Synthesis, Characterization, and Ethylene Oligomerization of Nickel Complexes Bearing N-((Pyridin-2-yl)methylene)quinolin-8-amine Derivatives

Abstract

A series of nickel complexes ligated by N-((pyridin-2-yl)methylene)quinolin-8-amine derivatives were synthesized by one-pot reaction of 8-aminoquinolines, 1-(pyridine-2-yl) ketones, and nickel halides and characterized by elemental and spectroscopic analyses along with X-ray diffraction analyses. These nickel complexes exhibit two kinds of structures, namely, dimeric with octahedral-coordinated geometry and monomeric with distorted trigonal-bipyramidal geometry, in their solid states. Activated by Et 2 AlCl, these Ni(II) complexes exhibited good to high catalytic activities for ethylene oligomerization, and activity up to 4.9 × 10 7 g mol -1 (Ni) h -1 was observed in the catalytic system with Cy 3 P as auxiliary ligand. The steric and electronic influence of the substituents as well as the influence of different catalytic conditions was carefully investigated. In particular, the correlations between reactivity and auxiliary R 3 P ligands were examined.

Synthesis, characterization and ethylene oligomerization behavior of 2-(chloro-substituted-1H-benzoimidazol-2-yl)-6-(1-aryliminoethyl)pyridylnickel dihalides

“…Extensive investigations for new procatalysts of various late-transition metal complexes have been conducted [8], and nickel complexes bearing bidentate [9][10][11][12][13][14][15][16][17][18][19] or tridentate ligands [20][21][22][23][24] have been the focus of much research. Beyond our efforts for iron procatalysts in ethylene reactivity [25,26], some nickel procatalysts were also investigated and possessed good activities [27][28][29][30][31]. More recently, the metal complexes ligated by 2-(benzimidazol-2-yl)-6-(1-aryliminoethyl)pyridines have been explored [32][33][34][35][36][37][38], and the metal complexes ligated by 2-(1-alkylbenzimidazol-2-yl)-6-(1-aryl-iminoethyl)pyridines (model A, Scheme 1) [32][33][34][35] possessed lower activity than their analogs bearing 2-(1H-benzimidazol-2-yl)-6-(1-aryliminoethyl)pyridines (model B, Scheme 1) [36][37][38].…”

2-(1-Aryliminoethylidene)quinolylnickel(II) dibromides: Synthesis, characterization and ethylene dimerization capability

“…Upon changing the Al/Ni molar ratio, the catalytic activities of C3 initially increased and then decreased and the selectivity for a-olefins varied from 90.1% to 96.2%. Increasing the reaction temperature resulted in a considerable reduction in activity (entries 4 and 7e9 in Table 3), which might be caused by the instability of the active species or possibly a lower concentration of ethylene in the reaction solution at the elevated reaction temperature [40,55,57]. On increasing the temperature up to 50 C, much lower activity resulted, indicating decomposition of the nickel active species, but with higher selectivity for the a-olefins.…”

Iron(II) and cobalt(II) complexes bearing N-((pyridin-2-yl)methylene)-quinolin-8-amine derivatives: Synthesis and application to ethylene oligomerization

“…However, those compounds were not stable well for purification [11,13], one-pot template synthesis was employed in the synthesis of the Fe(II) and Co(II) complexes [14]. Closer to this work, their nickel analogues were synthesized using nickel template reaction [11].…”

“…However, those compounds were not stable well for purification [11,13], one-pot template synthesis was employed in the synthesis of the Fe(II) and Co(II) complexes [14]. Closer to this work, their nickel analogues were synthesized using nickel template reaction [11]. Similarly, the template synthetic reaction of the 8-aminoquinoline derivative, pyridine-2-aldehyde derivative and FeCl 2 Á 4H 2 O or CoCl 2 were carried out in presence of acetic acid to afford the corresponding complexes (Scheme 2).…”

“…Actually the nickel complexes bearing N-((pyridin-2-yl)methylene)-quinolin-8-amine derivatives were synthesized and performed high catalytic activity in ethylene oligomerization [11]. Extensively, their Fe(II) and Co(II) analogues were synthesized in similar procedure.…”