G. Jany et al., PARA-FLUORO BENZYL SUBSTITUTED BIS(INDENYL) METALLOCENES AS CATALYST PRECURSORS IN ETHENE POLYMERIZATION, Journal of organometallic chemistry, 553(1-2), 1998, pp. 173-178
The unbridged complexes bis(eta(5)-(1-para-fluoro benzyl)indenyl) MCl2
(2: M = Hf; 3: M = Zr) as well as their ethylene bridged analogues bi
s[(eta(5)-3-(1-para-fluoro benzyl)indenyl)ethane] MCl2 (4: M = Hf; 5:
M = Zr) have been synthesized and the obtained rac- and meso-isomers w
ere separated from the 1:1 isomer mixtures. Complexation was performed
by converting the ligand precursors (1-para-fluoro benzyl)indene (1a)
and bis(3-(1-para-fluoro benzyl)indenyl)ethane (1b) into their lithio
salts and further treatment with MCl4. To study the influence of the
para-fluoro benzyl substituent in ethene polymerization, the catalyst
precursors 2-5 were activated with methylalumoxane (MAO) and their pol
ymerization behavior was compared to corresponding unsubstituted metal
locenes. The crystal structure of meso-like 3 was determined by means
of X-ray structure analysis, showing a central/lateral: gauche-type or
ientation of its para-fluoro benzyl substituents in the solid state. (
C) 1998 Elsevier Science S.A.