Asymmetric binuclear titanocenes linked by alkyl benzyl ethers: Synthesis, characterization and use as catalysts for ethylene polymerization

A series of novel asymmetric binuclear titanocenes linked with alkyl benzyl ethers p-[(C5H5TiCl2)C5H4CH2]C6H4O(CH2)n[C5H4(TiCl2C5H5)] (n = 2–5) (13–16) have been synthesized by treating p-(LiC5H4CH2)C6H4O(CH2)n(C5H4Li) (n = 2–5) (9–12) with C5H5TiCl3. The new complexes have been characterized by elemental analysis and NMR spectra. Their catalytic activity for ethylene polymerization was investigated in the presence of aluminoxane (MAO). The results show that 13–16 are efficient catalysts for producing polyethylene (PE) with a broad molecular weight distribution (MWD). Their catalytic activity is highly dependent on the length of the alkyl chain and the polymerization conditions. A longer alkyl chain increases the catalytic activity, whereas the molecular weight of the produced polyethylene decreases.