Synthesis and application in high-pressure polymerization of a titanium complex with a linked cyclopentadienyl-phenoxide ligand

The ansa half-sandwich complex [eta(5):eta(1)-C5H4-C(CH3)(2)-2-C6H4O]TiCl2 (1) has been prepared using two different ways, a 'one-pot' synthesis and a synthesis via thermolysis of the Ti trichloride precursor [eta(5)-C5H4-C(C H3)(2)-2-C6H4OCH3]TiCl3 (3). When activated with methylaluminoxane (4) or t he cocatalyst system triisobutyl aluminum/[Me2PhNH](+) [B(C6F5)(4)](-) (5), complex 1 could be used as a catalyst in high-pressure, high-temperature p olymerization. The productivity of the catalyst system 1/4 in high-pressure polymerization of ethene is 400 t polymer mol(-1) Ti, while the productivi ty of catalyst system 1/5 is only 6 t polymer mol(-1) Ti. In ethene/1-hexen e copolymerizations productivity and molecular weights decrease with increa sing 1-hexene in the feed. The polymerization results were discussed and co mpared to results of high-pressure polymerization with the catalyst system Me2Si[IndH(4)](2)ZrCl2/4. (C) 2000 Elsevier Science S.A. All rights reserve d.