Synthesis and Characterization of Titanium(IV) Complexes Bearing Monoanionic [O^-NX] (X = O, S, Se) Tridentate Ligands and Their Behaviors in Ethylene Homo- and Copolymerizaton with 1-Hexene

A series of novel titanium(IV) complexes bearing monoanionic [O^-NX] (X = O, S, Se) ligands is designed by sidearm approach. These complexes were synthesized, characterized, and employed as catalysts in ethylene homo- and copolymerization. X-ray diffraction studies on these new compounds reveal a distorted octahedral coordination of the central metal with the three chlorine ligands in a mer disposition. In the presence of modified methylaluminoxane (MMAO), they exhibit moderate to high activity and afford highly linear polyethylene. Variation of the sidearm, including different heteroatom and substituents, proves to modulate both the catalytic activity and the molecular weight of the resulting polyethylene. The complexes also show excellent capability in copolymerization of ethylene with 1-hexene.