Coordination compounds of titanium (IV) and 2-hydroxymethyl-phenol derivatives: Their synthesis, structure and catalytic activity in ethylene and 1-hexene polymerization

• Ti and Ti–Li complexes bearing saligenin-type [O,O]2− ligands were synthesized.
• Complexes, activated by {Et2AlCl + Bu2Mg}, exhibited moderate to high activities toward ethylene and 1-hexene polymerization.
• Magnesium chloride, obtained by reaction MgBu2 + 2AlEt2Cl, can promote the catalytic process.

A series of titanium complexes LTiCl2·(iPrOH)212-18 and heterobimetallic complex L2Ti·iPrOLi·THF 19 bearing saligenin-type [O,O]2- ligands 6-11 were synthesized in high yields from Cl2Ti(OiPr)2 or LiTi(OiPr)5. X-ray structure analyses for 15 and 19 revealed that these complexes adopt a distorted octahedron or distorted tetragonal pyramid geometry. When activated by binary activator {3Et2AlCl + Bu2Mg}, complexes 12-19 exhibited moderate to high activities toward ethylene and 1-hexene polymerization, giving high molecular weight polymers with broad molecular weight distributions. The results of this study show the unique ability of Li and Mg chlorides to improve the catalytic ability of post-metallocene pre-catalysts.

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