Synthesis of a New Polydentate Ligand Obtained by Coupling 2,6-Bis(imino)pyridine and (Imino)pyridine Moieties and Its Use in Ethylene Oligomerization in Conjunction with Iron(II) and Cobalt(II) Bis-halides

Abstract

In this paper are described the synthesis, characterization, and coordinating properties of a new potentially pentadentate nitrogen ligand, CyAr2N5, that combines in the same molecular structure 2,6-bis(imino)pyridine and (imino)pyridine moieties. This ligand reacts with 1 or 2 equiv of anhydrous MCl2 (M = Fe, Co) to give paramagnetic mononuclear or homodinuclear complexes of the formula CyAr2N5MCl2 and CyAr2N5M2Cl4. In the dinuclear complexes, one metal center is five-coordinate, while the other is four-coordinate. Ligand and metal complexes have been characterized, both in the solid state and in solution, by a variety of techniques, including single-crystal X-ray diffraction analyses, magnetic susceptibility determinations, IR, vis−NIR, 1H NMR, and X-band EPR spectroscopies. On activation by methylaluminoxane (MAO) in toluene, the FeII and CoII complexes generate effective catalysts for the oligomerization of ethylene to α-olefins with productivities and Schulz−Flory parameters depending on the type and...