Prominent Spatial Structure and Synergistic Linkage Effects in Bimetallic Titanium Olefin Polymerization Catalysts

In this contribution, the binuclear Ti olefin polymerization catalyst 1,4-phenoxy{[Me2Si(C5H4)(2)]TiCl}(2) (Complex 2) was synthesized by the reaction of hydroquinone with [Me2Si(C5H4)(2)]TiCl2. Compared to mononuclear [Me2Si-(C5H4)(2)]TiCl2 (Complex 1), due to the synergistic effect of bimetals, Complex 2 was thermally more stable and showed higher activity up to 1.36 x 10(6) g/(mol(Ti) h) for ethylene polymerization at 120 degrees C. Remarkably, adding the phenoxy group in front of the metal center gives the catalyst a denser coordination environment, and the beta-H elimination reaction is slowed down, thereby increasing the molecular weight of the polymer. DFT calculations showed that the Ti-Cp distances in active species 2 were extended by 0.0S9 and 0.063 angstrom, respectively, compared to those in active species 1. This makes the space of the active center more spacious and easier to promote olefin polymerization. Consequently, the copolymer's 1-octene monomer incorporation rate reaches 16.21 mol %, with a fracture strain of 1140% and a stress recovery (SR) of 65%.