Bimetallic Effects for Enhanced Polar Comonomer Enchainment Selectivity in Catalytic Ethylene Polymerization

Rodriguez, Brandon; Delferro, Massimiliano; Marks, Tobin J.

doi:10.1021/ja900257k

Cited by 110 publications

(74 citation statements)

References 104 publications

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“…7,11,17–24 With systems a and b , ethylene polymerization activities are similar to mononuclear controls, but enhanced comonomer incorporation and activity occur in the copolymerization of ethylene with functionalized norbornene derivatives. 19,20 When activated with MAO, system e produces polymer with higher M w than some previously reported mononuclear systems.…”

Section: Introductionmentioning

confidence: 86%

“…7,11,17–24 In these systems, the two nickel centers are linked via either the imine donor ( a , b , e , f, g ), the phenoxide donor ( d , h ), or both ( c ). The measured or proposed Ni–Ni distance varies from 3.1 Å ( h ) to between 7.5–8.5 Å ( c , d , e , and f ).…”

Section: Introductionmentioning

confidence: 99%

“…The measured or proposed Ni–Ni distance varies from 3.1 Å ( h ) to between 7.5–8.5 Å ( c , d , e , and f ). 11,18,19,21–24 Analysis of the solid-state structures highlights the challenge in orienting the metal centers such that they would react cooperatively with substrates. For some of the reported systems the metals are found in geometries that make intramolecular cooperativity unlikely.…”

Section: Introductionmentioning

confidence: 99%

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Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

2012

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Dinuclear nickelphenoxyiminato olefin polymerization catalysts based on rigid p-terphenyl frameworks are reported. Permethylation of the central arene of the terphenyl unit and oxygen substitution of the peripheral rings ortho to the aryl-aryl linkages blocks rotation around these linkages allowing atropisomers of the ligand to be isolated. The corresponding syn and anti dinickel complexes (25-s and 25-a) were synthesized and characterized by single crystal X-ray diffraction. These frameworks limit the relative movement of the metal centers restricting the metal-metal distance. Kinetics studies of isomerization of a ligand precursor (7-a) allowed the calculation of the activation parameters for the isomerization process (ΔH‡ = 28.0 ± 0.4 kcal×mol−1 and ΔS‡ = −12.3 ± 0.4 cal×mol−1×K−1). The reported nickel complexes are active for ethylene polymerization [TOF up to 3700 (mol C2H4)×(mol Ni)−1×h−1] and ethylene/α-olefin copolymerization. Only methyl branches are observed in the polymerization of ethylene, while α-olefins are incorporated without apparent chain walking. These catalysts are active in the presence of polar additives and in neat tetrahydrofuran. The syn and anti isomers differ in polymerization activity and polymer degree of branching and molecular weight. For comparison, a series of mononuclear nickel complexes (26, 27-s, 27-a, 28, 30) was prepared and studied. The effects of structure and catalyst nuclearity on reactivity are discussed.

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Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

2012

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“…The group of Marks has made elegant contributions using welldesigned dinickel complexes based on dinucleating phenoxyiminato ligands, which were shown to induce cooperative catalysis in both the homopolymerization of ethylene and the copolymerization of ethylene with polar comonomers (norbornadiene and acrylates). [64] This has led to high levels of comonomer incorporation, significantly higher branch-content in PE and hence in different polymer microstructures. Meyer has developed innovative dinucleating ligands based on functionalized pyrazolate scaffolds and the corresponding Ni, Cu and Zn bimetallic complexes thereof, which are active models for urease (Ni), [65] phosphatase (Zn) [66] and e.g.…”

Section: Bimetallic Catalysismentioning

confidence: 99%

Cooperative Catalysis with First‐Row Late Transition Metals

2011

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Cooperative catalysis with first-row transition metals holds much promise for future developments regarding sustainable, selective transformations, including e.g. alkenes, dienes and a variety of small molecules such as CO 2 , N 2 and water. This non-exhaustive analysis of the current state-ofthe-art aims to give a comprehensive overview of the various design strategies and applications of first-row transition metal cooperative reactivity and to provide leads for new research initiatives in order to expand this emerging field. The

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“…Compounds encompassing a bimetallic core may demonstrate explicit reactivity patterns for the conversion of olefin monomers into oligomers/polymers, which arise from a subtle interplay between the metals and the ligands. Currently, there is great interest in both bridged and non-bridged bimetallic late-first-row transition-metal coordination catalysts for the oligomerization/polymerization of olefins with definite electronic and steric modulations [2][3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Ethylene Oligomerizations by Diazene Bridged Ni(II) Catalysts Derived from Pyrazole-Scaffold-Based Binucleating Ligands with Alkyl and Aryl Pendant Arms

et al. 2011

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The coordination and organometallic chemistry of a series of diazene (N 2 )-bridged Ni(II) catalysts derived from pyrazole-scaffold-based ligands bearing alkyl and aryl pendent arms was investigated. Binucleating ligands were obtained as products of the condensation reaction between 3,5-dichloroformyl-1H-pyrazole and aliphatic/ aromatic primary/secondary amines under anhydrous conditions. The Ni(II) catalysts were activated with ethyl aluminum sesquichloride (EASC) to oligomerize the ethylene mainly into C4, C6, C8, and C10 fractions with activities up to 1.2 and 0.5 9 10 6 g (mol-Ni) -1 bar -1 h -1 at 30 and 50°C, respectively. All catalysts were found to be electrochemically active in the working potential range of -2 to ?2 V. A change in the potential of Ni(II) was provoked by the N 4 donor bridging ligands, increasing the ethylene oligomerization activity.

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Bimetallic Effects for Enhanced Polar Comonomer Enchainment Selectivity in Catalytic Ethylene Polymerization

Cited by 110 publications

References 104 publications

Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

Cooperative Catalysis with First‐Row Late Transition Metals

Ethylene Oligomerizations by Diazene Bridged Ni(II) Catalysts Derived from Pyrazole-Scaffold-Based Binucleating Ligands with Alkyl and Aryl Pendant Arms

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