New titanium complexes 5−8 with two indolide−imine chelate ligands [7-(RNCH)C8H5N]2TiCl2 (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, Mw/Mn 1.09−1.14; 7, Mw/Mn 1.05−1.23). On the other hand, at −10 °C complex 8 afforded monodisperse polyethylenes (Mw/Mn 1.12−1.25), with exceptionally high activities for a living ethylene polymerization (TOF: maximum 1155 min-1 atm-1). Using complex 7/MAO catal...