Iminopyridine Copper Complex-Based Catalysts for 1,3-Dienes Stereospecific Polymerization

Some novel copper complexes are synthesized by reacting copper(II) dichloride and copper(II) dibromide with a series of pyridyl-imine ligands differing in the nature of the substituents at the iminic carbon and at the imino nitrogen atom. All the complexes are characterized by analytical and infrared data: for some of them single crystals are obtained, and their molecular structure is determined by X-ray diffraction. The complexes are combined with methylaluminoxane (MAO) for the polymerization of 1,3-dienes (i.e., 1,3-butadiene and isoprene) obtaining active and selective catalysts and, in case of isoprene, polymers with quite unusual structures, i.e., predominantly alternating cis-1,4-alt-3,4 structures containing cis-1,4 units sequences within the polymer chain.