Nickel(II) complexes with imino-imidazole chelating ligands bearing pendant donor groups (SR, OR, NR2, PR2) as precatalysts in ethylene oligomerization

NNNO‐Heteroscorpionate nickel (II) and cobalt (II) complexes for ethylene oligomerization: the unprecedented formation of odd carbon number olefins

“…However, this mechanism much worse describes the distribution of products formed during the oligomerization of 1-hexene, because it requires the preferable β-C 2 H 5 elimination. The possible formation of odd carbon number olefins, as a result of side-reactions in the presence of the EtAlCl 2 , is not supported neither by literature [57,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] nor by experimental data (SI, Figure S51).…”

(Pyrazolyl)-(phosphinoyl)pyridine iron(II), cobalt(II) and nickel(II) complexes: Synthesis, characterization and ethylene oligomerization studies

“…In another related study, low catalytic activities in ethylene oligomerization reactions were reported for nickel metallodendritic catalysts in hexane solvent [41]. Similarly, ethylene oligomerization studies conducted in heptane catalyzed by nickel complexes bearing N-((1-methyl-1H-imidazol-2-yl) methylene)-2-(methylthio)ethanamine resulted in the formation of mainly C 4 (79%) and hexene (21%) albeit with lower catalytic activity (1.63 Â 10 6 g C2H4 (mol h) À1 ) compared to the same reaction conducted in toluene solvent (3.14 Â 10 6 g C2H4 (mol h) À1 ) [19].…”

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.…”