Synthesis and polymerization behavior of tetrahydro-2-methylbenzindenyltitanium and zirconium compounds

Abstract

In order to further our study of the bis(2-methylbenz[ e]indenyl)zirconium dichloride catalyst system, we have synthesized the analogous tetrahydro-2-methylbenz[ e]indene ligand ( 4). In the process of synthesizing 4, we have found that the structural isomer tetrahydro-2-methylbenz[ f]indene ( 5) is also formed. This has been confirmed by the synthesis of a series of dimethyl ( 6 and 7), methyl-phenyl ( 8), and titanium trichloride derivatives ( 11 and 12) of the parent indenes 4 and 5. The new ligand systems 4, 6, 7, and 8 were converted to the analogous unbridged zirconocene dichloride complexes 13, 14, 15, and 16. The precursors were then activated with either methylaluminoxane (MAO) or triphenylcarbenium tetrakis(pentafluorophenyl)borate (trityl) and used as catalysts for the polymerization of ethylene and propylene. All zirconocene complexes were highly active for the polymerization of ethylene, and in some cases produced crystalline polypropylene at lower polymerization temperatures.