Synthesis of a novel bis(imino)pyridyl iron complex and its opplecation in oligomerization of ethylene

A novel 2, 6-bis (imino) pyridyl iron complex bearing flouoro and methyl substituents has been synthesized and used for ethylene oligomerization. The activity of this complex could reach 1.8 × 10⁷ g/mol Fe·h when used for ethylene oligomerization, and most of the resulting products(> 90%) are low-molar-mass oligomers, such as 1-butene, 1-hexene and 1-octene. The catalytic activities are influenced greatly by reaction temperature. With increase of reaction temperatures, the activities decrease rapidly and more low-molecular-weight products are produced.The distribution of obtained oligomers is almost invariant with the Al/Fe molar ratio, but the catalytic activities increase rapidly at first and then decrease because of the deficient protection provided by small steric bulk of bluoro at ortho position of aryl rings. As a result the chain transfer to MAO occurs more easily. Another three complexes have also been synthesized for comparison. Adapted ortho-and para-substituents on aryl rings are the main effects on oligomerization activities and distributions of oligomers for 2,6-bis (imino) pyridyl iron complexes.