tert-Butylsilylcyclopentadienyl Group 4 metal complexes

New Group 4 metal t-butyldimethylsilylcyclopentadienyl complexes [MCpCp′Cl2] (Cp=η5-C5H5; Cp′=η5-C5H4SiMe2tBu; M=Ti 4, Zr 5, Hf 6) were prepared by reaction of 1 equiv. of the lithium (2) and thallium (3) salts of t-butyldimethylsilylcyclopentadiene 1 with the monocyclopentadienyl complexes [MCpCl3·DME] (M=Zr, Hf) and [TiCpCl3], respectively. A similar reaction using ZrCl4(THF)2 and HfCl4 with 2 equiv. of the lithium salt 2 gave the symmetric [MCp′2Cl2] ( M=Zr 7, Hf 8) metallocenes. Alkylation of these compounds with 2 equiv. of MgRCl (R=Me, CH2Ph) and Li(CH2CMe2Ph) afforded the dialkyl complexes [MCpCp′R2] (R=Me, M=Zr 9, Hf 10; R=CH2Ph, M=Ti 11, Zr 12, Hf 13), [ZrCp′2(CH2Ph)2] 14 and [ZrCpCp′(CH2CMe2Ph)2] 17. A Similar reaction of 5 with 1 equiv. of Mg(CH2Ph)Cl gave the monobenzyl compound [ZrCpCp′Cl(CH2Ph)] (15). Hydrolysis of 15 with a stoichiometric amount of water afforded the dinuclear μ-oxo compound [(ZrCpCp′Cl)2(μ-O)] (16). All of the new complexes reported were characterized by elemental analysis and 1H and 13C NMR spectroscopy and the molecular structures of 4 and 16 were determined by X-ray diffraction methods. Ethylene polymerization activities were measured for compounds 4–7.Financial support of our work by MCyT (project MAT2001-1309) is gratefully acknowledged. R.W. and C.R. are grateful to DFG, MEC and Repsol S.A. for fellowships