Synthesis, structures and polymerization catalytic properties of germyl-bridged bis(cyclopentadienyl) metallocenes

The ansa-metallocene complexes Me2Ge(eta(5)-C5Me4)(2)MCl2 [M = Ti (1), Zr (2)], Me2Ge(eta(5)-C5H3Bu-t)(2)ZrCl2 (3) and Me2Ge(eta(5)-C5H4)(eta(5)-C5H3R)ZrCl2 [R = Me (4), t-Bu (5)] were prepared by the reaction of the corresponding ligands with n-BuLi and MCl4.2THF, respectively. The molecular structures of 1 and 2 have been determined by the X-ray diffraction method. Complexes 2-5 in combination with MAO were studied as catalysts for ethylene polymerization and all the germyl-bridged zirconocene catalysts show high activities at relative high temperatures. This indicates that the germyl-bridged zirconocene systems show thermally stable catalyst systems for polymerization of ethylene. (C) 2002 Elsevier Science B.V. All rights reserved.