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

Potent inhibition of protein tyrosine phosphatases by copper complexes with multi-benzimidazole derivatives

“…In solid, the IR spectra of TDB, NTB, EDTB, EGTB, and DTPB give the C=N stretching frequencies in the range of 1,642-1,619 cm -1 , while the C=N stretching vibrations of the complexes 1-5 shifted toward lower frequencies between 1,627 and 1,604 cm -1 with weak intensities which indicates the effective coordination between the imidazole nitrogen atom and the copper (Achar et al 2010;Hao et al 2010). The bands appearing at 3,552-3,381 and 3,234-2,903 cm -1 are assigned to hydrogen band O-H, N-H and C-H (Hao et al 2010); 1,348w, 1,316w and 1,270m regions belong to C-N stretching vibration (Krishnakumar and Ramasamy 2005); 740 cm -1 designated to phenyl ring out-of-plane bending vibration (Merlino et al 2007); and 563-610 cm -1 designated to Cu-N stretching vibration (Lu et al 2003).…”

“…The bands appearing at 3,552-3,381 and 3,234-2,903 cm -1 are assigned to hydrogen band O-H, N-H and C-H (Hao et al 2010); 1,348w, 1,316w and 1,270m regions belong to C-N stretching vibration (Krishnakumar and Ramasamy 2005); 740 cm -1 designated to phenyl ring out-of-plane bending vibration (Merlino et al 2007); and 563-610 cm -1 designated to Cu-N stretching vibration (Lu et al 2003). The EAs suggest that the main structures for complexes 1-5 are given in Fig.…”

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

“…50 The analogs 160 and 161 revealed high activity towards ethylene oligomerization; some polyethylene waxes were also formed. [80][81][82] The activity order R = H 78 > R = Me 79 > R = iPr 77 was observed due to the electronic influence exerted by the substituents. When the benzimidazole contained different substituents such as Me or Cl, the activity of 162 and 163 versus 160a exhibited slight differences.…”

“…78 Our group has systematically studied the ethylene polymerization and oligomerization characteristic of a number of N,N, N-tridentate pyridyl iron(II) and cobalt(II) catalysts with different ligand frameworks (Scheme 27). 20,50,[80][81][82][83][84][85] The iron pre-catalyst 158 exhibited high activity for ethylene oligomerization in the presence of MAO with butene as the major product at atmospheric pressure. 50 Similarly, the cobalt precatalyst 159 also exhibited high activity for ethylene oligomerization in the presence of MMAO with butene as the major product at atmospheric pressure, for example, the typical activity of 158 was 1.67 × 10 5 g (mol Co) −1 h −1 for oligomerization and the C4 percent was 96.4%.…”

Understanding the role of aluminum-based activators in single site iron catalysts for ethylene oligomerization

“…Methylaluminoxanes (MAO) [1][2][3][4] have been widely used as activators of ethylene oligomerization and polymerization iron-based catalysts, especially those belonging to the bis(imino)pyridine family, affording highly productive catalytic systems [5][6][7][8][9][10][11][12]. As high MAO/metal ratios are required, leading to high costs, considerable efforts have been undertaken to replace them in oligomerization reactions [13][14][15]. This requires a good understanding of the activation process of the catalyst.…”