Ethylene oligomerization, homopolymerization and copolymerization by iron and cobalt catalysts with 2,6-(bis-organylimino)pyridyl ligands

Bi- and tri-dentate imino-based iron and cobalt pre-catalysts for ethylene oligo-/polymerization

“…The reader is directed to a raft of review articles that focus on early and some more recent developments. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] The main driving force for such studies is to access new highly branched polyethylene products, whilst getting away from the 20 more oxophilic nature of early transition metal systems. In the past half-dozen or so years, stable complex pre-catalysts that exhibit high thermal stability have been reported for both cobalt 20 and iron complexes.…”

“…Such low activity is probably due to the 25 formation of unstable active species, which given the greater open space available at the metal, tend to be more prone to coordinating with other species present in the system (leading to deactivation). The result of this poor performance is that less attention has been paid to bi-dentate iron/cobalt complex 30 pre-catalysts, although readily available iminopyridine derivatives have been used to form cobalt complexes, [27][28][29][30] which were found to exhibit high activity with selectivity toward dimerization. Following on from this, recent investigations involving the design of new N^N bi-dentate 35 ligands and the metal complexes thereof, have revealed promising results for ethylene polymerization.…”

Nickel(II) Complex Bearing Fluorine-substituted α-Diimine Ligand Immobilized in Fluorotetrasilicic Mica Interlayer as Heterogeneous Catalysts for Ethylene Oligomerization

“…Hideki KUROKAWA 1) , Ryota OGAWA 1) , Kazuhiro YAMAMOTO 2) , Tsutomu SAKURAGI 2) , Masa-aki OHSHIMA 1) , and Hiroshi MIURA Heterogeneous α-diiminenickel(II) catalysts were prepared by the direct reaction between nickel(II) ionexchanged fluorotetrasilicic mica and the ligand [Ph' _ N C(Me) _ C(Me) N _ Ph'; Ph' C6H5 _ , 2-FC6H4 _ , 4-FC6H4 _ , 2,4-F2C6H3 _ , and 2,4,6-F3C6H2 _ ]. When the prepared procatalysts were activated by a conventional alkyl aluminum compound, such as triethylaluminum or triisobutylaluminum, the high activity for ethylene oligomerization was readily obtained with the formation of linear α-olefins.…”

Oligomerization of Monoolefins by Homogeneous Catalysts

“…With a proper selection of the couples metal-ligand and metal-activators, it is possible to achieve either the selective dimerization of ethylene or its trimerization or even the tetramerization [4] associated with the trimerization of ethylene. Finally, thanks to the use of iron bis-iminopyridine complexes activated with aluminoxane, the dimerization of alpha olefins (C 3 to C 8 ) to linear dimers, which is known to be difficult, has been recently improved [5][6][7].…”