Structural and ethylene oligomerization studies of chelating (imino)phenol Fe(ii), Co(ii) and Ni(ii) complexes: an experimental and theoretical approach

Abstract

Experimental and theoretical data indicate that the stability and metal charge of N^O Fe(ii), Co(ii) and Ni(ii) complexes control their catalytic activities in ethylene oligomerization reactions.

Chromium-Based Complexes Bearing N-Substituted Diphosphinoamine Ligands for Ethylene Oligomerization

“…There are primarily two types of ethylene oligomerization: nonselective oligomerization and selective tri/tetramerization. , The traditional ethylene oligomerization is nonselective, which mostly produces a wide range of oligomers, and the separation of the corresponding components from the product mixtures requires intensive energy. The most representative nonselective oligomerization was based on the iron/nickel (Fe/Ni)-based catalyst systems, which mainly produced the multicomponent oligomers with the Schulz–Flory distribution. − However, the selective ethylene tri/tetramerization can directly produce 1-hexene and 1-octene with high selectivity, which has attracted extensive research interest from both academia and industry. In particular, chromium-based catalysts have been widely studied due to their superior selectivity of 1-octene and 1-hexene in comparison with the other metal-based catalysts (Fe-, Co-, and Ni-based). − …”

“…The most representative nonselective oligomerization was based on the iron/nickel (Fe/Ni)-based catalyst systems, which mainly produced the multicomponent oligomers with the Schulz–Flory distribution. 11 − 13 However, the selective ethylene tri/tetramerization can directly produce 1-hexene and 1-octene with high selectivity, which has attracted extensive research interest from both academia and industry. In particular, chromium-based catalysts have been widely studied due to their superior selectivity of 1-octene and 1-hexene in comparison with the other metal-based catalysts (Fe-, Co-, and Ni-based).…”

Ethylene Oligomerization Catalyzed by Different Homogeneous or Heterogeneous Catalysts

“…Usually, the activity of iron catalysts is about one order of magnitude higher than that of cobalt catalysts [92]. At the same time, iron has the advantages of large reserves, cheapness, and environmental friendliness, which makes iron catalysts have broad application prospects [93]. In recent years, research on iron-based catalysts for ethylene oligomerization has mainly focused on ligands [94][95][96], which could be classified into NNN, NN, NNOO, NNO, and NNNNOO by the element attached to Fe in the ligand.…”

“…Makhosonke Ngcobo et al [93] synthesized Fe(II) complex of bidentate and tridentate (imino)phenol ligands bearing quinoline motifs (Figure 8). Using chlorobenzene as solvent, complex 8 undergoes ethylene oligomerization reaction under the activation of EtAlCl 2 .…”

Six-coordinated nickel(ii) complexes with benzothiadiazole Schiff-base ligands: synthesis, crystal structure, magnetic and HFEPR study

“…Most of the mononuclear complexes are characterized by a distorted octahedron, due to the geometry restrictions of the two tridentate ligands. A majority of the reports provided only crystallographic information, 12 some offer insights into bioactivity, 13,14 catalysis 15,16 or spectroscopic characteristics. 17 Notably, only a limited number of publications include magnetic measurements.…”