New Titanium Complexes Bearing Two Indolide−Imine Chelate Ligands for the Polymerization of Ethylene

New titanium complexes 5 − 8 with two indolide−imine chelate ligands [7-(RN CH)C 8 H 5 N] 2 TiCl 2 (R: 5, phenyl; 6, 2,6-difluorophenyl; 7, 2,4,6-trifluorophenyl; 8, pentafluorophenyl) were synthesized and investigated as ethylene polymerization catalysts. On activation with methylalumoxane (MAO), all of the complexes were active ethylene polymerization catalysts at 25 °C to produce linear polyethylenes. The catalytic activity (TOF) increased sharply with the number of fluorine atom in the ligand. In addition, complexes 5 − 8 potentially exhibit the characteristics of a living ethylene polymerization. Complexes 6 and 7 promoted room temperature living ethylene polymerization to produce polyethylenes having extremely narrow molecular weight distributions ( 6, M w / M n 1.09−1.14; 7, M w / M n 1.05−1.23). On the other hand, at −10 °C complex 8 afforded monodisperse polyethylenes ( M w / M n 1.12−1.25), with exceptionally high activities for a living ethylene polymerization (TOF: maximum 1155 min -1 atm -1 ). Using complex 7 /MAO catalyst system, a polyethylene- b -poly(ethylene- co -propylene) block copolymer was successfully synthesized.