Highly linear polyethylenes tailored with 2,6-bis[1-(p-dibenzo-cycloheptylarylimino)ethyl]pyridylcobalt dichlorides

Abstract

Bis(imino)pyridylcobalt dichlorides displayed high activities for ethylene polymerization, producing highly linear PEs with the vinyl end group as the major one.

Fusing Carbocycles of Inequivalent Ring Size to a Bis(imino)pyridine-Iron Ethylene Polymerization Catalyst: Distinctive Effects on Activity, PE Molecular Weight, and Dispersity

“…Through systematic variation of the steric and electronic properties of the ligand frame and in particular to the N-aryl groups, catalysts capable of generating highly sought-after materials such as α-olefins, linear PE waxes, and high-density polyethylene (HDPE) are all accessible [2,6,10]. Moreover, such targeted ligand manipulation has seen remarkable improvements to the temperature stability of the catalyst itself [5][6][7][8][9][11][12][13][14], a limitation often levelled against the first-generation catalysts [4,6]. Elsewhere, other types of neutral N,N,N-ligand skeleton such as N-[(pyridin-2-yl)-methylene]-8-amino-quinolines [15], 2-benzimidazolyl-6-imino-pyridines [16][17][18], 2,8-bis(imino)quinolines [19], and 2-imino-1,10-phenanthrolines [20,21] have witnessed some important developments [6][7][8].…”

6-Arylimino-2-(2-(1-phenylethyl)naphthalen-1-yl)-iminopyridylmetal (Fe and Co) Complexes as Highly Active Precatalysts for Ethylene Polymerization: Influence of Metal and/or Substituents on the Active, Thermostable Performance of Their Complexes and Resultant Polyethylenes

“…Two benzene substituents planes on naphthyl planes. Similar to many bis(imino)pyridine-cobalt complexes, the Co-N pyridyl bond length of two complexes [ Co3 : 2.050(4) Å; Co5 : 2.021(4) Å] is shorter than their exterior Co-N imino ones [2.170(4)-2.294(4) Å], indicating good donor property of the central pyridine [ 13 , 14 ]. Other selected bond lengths and angles are listed in Table 1 and more detail can be seen in Supplementary Materials .…”

“…Late-transition metal precatalysts have made great progress toward ethylene polymerization since the pioneering studies initiated by Brookhart and Gibson [ 1 , 2 , 3 , 4 , 5 , 6 ]. In addition to the α-diimino-nickel and palladium precatalysts [ 7 , 8 , 9 , 10 , 11 , 12 ], iron and cobalt precatalysts have showed a higher activity in ethylene polymerization and generated polyethylenes with highly linear structures [ 13 , 14 , 15 , 16 , 17 , 18 ]. However, the poor thermostability of iron and cobalt precatalysts and broad molecular weight distribution of obtained polyethylenes impeded further applications in the industry [ 19 , 20 ].…”

gem-Dimethyl-substituted bis(imino)dihydroquinolines as thermally stable supports for highly active cobalt catalysts that produce linear PE waxes

“…Indeed, numerous structural variations to the prototypical bis(arylimino)pyridine-metal precatalysts (A, Chart 1) have been performed including to the substituents belonging to the N-aryl groups and to the imino-carbon atoms. [18][19][20][21][22][23][24][25][26][27] As a further variable introduced by our group and others is the degree of ring strain present in the bis(imino)pyridine framework. Indeed by fusing one or two carbocyclic rings to the central pyridine unit, a wide variety of complexes have now been reported including those based on 1,8-diimino-2,3,4,5,6,7-hexahydroacridines (B, Chart 1), 28 2-(1-(arylimino)ethyl)-8-arylimino-5,6,7-trihydroquinolines (C), [29][30][31] 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethyl cyclopentapyridines (D, Chart 1) 32 and 2-(1-arylimino)ethyl-9arylimino-5,6,7,8-tetrahydro-cycloheptapyridines (E).…”