Synthesis and characterization of methyl-phenyl-substituted cyclopentadienyl zirconium complexes

Article abstract of DOI:10.1016/j.jorganchem.2004.10.044

The trisubstituted methyl-phenyl-silyl-cyclopentadienes [Me-Ph-C ₅H₃(SiMe₂X)] (X = Me, Cl, NHt-Bu) and [(Me-Ph-C₅H₃)₂SiMe₂] and the lithium salts Li₂[Me-Ph-C₅H₂(SiMe₂Nt-Bu)] and Li₂[(Me-Ph-C₅H₂)₂SiMe ₂] have been isolated by conventional methods and characterized by NMR spectroscopy. Desilylation of [Me-Ph-C₅H₃(SiMe ₃)] with ZrCl₄(SMe₂)₂ gave the monocyclopentadienyl complex [Zr(η⁵-1-Ph-3-Me-C₅H ₃)Cl₃]. The ansa-metallocene [Zr{(η⁵-2-Me- 4-Ph-C₅H₂)SiMe₂(η⁵-2-Ph-4-Me- C₅H₂)}Cl₂] was obtained from the mixture of isomers formed by transmetallation of Li₂[(Me-Ph-C₅H ₂)₂SiMe₂] to ZrCl₄ and characterized as the meso-diastereomer by X-ray diffraction methods. Similar transmetallation of Li₂[Me-Ph-C₅H₂(SiMe₂Nt-Bu)] gave the silyl-η-amido complex [Zr{η⁵-2-Me-4-Ph-C ₅H₂(SiMe₂-η-Nt-Bu)}Cl₂] that was further alkylated to give [Zr{η⁵-2-Me-4-Ph-C₅H ₂(SiMe₂-η-Nt-Bu)}R₂] (R = Me, CH ₂Ph) and used as a catalyst precursor, activated with MAO, for ethene and propene polymerization. All of the new compounds were characterized by elemental analysis and NMR spectroscopy.