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-Bu'-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](mu-O)(OPri)(OPri)(2)}(2) [R = H (2a)], {Ti[ONSR](mu-S)(OPri)(2)}(2) [R=6-Me (2b)], Ti[ONSR] (OPri)(2) [R = 4-Me-6-Bu'(2c)], Ti[ONSR](2)[R = H (3a); R = 6-Me (3b)], {Ti[ONSR](mu- O)Cl-2}(2) [R = H (4a)], {Ti[ONSR](mu-S)Cl-2}(2) [R = 6-Me (4b)], and Ti[ONSR]Cl-2 [R = 4-Me-6-Bu' (4c)], respectively. Hydrolysis of 4c in THF solution containing a small amount of water produces the tetranuclear complex {Ti[ONSR](mu-O)}(4) [R = 4-Me-6-Bu' (5c)]. Complexes 2a-5c are characterized by H-1 NMR spectra and elemental analysis. The molecular structures of 2a, 21), 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.