Synthesis, characterization and polymerization properties of bridged halfsandwich complexes of titanium, Zirconium and Hafnium - The molecular structure of [C13H8-SiMe2-(NBu)-Bu-t]ZrCl2

The synthesis of new ansa halfsandwich complexes of the type [Cp-not equal -SiMe2-N'Bu]MCl2 (Cp-not equal = C13H8, C9H6, C5H4, C5H3'Bu; M = Zr, Hf) as catalyst precursors for the polymerization of ethylene is described. The c omplexes were characterized by H-1-, C-13-, Si-29-, N-15- and N-14-NMR spec troscopy. From [C13H8-SiMe2-N'Bu]ZrCl2 an X-ray structure was obtained. The activities of the catalysts and the properties of the polymers were invest igated. The influence of the catalyst structure on the polymerization behav iour is discussed.