Titanium (IV) and zirconium (IV) chloride complexes on the base of chiral tetraaryl-1,3-dioxolane-4,5-dimetanol ligands in the polymerization of ethylene: The promoting role of lithium and magnesium chloride

Coordination compounds of titanium (IV) and zirconium (IV) with tetra-aryl-1,3-dioxolan-4,5-dimethanol (1,2) derivatives were synthesized and characterized by NMR- and IR-spectroscopy and X-ray crystallography. It was demonstrated that titanium dichloride complexes (5–6, 9–12) when treated with MAO, TMA or TIBA are inactive in ethylene polymerization catalysis. However, these compounds become catalytically active in presence of lithium or magnesium chlorides. It was found that the magnitude of the resulting catalytic activity correlates with the following factors: mode of non-transition metals chlorides introduction to the reaction mixture, the nature of activator, and its overall amount. Resulting catalytic activity varied between 54 and 3500 kg PE/mole Ti٠h٠bar. Formed polymer was a linear polyethylene of high and ultrahigh molecular weight (over 5.95 105 g/mole) with high polydispersity index. Possible mechanisms of lithium and magnesium chlorides ability to promote the catalytic process were proposed.