Oligomerization of Ethylene Using New Iron Catalysts Bearing Pendant Donor Modified α-Diimine Ligands

Stoichiometric Schiff base condensations of sterically bulky primary amines with acenaphthenequinone yield isolable monoimines. In the presence of Fe or other transition metals, the remaining ketone reacts with a second primary amine bearing a pendent donor atom to give asymmetric, tridentate, α-diimine complexes. Upon activation with alumoxanes, these complexes are highly active for the oligomerization of ethylene to linear α-olefins, with turnover numbers (TONs) exceeding 2.5 × 10 6 mol ethylene/mol Fe. Product purities are high, with 1-hexene and 1-octene exceeding 99% purity in most examples.