Group 4 metallocene complexes with non-bridged and tetramethyldisiloxane-bridged methyl-phenyl-cyclopentadienyl ligands: synthesis, characterization and olefin polymerization studies

Abstract

The non-vicinal methyl-phenyl-substituted zirconocene dichlorides meso-and rac-[Zr{η5-(1-Ph-3-Me-C5H3)}2Cl2] and [Zr(η5-C5H5){η5-(1-Ph-3-Me-C5H3)}Cl2] have been isolated by transmetallation of the lithium salt Li(1-Ph-3-Me-C5H3) to ZrCl4(THF)2 and [Zr(η5-C5H5)Cl3 · DME] (DME = dimethoxyethane), respectively. Similar transmetallation of the lithium salt Li2[(Me-Ph-C5H2SiMe2)2O] to MCl4 gave the ansa-metallocenes [M{η5-(Me-Ph-C5H2SiMe2)2O}Cl2] (M = Zr, Hf) for which the meso- and rac-diastereomers were separated. The dimethyl and dibenzyl derivatives of these metallocenes were also prepared and the structure of all of these compounds determined by NMR spectroscopy. The molecular structure of rac-[Zr{η5-(2-Me-4-Ph-C5H2SiMe2)2O}Cl2] was determined by single crystal X-ray diffraction methods. The activity of the dichlorometallocenes/MAO catalysts for ethene and propene polymerization was evaluated.