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

The trisubstituted methyl-phenyl-silyl-cyclopentadienes [Me-Ph-C5H3(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)2SiMe2] have been isolated by conventional methods and characterized by NMR spectroscopy. Desilylation of [Me-Ph-C5H3(SiMe3)] with ZrCl4(SMe2)2 gave the monocyclopentadienyl complex [Zr(η5-1-Ph-3-Me-C5H3)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-C5H2)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-C5H2(SiMe2-η-Nt-Bu)}Cl2] that was further alkylated to give [Zr{η5-2-Me-4-Ph-C5H2(SiMe2-η-Nt-Bu)}R2] (R = Me, CH2Ph) 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.