Ethylene oligomerization using iron complexes: beyond the discovery of bis(imino)pyridine ligands

Abstract

Since the discovery that bis(imino)pyridine ligands are able to confer high activities in ethylene oligomerization and polymerization to their iron complexes, considerable attention has been focused on catalyst design for these reactions and this research constitutes an ever-growing area in molecular catalysis. The tuning of the ligand structures and properties, and thus of catalysts, generally represents the basis for subsequent work contributing to process development and industrialization. Significant effort is therefore devoted to generate structural diversity in order to access the required catalyst stability and selectivity. This feature article outlines nitrogen-containing ligands that have been developed for the iron-catalyzed oligomerization of ethylene since the seminal discovery of the properties of bis(imino)pyridine ligands.

Role of Homogeneous Catalysis in Oligomerization of Olefins : Focus on Selected Examples Based on Group 4 to Group 10 Transition Metal Complexes

“…lt seems that operating this kind of highly active catalytic system is still challenging and involve the development of novel approach to resolve the technical challenge [112]. Detailed recent reviews caver ali the complex modifications that have been studied [113,114], but also bring to the foreground severa! limitations of the ironcatalyzed ethylene oligomerization .…”

“…ln comparison, bidentate N,N neutra! ligands as pyridine-imine [117] or quinoline-imine [118] on iron(ll) precursors have also been investigated [113] and generally led to lowly active or inactive catalysts towards ethylene in presence of MAO ( Figure 20) . IFPEN was interested in the development of mono-anionic tridentate ligand and obtained N,NH,N ligands based on a 1,2-dihydro-1,10-phenanthroline scaffold from condensation of 2-acetylpyridine with 8-aminoquinoline derivatives [119].…”

Unprecedented Comonomer Dependence of the Stereochemistry Control in Pd‐Catalyzed CO/Vinyl Arene Polyketone Synthesis

“…[30] Iminopyridines are versatile bidentate ligands that can be easily prepared by condensation of the appropriate pyridine carbonyl compound with the desired amine. [31][32][33] Post-functionalization can also be performed by using,f or example, Stille [34] or Kumada [35] coupling at the pyridine ring. In catalysis, the relevant late transition metal complexes have been used, amongst others, in alkene oligo-and polymerization, [36] and in af ew examples for polyketone synthesis.…”

Recent advances in Ni-mediated ethylene chain growth: Nimine-donor ligand effects on catalytic activity, thermal stability and oligo-/polymer structure

“…By contrast, pyridinylimine-based N^N-nickel pre-catalysts, in the main, promote the conversion of ethylene to α-olefins with the ligand structure, substitution effects and process conditions playing an important role on the catalytic activity and product distribution [24,25,29]. Elsewhere, Braunstein and co-workers have made significant contributions in the field of catalytic ethylene oligomerization [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] and, in particular, with regard to the preparation and application of P^N [30][31][32]34,36], P^P [38,40], N^P^N [37] and SHOP-type [35,38] nickel complexes for olefin oligomerization. In general, however, it still remains difficult to achieve performance characteristics that can compete with industrial catalysts.…”