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  CpN) ligand are described. The highly moisture‐sensitive metallocene dichloride (C5H4CH2CH2NNiPr2)(C5H4SiMe3)TiCl2 (1) was synthesized by reaction of CpNLi with CpSTiCl3 (CpS  C5H4SiMe3). Complex 1 reacts with one equivalent of HCl with protonation of the amino group to give the air‐ and water‐stable metallocene dichloride‐hydrochloride [(C5H4CH2CH2‐N(H)iPr2)(C5H4SiMe3)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)2C6H3]4− afforded the borate [(C5H4CH2CH2N(H)iPr2)‐(C5H4SiMe3)TiCl2]+B[3,5‐(CF3)2C6H3]4− (3). The dimethyl compounds (C5H4CH2CH2NiPr2)(C5H4SiMe3)Time2 (4) was obtained by reaction of 1 with two equivalents of methyllithium. The diphenoxy complex (C5H4CH2CH2‐NiPr2)(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.