(Pentamethylcyclopentadienyl)titanatrane: A new class of catalyst for syndiospecific polymerization of styrene

Abstract

A new type of catalyst for the syndiospecific polymerization of styrene, Cp*Ti(N(CH2CH2O)(3)) (3), was prepared by either the reaction of triethanolamine with Cp*TiCl3 in the presence of triethylamine or the reaction of (N(CH2CH2O)(3))TiCl with LiCp*. The former reaction route is more efficient in terms of yield and easy accessibility of a titanium starting compound. The X-ray analysis reveals that 3 exists in a monomeric form in the solid state and the Ti atom adopts essentially an eta(5) bonding posture with regard to the Cp* ring and a tetradentate bonding mode with regard to the triethanolateamine ligand via a transannular interaction from the bridgehead N atom to Ti. The compound 3, which is stable to air and heat and soluble in hydrocarbon solvents, shows very efficient catalytic activity for the syndiospecific polymerization of styrene in the presence of modified methylaluminoxane (MMAO) as cocatalyst.