Synthesis, Characterization, and Catalytic Activities for the Polymerization of Olefins Promoted by Zirconium(III) and Titanium(III) Allyl Complexes

Abstract

The reaction of early-transition-metal halides MCl4 (M = Zr, Ti) with 2 equiv of the lithium allyl compound (tBuMe2SiCH)2CHLi·TMEDA in toluene produced the corresponding reduced complexes [{(tBuMe2SiCH)2CH}2M(μ-Cl)2Li·TMEDA] (M = Zr (1), Ti (2)), that were isolated as air-sensitive dark brown (Zr) and brick red (Ti) crystals in 48% and 42% yield, respectively. In addition, each reaction is associated with the formation of the dimer of the allyl ligand (3). Complexes 1 and 2 and dimer 3 were fully characterized spectroscopically, including solid-state X-ray diffraction studies. Complex 1 represents the first solid-state characterization for a Zr(III)−allyl complex. Oxidation of complexes 1 and 2 allows the formation of the corresponding neutral complexes {(tBuMe2SiCH)2CH}2MCl2 (M = Zr (4), Ti 5)), which were isolated as air-sensitive light yellow (Zr) and orange (Ti) powders in 23% and 11% yields, respectively. The allylic moieties in complex 5 showed a dynamic interconverting coordination from η3 to η1, c...