Titanium (IV) complexes stabilized by 2,6-bis-(α,α′-diphenyl(hydroxy)methyl)-pyridine: Catalytic activity in olefin polymerization and impact of lithium and magnesium chlorides

Abstract

A series of mono- and bi-nuclear complexes were synthesized by combining 2,6-bis-(α,α′-diphenyl(hydroxy)methyl)-pyridine and halide or alkoxide Ti(IV) derivatives. Crystal structures of synthesized products were determined. It was demonstrated that individual complexes 2–5 are active in ethylene and 1-hexene polymerization only in the presence of Et2AlCl/Bu2Mg binary co-catalyst. The systems formed from the lithium or magnesium salts of 2,6-bis(α,α′-diphenyl(hydroxy)methyl)-pyridine and TiCl4, containing respective Ti complexes and reaction byproducts (LiCl or MgCl2), are able to catalyze ethylene polymerization when activated by methylalumoxane or trimethylaluminum (TMA). The highest efficiency of catalysis was observed in the presence of binary co-catalysts Et2AlCl/Bu2Mg. The results of this study show the unique ability of Li and Mg chlorides to improve the catalytic ability of post-metallocene pre-catalysts.