Syntheses, Reactions, and Ethylene Polymerization of Titanium Complexes with [N, O, S] Ligands

Tridentate dianionic arylsulfide ligands [2-(2-SC6H4)NCHC6H4O]2− (La), [6-Me-2-(2-SC6H4)NCHC6H3O]2− (Lb), and [4-Me-6-But-2-(2-SC6H4)NCHC6H2O] 2− (Lc) have been synthesized. Reactions of Ti(OPri)4 and TiCl4 with the tridentate dianionic arylsulfide ligands (La−Lc) afford monomeric and dimeric titanium complexes {Ti[ONSR](μ-O)(OPri)2}2 [R = H (2a)], {Ti[ONSR](μ-S)(OPri)2}2 [R = 6-Me (2b)], Ti[ONSR](OPri)2 [R = 4-Me-6-But (2c)], Ti[ONSR]2 [R = H (3a); R = 6-Me (3b)], {Ti[ONSR](μ-O)Cl2}2 [R = H (4a)], {Ti[ONSR](μ-S)Cl2}2 [R = 6-Me (4b)], and Ti[ONSR]Cl2 [R = 4-Me-6-But (4c)], respectively. Hydrolysis of 4c in THF solution containing a small amount of water produces the tetranuclear complex {Ti[ONSR](μ-O)}4 [R = 4-Me-6-But (5c)]. Complexes 2a−5c are characterized by 1H NMR spectra and elemental analysis. The molecular structures of 2a, 2b, 2c, 3b, and 5c have been characterized by single-crystal X-ray diffraction analyses. The effect of steric hindrance on the structure of products has been investigated. When activated by excess methylaluminoxane (MAO), 2a−2c, 4a−4c, and 5c can be used as catalysts for ethylene polymerization and exhibit moderate to good activities.