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

Mixed bent sandwich titanium(IV) complexes containing the donor-substituted [2-(diisopropylamino)ethyl]cyclopentadienyl (C5H4CH2CH2NiPr2 = Cp(N)) ligand are described. The highly moisture-sensitive metallocene dichloride (C5H4CH2CH2NNiPr2)(C(5)H(4)SiMe(3))TiCl2 (1) was synthesized by reaction of Cp(N)Li with Cp(S)TiCl(3) (Cp(S) = C(5)H(4)SiMe(3)) Complex 1 reacts with one equivalent of HCl with protonation of the amino group to give the air- and water-stable metallocene dichloride-hydrochloride [(C5H4CH2CH2N(H)iPr(2)) (C(5)H(4)SiMe(3))TiCl2]Cl-+(-) (2) The structure of 2 was determined by a single-crystal X-ray diffraction study. Compounds 1 and 2 are precursors for ethylene polymerization catalysts. The reaction of 2 with one equivalent of Na+B[3,5-(CF3)(2)C6H3](-)(4) afforded the borate [(C5H4CH2CH2N(H)iPr(2))(C(5)H(4)SiMe(3))TiCl2]B-+[3,5-(CF3)(2)C6H3](-)(4) (3) The dimethyl compound (C5H4CH2CH2NiPr2)(C(5)H(4)SiMe(3))TiMe(2) (4) was obtained by reaction of 1 with two equivalents of methyllithium. The diphenoxy complex (C5H4CH2CH2NiPr2)(C(5)H(4)SiMe(3))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.