Synthesis and characterization of monocyclopentadienyl titanium and zirconium complexes bearing a chelating (chiral) ether side chain on the Cp ring

The compounds (eta 5(:eta 1)-C5H4CH2CH2OR)TiCl3 with R = Me (1a), menthyl(1b), and fenchyl (1c), but not with R = isobornyl, were synthesized from the reaction of TiCL4 and C5H4(CH2CH2OR)(SiMe3) in CH2Cl2. Intramolecular coordination of the ether moiety in these compounds is fluxional. From temperature-dependent NMR data in CD2Cl2 it was calculated that at room temperature about 30% of 1a is in a conformation in which the ether handle is coordinated; for the chiral derivatives 1b and 1c this figure is significantly lower. A similar reaction using ZrCl4(SMe2)(2) yields the dimer [(eta(5):eta(1)-C5H4CH2CH2OMe)ZrCl2(mu-Cl)](2) (2). Chiral zirconium analogues could not be prepared in this way. The reaction of the isobornyl ligand results in selective C-O bond scission and formation of sulfonium zirconate salts. Compound 2 was structurally characterized. Probably due to its poor solubility 2 is only a moderate Ziegler-Natta catalyst for the polymerization of ethylene.