Synthesis, crystal structure and catalytic activity of some new chiral ansa-metallocenes of yttrium, lanthanum, samarium, lutetium and of zirconium

Chiral silicon bridged yttrio- and lanthanidocene chlorides [MeRSi(C2H4)(C5 Me4)LnCl](2) (R = Et (a), Ph (b); Ln = Y (4a, b), La (5a, b), Sm (6a. b), L u (7a, b)) and zirconocene dichlorides [MeRSi(C5H4)(C5Me4)ZrCl2] (R = Er (8 a), Ph (8b)) were synthesized. Compounds 4-7 react with sodium acetate yiel ding the corresponding monomeric acetates [MeRSi(C5H4)(C5Me4)LnO(2)CMe] (R = Et (a), Ph (b); Ln = Y (9a, b), La (10a, b), Sm (11a, b), Lu (12a, b)). A ll compounds were characterized by elemental analysis, H-1 and C-13{H-1}-NM R spectroscopy, and by mass spectrometry. Single crystal X-ray structure de terminations show a dimer for 6a and a monomer for 8a. The zirconocenes 8a, b art: active catalysts for the polymerization of ethylene and propylene i n the presence of methylalumoxane (MAO). (C) 1999 Elsevier Science S.A. All rights reserved.