A series of titanium complexes bearing [ONX] tridentate ligands have been synthesized and characterized. The complexes containing sulfur or phosphine donors showed high activity in the copolymerization of ethylene with 9-decen-1-ol (up to 1.3 x 10(8) g polymer (mol Ti)(-1) h(-1)) with an incorporation ratio of up to 8.8 mol %. Moreover, they have also shown excellent capability for copolymerization of ethylene with AlBu3i (or tert-butylchlorodimethylsilane) pretreated 4-penten-1-ol, omega-alkenoic acid, and omega-alkenoic ester, as well as unprotected tertiary amine.