Mixed bent sandwich titanium complexes with the [2-(diisopropylamino)ethyl]cyclopentadienyl ligand - catalysts for the polymerization of ethylene and the dehydrocoupling of phenylsilane

Article abstract of DOI:10.1002/cber.19961291218

Mixed bent sandwich titanium(IV) complexes containing the donor-substituted [2-{diisopropylamino)ethyl]cyclopentadienyl (C₅H₄CH₂CH₂NjPr₂ = Cp^N) ligand are described. The highly moisture-sensitive metallocene dichloride (C₅H₄CH₂CH₂NN;Pr₂)(C ₅H₄SiMe₃)TiCl₂ (1) was synthesized by reaction of Cp_NLi with Cp^STiCl₃ (Cp^S ≡ C₅H₄SiMe₃). Complex 1 reacts with one equivalent of HC1 with protonation of the amino group to give the air- and water-stable metallocene dichloride-hydrochloride [(C₅H₄CH₂CH₂-N(H)/Pr ₂)(C₅H₄SiMe₃)TiCl₂] ⁺ Cl^- (2). The structure of 2 was determined by a single-crystal X-ray diffraction study. Com-pounds 1 and 2 are precursors for ethylene polymerization catalysts. The reaction of 2 with one equivalent of Na⁺B[3,5-(CF₃)₂C₆H₃] ₄^- afforded the borate [(C₅H₄CH₂CH₂N(H)jPr ₂)-{C₅H₄SiMe₃)TiCl ₂rB[3,5-(CF₃)₂C₆H₃] ₄^- (3). The dimethyl compound (C₅H₄CM₂CH₂NJPr₂)(C ₅H₄SiMe₃)TiMe₂ (4) was obtained by reaction of 1 with two equivalents of methyllithium. The diphenoxy complex (C₅H₄CH₂CH₂-N/Pr_{2 2})(C₅H₄SiMe₃)Ti(OPh)₂ (5) was prepared analogously with a stoichiometric amount of lithium phenoxide. Compounds 4 and 5 show remarkable activity in the catalytic dehydrocoupling of phenylsilane. VCH Verlagsgesellschaft mbH, 1996.