Syntheses, characterization, and ethylene polymerization of titanium and zirconium complexes with [N, O] ligands

Abstract

Bidentate monoanionic ligands 2-(benzo[d]thiazol-2-yl) phenol (La), 2-(benzo[d]thiazol-2-yl)-6-methylphenol (Lb), 2-(benzo[d]thiazol-2-yl)-6-tert-butyl-4-methylphenol (Lc), 2-(benzo[d]thiazol-2-yl)-6-chlorophenol (Ld), and 2-(benzo[d]thiazol-2-yl)-4-chlorophenol (Le) have been synthesized. Reactions of TiCl4(THF)2 or ZrCl4 with La-Le afford the corresponding titanium complexes Ti[ON]2(R)Cl2 [R = 6-Me (2b); R = 4-Me-6-Bu(t) (2c)], and zirconium complexes Zr[ON]2(R)Cl2 [R = H (3a); R = 6-Me (3b); R = 4-Me-6-Bu(t) (3c); R = 6-Cl (3d); R = 4-Cl (3e)], and Zr[ON(R)]HCl4 x THF [R = 6-Me (4b)], respectively. Complexes 2a-4b were characterized by IR, 1H NMR spectra and elemental analysis. The molecular structures of La, 2b, 2c, 3b, 3c and 4b have been characterized by single-crystal X-ray diffraction analyses. The effect of steric hindrance and the coordination metal on the structure of the products has been investigated. When activated by excess methylaluminoxane (MAO), 2b and 2c, 3a-3e and 4b can be used as catalysts for ethylene polymerization and exhibit moderate to good activities.