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

Abstract

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 × 106 mol ethylene/mol Fe. Product purities are high, with 1-hexene and 1-octene exceeding 99% purity in most examples.