Ethylene polymerization catalyzed by substituted pyrazole nickel complexes

Nelana, Simphiwe M.; Darkwa, James; Guzei, Ilia A.; Mapolie, Selwyn F.

doi:10.1016/j.jorganchem.2004.03.005

Cited by 41 publications

(23 citation statements)

References 26 publications

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“…Similar trends were also observed for others phosphinoyl-coordinated nickel complexes already described in the literature. The Ni(1)-N(2) bond distance [2.1841(12) Å] is close to the values previously reported for Ni (II) complexes containing pyrazolyl ligands, [8,13,[31][32][33][34] and the average Ni(1)-O(1) bond distance [2.0437(9) Å] is similar to that previously reported for others nickel-phosphinoyl complexes. The molecular structure of Ni1 is shown in Figure 3 and the main crystallographic data and structure refinement parameters are reported in Table 1.…”

Section: Synthesis and Characterization Of The Ni (Ii) Complexessupporting

confidence: 88%

Pyrazolyl‐phosphinoyl nickel (II) complexes: synthesis, characterization and ethylene dimerization studies

Junges

Dresch

Costa

et al. 2019

Applied Organom Chemis

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A series of new nickel (II) complexes of general formula [NiBr 2 (N,O) 2 ] (Ni1-Ni5) based on bidentate pyrazolyl-phosphinoyl ligands were prepared and characterized by IR spectroscopy, elemental analysis, high-resolution mass spectrometry (HRMS), and X-ray crystallography for Ni1. X-ray crystallographic analyses of Ni1 revealed a six-coordinate species, in which Ni (II) lies in an octaedral environment. The nickel center is chelated by two pyrazolyl-phosphinoyl ligands with the two bromide ligands occupying mutually trans positions. Upon activation with methylaluminoxane (MAO), all nickel complexes were able to oligomerize ethylene with turnover frequencies (TOFs) varying from 5.0 to 16.6 × 10 3 (mol ethylene) (mol Ni) −1 h −1 producing selectively 1-butene (91.0-95.5 wt%). The substitution on the pyrazolyl group and the length of the backbone chain play a significant role in the catalytic activity. The use of MAO/TMA (1:1) or MAO/TiBA (1:1) instead of MAO drastically reduced the activities. The TMA content has no significant influence on the selectivity. However, the use of TiBA leads to a reduction of 1-butene (from 94.9 to 71.0 wt%) and an improvement in the hexene production (from 1.5 to 23.3 wt%). Under optimized reaction conditions (10°C, 20 min, 20 bar ethylene, [Al/Ni] = 600), Ni1/MAO catalytic system yielded TOF = 24.7 × 10 3 (mol ethylene) (mol Ni) −1 h −1 with good selectivities for α-C4 (94.9 wt%).

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Section: Synthesis and Characterization Of The Ni (Ii) Complexessupporting

confidence: 88%

Pyrazolyl‐phosphinoyl nickel (II) complexes: synthesis, characterization and ethylene dimerization studies

Junges

Dresch

Costa

et al. 2019

Applied Organom Chemis

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“…The produced polyethylene contains low to moderate degree of branches. In contrast, Pd and Ni complexes with pyrazole ligands (5c) in combination with MAO afford linear polyethylene due to very rapid ethylene insertion [95,96]. It is noteworthy because most of the other cationic Pd complexes afford branched polyethylene.…”

Section: Cationic Complexes With Monodentate and Tridentate Ligandsmentioning

confidence: 99%

Olefin Polymerization with Non-metallocene Catalysts (Late Transition Metals)

Takeuchi

2014

Organometallic Reactions and Polymerization

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Diimine Pd and Ni complexes catalyze the polymerization of ethylene, propylene, and a-olefins. The reaction involves isomerization of the growing terminal (chain walking) and, as its result, produces highly branched polyethylene and poy(a-olefin)s having a smaller number of the alkyl substituents than expected from the monomer structure. Ni complexes with salicylaldimine or iminocarboxamide ligands and Pd complexes with phosphinesulfonate ligands are used as single component catalysts for ethylene polymerization. Especially, the latter catalysts show tolerance towards polar functional groups and promote copolymerization of ethylene with wide varieties of polar monomers. The Pd and Ni complexes are able to catalyze ethylene polymerization in aqueous media to yield polyethylene particles. Fe and Co complexes with bis(imino)pyridine ligands show high catalytic activity for ethylene polymerization to yield linear polyethylene. Complexes of the metals such as Rh, Ir, Ru, and Ag were revealed to become catalytically active by proper design of the ligand. Not only monometallic complexes but also bimetallic or multimetallic complexes are used for ethylene polymerization. Late transition metal complexes catalyze selective cyclopolymerization of non-conjugated dienes and trienes to afford the polymers with cycloalkane groups with controlled stereochemistry.

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“…Two related Ni II complexes have previously been characterized by X-ray crystallography, namely dibromotetrapyrazolenickel(II) [(Py) 4 NiBr 2 ; Mighell et al, 1969] and dibromotetra(3-methylpyrazole)nickel(II) [(Py3Me) 4 NiBr 2 ; Nelana et al, 2004]. Both compounds have the same connectivity and similar bond lengths, but some notable differences exist.…”

Section: Commentmentioning

confidence: 99%

trans-Dibromotetra(3-tert-butylpyrazole-κN)nickel(II)

2005

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Key indicatorsSingle-crystal X-ray study T = 223 K Mean (C-C) = 0.005 Å Disorder in main residue R factor = 0.045 wR factor = 0.125 Data-to-parameter ratio = 18.6For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2005 International Union of Crystallography Printed in Great Britain -all rights reservedThe title compound, [NiBr 2 (C 7 H 12 N 2 ) 4 ], is an octahedral Ni II complex coordinated by four pyrazolyl rings and two Br À anions. In the crystal structure, there are two independent Ni complexes, each with inversion symmetry. The tert-butyl groups of the ligands show orientational disorder.

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Ethylene polymerization catalyzed by substituted pyrazole nickel complexes

Cited by 41 publications

References 26 publications

Pyrazolyl‐phosphinoyl nickel (II) complexes: synthesis, characterization and ethylene dimerization studies

Pyrazolyl‐phosphinoyl nickel (II) complexes: synthesis, characterization and ethylene dimerization studies

Olefin Polymerization with Non-metallocene Catalysts (Late Transition Metals)

trans-Dibromotetra(3-tert-butylpyrazole-κN)nickel(II)

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