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)C8H5N](2)-TiCl2 (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 (NIAO), all of the complexes were active ethylene polymerization catalysts at 25 degreesC 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 degreesC 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.