2-[1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-aryliminoethyl]pyridyl cobalt dichlorides: Synthesis, characterization and ethylene polymerization behavior

A series of 2-[1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-aryliminoethyl]pyridyl cobalt(II) dichloride complexes (Co1–Co5) were prepared and characterized by elemental and spectroscopic analysis. The molecular structures of the representative cobalt complexes Co1 and Co4 were determined by single-crystal X-ray diffraction, and revealed a pseudo-square-pyramidal geometry around each cobalt atom. Upon activation with either MMAO or MAO, all cobalt pre-catalysts exhibited high activities toward ethylene polymerization and produced polyethylene products with narrow molecular distributions (1.98–3.61) and molecular weights in the range 72.3–665 kg/mol; the latter is higher than any other molecular weight of polyethylenes obtained by previous cobalt pre-catalysts. Reaction parameters and the nature of the ligands were investigated for their influence on the resultant catalytic activities and properties of the polyethylene products obtained.

Graphical abstractThe 2-[1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-aryliminoethyl]pyridyl cobalt (II) dichloride complexes, upon activation with either MMAO or MAO, exhibited high activities toward ethylene polymerization and produced polyethylenes with narrow molecular distributions (1.98–3.61) and molecular weights in the range 72.3–665 kg/mol.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New bis(imino)pyridylcobalt dichloride complexes. ► High ethylene polymerization. ► Polyethylene with narrow molecular polydispersity. ► Polyethylenes with high molecular weights. ► Highly linear polyethylenes.