Allylsilylcyclopentadienyl Group 4 metal complexes: synthesis, structure and reactivity

Abstract

(Allyldimethyl)silyl-substituted cyclopentadiene C5H5SiMe2(CH2CH /CH2) (1) and indene C9H7 /1-SiMe2(CH2CH /CH2) (2) were synthesized by reaction of SiMe2(CH2CH /CH2)Cl with NaC5H5 or LiC9H7, respectively. Metallation of 1 with n-BuLi and TlOEt gave the corresponding lithium 3 and thallium 5 salts. The disilylcylopentadienes C5H4 /1-SiMe3 /1-SiMe2(CH2CH /CH2) (6) and C5H4 /1,1-[SiMe2(CH2CH /CH2)]2 (7) were prepared by reaction of 3 with the corresponding chlorosilanes. Compound 7 reacted with TiCl4 to give the monocyclopentadienyl compound [Ti{h5 -C5H4SiMe2(CH2CH /CH2)}Cl3] (8), while 5 was used to prepare the titanocenes [Ti(h5 -Cp){h5 -C5H4SiMe2(CH2CH /CH2)}Cl2] (Cp /C5H4SiMe2(CH2CH /CH2) 9, C5H5 10, C5Me5 11) by reaction with the appropriate TiCpCl3 derivative. The related dicyclopentadienyl [Zr{h5 -C5H4SiMe2(CH2CH /CH2)}2Cl2] (12), [Zr(h5 -C5H5){h5 -C5H4SiMe2(CH2CH /CH2)}Cl2] (13), and indenyl [Zr(h5 -C5H5){h5 -C9H6SiMe2(CH2CH /CH2)}Cl2] (14) zirconium derivatives were isolated by reaction of ZrCl4 and Zr(h5 -C5H5)Cl3 /DME with the lithium salts 3 and 4, respectively. Alkylation of the metallocene complexes using MeLi, MgMeCl, Mg(CH2Ph)Cl and Mg(CH2Ph)2(THF)2 afforded the monomethyl titanium [Ti(h5 -C5H5){h5 -C5H4SiMe2(CH2CH /CH2)}ClMe] (15) and the dialkyl cyclopentadienyl [M(h5 -C5H5){h5 -C5H4SiMe2 (CH2CH /CH2)}R2] (R /Me, M /Ti 16, Zr 18; R /CH2Ph, M /Ti 20, Zr 22), [Zr{h5 -C5H4SiMe2(CH2CH /CH2)}2R2] (R /Me 17, CH2Ph 21) and indenyl derivatives [Zr(h5 -C5H5){h5 -C9H6SiMe2(CH2CH /CH2)}R2] (R /Me 19, CH2Ph 23). The molecular structure of 11 was studied by X-ray diffraction methods. The reactions of the dialkyl derivatives with B(C6F5)3 were monitored by NMR spectroscopy at variable temperature. The catalytic activity of the dichloro zirconium complexes in the presence of methylalumoxane (MAO) for ethylene polymerization was determined.