Bimetallic (Iron or Cobalt) Complexes Bearing 2-Methyl-2,4-bis(6-iminopyridin-2-yl)-1H-1,5-benzodiazepines for Ethylene Reactivity

Abstract

A series of bimetallic (ferrous and cobaltous) complexes ligated by 3,3-dihydro-2-methyl-2,4-bis(6iminopyridin-2-yl)-1H-1,5-benzodiazepines were synthesized and evaluated as catalysts for ethylene oligomerization and polymerization with high activity and R-olefin selectivity in the presence of modified methylaluminoxane (MMAO).

Iron-Based and Cobalt-Based Olefin Polymerisation Catalysts

“…While the 2,6-bis(imino)pyridine ligand frame has continued to lead the way, the past 10 years has also seen the development of alternative ligand sets that can act as compatible supports for iron and cobalt ethylene oligomerisation/polymerisation catalysts ( Table 4 ) [46,50,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209] ; active catalysts based on bimetallic iron and cobalt precatalysts have also started to emerge ( Table 5 ) [54,210,211,212,213,214,215] . In the main, these systems show lower activities than the prototype bis(imino)pyridine-based catalysts, although several of these systems have significantly started to approach their catalytic performances (e.g.…”

Iron(III) complexes bearing 2-(benzimidazole)-6-(1-aryliminoethyl)pyridines: Synthesis, characterization and their catalytic behaviors towards ethylene oligomerization and polymerization

“…Increase the Al/Fe molar ratio to 1000 and 1500 led to lower activity (entries 3-4 in Table 3). This observation could be traced to the impurities in commercial MAO such as alkyl aluminum, which led to the deactivation of active catalytic sites [48]. If the reaction temperature was elevated to 40°C, it resulted in a sharp decrease of activity (entry 5 in Table 3), which is possible due to the decomposition of active species and lower ethylene solubility at higher temperature [7,21], but the oligomer distribution was not changed evidently.…”

“…Extensive research on bis(imino)pyridyl iron complexes has been focused on understanding the active species or intermediates [18][19][20][21][22][23][24][25], controlling the products of polymers or oligomers as well as improving the catalytic activities through adapting steric and electronic characteristics of the complexes [26][27][28][29][30][31][32][33]. Apart from ferrous catalysts ligated by bis(imino)pyridines, a few models of iron catalysts were reported [34][35][36][37][38][39], but the iron complexes bearing 2-imino-1,10-phenanthroline [40][41][42], 2-benzimidazole-6-iminopyridines [43][44][45], 6-(quinoxalin-2-yl)-2-iminopyridines [46], 2-benzoxazolyl-6-[1-(arylimino)ethyl]pyridines [47], 2-methyl-2,4-bis(6-iminopyridin-2-yl)-1H-1,5-benzodiazepines [48,49], 2-benzimidazole-1,10-phenanthrolines [50], 2-oxazoline/benzoxazole-1,10-phenanthrolines [51] and N-((pyridin-2-yl)methylene)-quinolin-8-amine derivatives [52] provided alternative models performing high catalytic activities [53]. Despite great interest in designing new iron(II) based catalysts, unstable catalytic activities of stored iron(II) catalysts were often observed, however, commonly within one-order or less than ten times.…”

Ethylene Oligomerizations by Diazene Bridged Ni(II) Catalysts Derived from Pyrazole-Scaffold-Based Binucleating Ligands with Alkyl and Aryl Pendant Arms

“…Compounds encompassing a bimetallic core may demonstrate explicit reactivity patterns for the conversion of olefin monomers into oligomers/polymers, which arise from a subtle interplay between the metals and the ligands. Currently, there is great interest in both bridged and non-bridged bimetallic late-first-row transition-metal coordination catalysts for the oligomerization/polymerization of olefins with definite electronic and steric modulations [2][3][4][5][6][7][8][9][10][11].…”