Tert-Butylsilylcyclopentadienyl Group 4 metal complexes

Abstract

New Group 4 metal t-butyldimethylsilylcyclopentadienyl complexes [MCpCp′Cl 2] (Cp=η 5-C 5H 5; Cp′=η 5-C 5H 4SiMe 2 t Bu; 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 [MCpCl 3·DME] (M=Zr, Hf) and [TiCpCl 3], respectively. A similar reaction using ZrCl 4(THF) 2 and HfCl 4 with 2 equiv. of the lithium salt 2 gave the symmetric [MCp′ 2Cl 2] ( M=Zr 7, Hf 8) metallocenes. Alkylation of these compounds with 2 equiv. of MgRCl (R=Me, CH 2Ph) and Li(CH 2CMe 2Ph) afforded the dialkyl complexes [MCpCp′R 2] (R=Me, M=Zr 9, Hf 10; R=CH 2Ph, M=Ti 11, Zr 12, Hf 13), [ZrCp′ 2(CH 2Ph) 2] 14 and [ZrCpCp′(CH 2CMe 2Ph) 2] 17. A Similar reaction of 5 with 1 equiv. of Mg(CH 2Ph)Cl gave the monobenzyl compound [ZrCpCp′Cl(CH 2Ph)] ( 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.