Ethylene polymerization by novel phenylenedimethylene bridged homobinuclear titanocene/MAO systems

Reaction of (o, m, p) disodium(phenylenedimethylene)dicyclopentadienide C₆H₄(CH₂C₅H₄Na)₂ with 2 equiv of (MeCp)TiCl₃ yields the phenylenedimethylene bridged binuclear titanocenes complexes (MeC₅H₄)TiCl₂](C₅H₄CH₂C₆H₄CH₂C₅H₄)(MeC₅H₄)TiCl₂] (3, 4, 5) in high yield, which were characterized by ¹H NMR and elemental analysis. They were used successfully as efficient catalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). The catalytic activities of 4 and 5 are somewhat higher than that of 3 and the molecular weight distributions (MWD = 4.8-6.2) of the polymers generated from the bimetallic catalytic systems are obviously higher than that obtained by conventional Cp₂TiCl₂.