Controlling the ethylene polymerization parameters in iron pre-catalysts of the type 2-[1-(2,4-dibenzhydryl-6-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl] pyridyliron dichloride

The ligand series 2-[1-(2,4-dibenzhydryl-6-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridines and the iron(II) chloride complexes thereof have been synthesized and characterized by elemental and spectroscopic analyses. The molecular structures of C1 and C2, determined by single-crystal X-ray diffraction analysis, confirmed a pseudo-square-pyramidal geometry at the iron center. Upon treatment with either MAO or MMAO, all iron pre-catalysts possessed good thermo-stability and exhibited high activities [up to 5.22 × 107 g mol-1(Fe) h-1] toward ethylene polymerization, producing highly linear polyethylene products. Optimization of the reaction parameters gave polyethylenes with narrow molecular weight distributions, indicating that single-site active species were formed; the molecular weights of the resultant polyethylenes could also be controlled.