2008
DOI: 10.1002/app.28134
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Ethylene polymerization by (α‐diimine)nickel(II) complexes bearing different substituents on para‐position of imines activated with MMAO

Abstract: A series of (a-diimine)nickel(II) complexes [ArN 5 C(Nap)C 5 NAr]NiBr 2 (Nap 5 1,8-naphthdiyl, Ar 5 2,6-Me 2 C 6 H 3 , 3a; Ar 5 2,4,6-Me 3 C 6 H 2 3b; Ar 5 2,6-Me 2 -4-tBuC 6 H 2 , 3c; Ar 5 2,6-Me 2 -4-BrC 6 H 2 , 3d; Ar 5 2,6-Me 2 -4-ClC 6 H 2 , 3e; Ar 5 2,6-iPr 2 C 6 H 3 , 3f; Ar 5 2,4,6-iPr 3 C 6 H 2 , 3g; Ar 5 2,6-iPr-4-BrC 6 H 2 , 3h) have been synthesized, characterized, and investigated as precatalysts for ethylene polymerization in the presence of modified methylaluminoxane (MMAO). The substituents of … Show more

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Cited by 39 publications
(22 citation statements)
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“…The change in polymerization activity with the change of the ortho substituents at the arene moieties of the catalyst structures shows that the bulkier the substituents, the lower the polymerization activity. This result is compatible with the chain running mechanism [3][4][5][6][7][8][9][10][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] (Scheme 8) which suggests that the bulky substituents can hinder the monomers from reaching the active catalytic centers due to their interaction with the axial coordination sites of the metal centers resulting in lower activities. The influence of the substituent's size on the catalyst activity was higher in the case of nickel and zirconium catalysts.…”
Section: Methodssupporting
confidence: 72%
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“…The change in polymerization activity with the change of the ortho substituents at the arene moieties of the catalyst structures shows that the bulkier the substituents, the lower the polymerization activity. This result is compatible with the chain running mechanism [3][4][5][6][7][8][9][10][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] (Scheme 8) which suggests that the bulky substituents can hinder the monomers from reaching the active catalytic centers due to their interaction with the axial coordination sites of the metal centers resulting in lower activities. The influence of the substituent's size on the catalyst activity was higher in the case of nickel and zirconium catalysts.…”
Section: Methodssupporting
confidence: 72%
“…Chain running mechanism. [3][4][5][6][7][8][9][10][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Samples of the produced polyethylene by the nickel catalysts 4f, 5f, and 6f were analyzed by gel permeation chromatography (GPC). The aim was to study the effect of varying the bulk of the ortho substituents at the arene moieties on the molecular weight (MW) of the produced polyethylene and the molecular weight distribution (MWD).…”
Section: Methodsmentioning
confidence: 99%
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“…When a-diimines are used as donor-ligands forming d 8 square planar coordination complexes, reactions including ethylene dimerization [5], ethylene oligomerization [6], ethylene polymerization [7][8][9][10][11], propylene polymerization [12], 2-butene polymerization [13], butadiene polymerization [14], CO and vinyl arene copolymerization generating atactic polyketones [15], and the CAH activation of methane [16] and benzene [17] are observed. Specifically, transition metal catalysts containing coordinated a-diimine 3 have been used for the synthesis of epoxides [18], N-arylpyrroles [19], hetero-Diels-Alder adducts [19], aniline from the reduction of nitrobenzene [20], and allylic amines [19,21].…”
Section: Introductionmentioning
confidence: 99%
“…Para substituents are characterized which have influence on the catalyst activity, molecular weights and extent of branching of polymer. The presence of methyl group instead of hydrogen can cause decreasing in activities and the average molecular weights of polymers . Absence of the substituents in one side of MNC 4 , which has less electronic and steric effects around the metal center, can cause decreasing in activity ( E ).…”
Section: Resultsmentioning
confidence: 99%