived from 1. The p olymerization behavior of the catalysts derived from the metallocenes 3-5 w ere more reminiscent of monocyclopentadienyl titanocene Cp'TiX3/MAO catalys ts than of CpATiX(2)/MAO catalysts such as 1 containing alkylamido ligands. (C) 2000 John Wiley & Sons, Inc.