Remote Substituents Controlling Catalytic Polymerization by Very Active and Robust Neutral Nickel(<scp>II</scp>) Complexes

Zuideveld, Martin A.; Wehrmann, Peter; Röhr, Caroline; Mecking, Stefan

doi:10.1002/ange.200352062

Cited by 56 publications

(51 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[22] For example, whereas for R = CF 3 high molecular weight, nearly linear semicrystalline polyethylene is obtained (M w = 10 5 g mol À1 ; 10 branches per 1000 C atoms), a catalyst precursor with R = CH 3 affords highly branched, entirely amorphous low molecular-weight polymer (M w = 2.3 10 3 g mol À1 ; 76 branches per 1000 C atoms).…”

Section: Resultsmentioning

confidence: 99%

“…Perfluorinated octyl groups (R F = C 8 F 17 ) were introduced by copper-catalysed coupling, affording the aryl bromide 1. [24] In analogy to the synthesis of the aforementioned terphenyl-substituted salicylaldimines, [22,25] transformation of bromide 1 into a boronic acid (2) followed by Suzuki coupling afforded aniline 3, which bears para-R Fsubstituted aryl groups in the 2,6-positions. Condensation of 3 with 3,5-diiodosalicylaldehyde yielded salicylaldimine 5 a in 70 % yield (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

“…Effect of remote substituents in ethylene polymerisation (*: monosubstitution only of the aryl groups for NO 2 ). [22] Scheme 2. Synthesis of perfluorinated salicylaldimine 5 a.…”

Section: Resultsmentioning

confidence: 99%

“…The nickel-bound methyl group and the O donor atom are arranged in a trans position, as previously found for similar nickel-salicylaldiminato complexes (Scheme 4). [22,32] It has been documented that nickel complexes can react with CO 2 , which would result in catalyst deactivation. [33] For example, insertion of carbon dioxide into a Ni-ethyl bond of [Ni(Et) 2 A C H T U N G T R E N N U N G (bipy)], to afford diethylketone and the nickel pro-…”

Section: Resultsmentioning

confidence: 99%

“…Thus, ethylene homopolymerisation affords polyethylenes ranging from semicrystalline, nearly linear to amorphous, highly branched. [22] The unique combination of versatility and functional group tolerance prompted us to study polymerisation in CO 2 as a reaction medium with these complexes. Nickel(II) complexes with perfluoroalkylsubstituted salicylaldimine ligands, which render them "CO 2 -philic", [23] were prepared for this purpose.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Catalytic Ethylene Polymerisation in Carbon Dioxide as a Reaction Medium with Soluble Nickel(II) Catalysts

Bastero¹,

Franciò²,

Leitner³

et al. 2006

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

A series of neutral NiII–salicylaldiminato complexes substituted with perfluorooctyl‐ and trifluoromethyl groups, [Ni{κ2‐N,O‐6‐C(H)NAr‐2,4‐R′2C6H2O}(Me)(pyridine)] (6 a: Ar=2,6‐{4‐(F17C8)C6H4}2C6H3, R′=I; 6 b: Ar=2,6‐{4‐(F3C)C6H4}2C6H3, R′=I; 6 c: Ar=2,6‐{3,5‐(F3C)2C6H3}2C6H3, R′=3,5‐(F3C)2C6H3; 6 d: Ar=2,6‐{4‐(F17C8)C6H4}2C6H3, R′=3,5‐(F3C)2C6H3; 6 e: Ar=2,6‐{3,5‐(F3C)2C6H3}2C6H3, R′=I) were studied as catalyst precursors for ethylene polymerisation in supercritical CO2. Catalyst precursors 6 a and 6 c, which are soluble in scCO2, afford the highest polymer yields, corresponding to 2×103 turnovers. Semicrystalline polyethylene (Mn typically 104 g mol−1) is obtained with variable degrees of branching (11 to 24 branches per 1000 carbon atoms, predominantly Me branches) and crystallinities (54 to 21 %), depending on the substitution pattern of the catalyst.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Effect of remote substituents in ethylene polymerisation (*: monosubstitution only of the aryl groups for NO 2 ). [22] Scheme 2. Synthesis of perfluorinated salicylaldimine 5 a.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Catalytic Ethylene Polymerisation in Carbon Dioxide as a Reaction Medium with Soluble Nickel(II) Catalysts

Bastero¹,

Franciò²,

Leitner³

et al. 2006

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

Aqueous Dispersions of Extraordinarily Small Polyethylene Nanoparticles

Kolb

Monteil

Thomann³

et al. 2004

Angewandte Chemie

View full text Add to dashboard Cite

General methods and materials. Ethylene of 3.5 grade was supplied by Praxair. Demineralised water was distilled under argon. 2-propanol (p.a.) was degassed by four repeated freeze-thaw cycles. Chloranil (Aldrich) und sodium dodecyl sulfate (Fluka) were used without further purification. Potassium 4-(diphenylphosphino)benzenesulfonate (TPPMS) was synthesized as described in [1]. bis (1,5-cyclooctadiene) nickel was synthesized according to [2] (the compound is also available commercially, e.g. at Aldrich or Strem). TEM investigations were carried out on a LEO 912 Omega apparatus using an acceleration voltage of 120 kV. Samples were stained with RuO 4 . For microtome cutting, the latex particles were embedded in nanoplast ® (a hydrophilic melamine resin). Microtome cuts of ca. 50 nm thickness were prepared with a Reichert & Jung Ultracut E microtome equipped with a 45° diamond knife supplied by Diatome. AFM experiments were performed with a Nanoscope III scanning probe microscope. The height and phase images were obtained simultaneously while operating the instrument in the tapping mode under ambient conditions. Images were taken at the fundamental resonance frequency of the Si cantilevers which was typically around 180 kHz. Typical scan speeds during recording were 0.3-1 line/s using scan heads with a maximum range of 16 × 16 µm. The phase images represent the variations of relative phase shifts (i. e. the phase angle of the interacting cantilever relative to the phase angle of the freely oscillating cantilever at the resonance frequency) and are thus able to distinguish materials by their material properties (e.g. amorphous and crystalline polymers). DSC was performed on a Perkin Elmer DSC 7 instrument or on a Pyris 1 DSC at a heating and cooling rate of 10 K min -1 . T m data reported are local maxima of the second heats. DSC traces of polymer dispersions were obtained on 20 to 30 mg of dispersion with ca. 5 % by weight polymer content. NMR spectra were recorded on a Bruker ARX 300 instrument (

show abstract

Mechanistische Untersuchungen des Kettenwachstums von Polyethylen in Gegenwart von Wasser

Berkefeld

Mecking

2006

Angewandte Chemie

Self Cite

View full text Add to dashboard Cite

General procedures and materialsAll experiments were carried out under argon of 99.998 % purity using standard Schlenk line techniques or in a glovebox under nitrogen. All glassware was dried carefully by treatment with a heat gun under high vacuum or in an oven at 90• C overnight. Solvents were dried and distilled under argon prior use. Ethers were dried over Na/ benzophenone, pentane and CH 2 Cl 2 over CaH 2 . to residual proton resonances of the solvents. In general, low temperature NMR experiments were carried out with prior temperature determination using a sample of neat methanol. 1D1 H spectra of α-diimine(dimethyl)palladium(II) were acquired at room temperature on a Bruker 250 spectrometer operating at 250 MHz. Synthetic ProceduresThe Synthesis of α-diimine(dimethyl)palladium(II)A 100 mL Schlenk flask was charged with 0.57 g (2 mmol) of [(cod)PdCl 2 ] and 0.11 g (2 mmol) of dimethyl magnesium in the glovebox. After cooling to -80• C, 40 mL of diethyl ether were added via canula. The resulting yellow suspension was stirred and allowed to warm to -30• C. After filtration and washing of the residual solid with diethyl ether at -10• C the resulting light brown solution was cooled again to -80• C. Afterwards, a solution of 0.81 g (2 mmol) of the diimine in 10 mL of diethyl ether was added via canula. After warming to room temperature overnight a brown solid precipitated. The suspension was chilled again to -30• C in order to complete precipitation. The resulting red brown solid was isolated and washed with a small amount of pentane. Finally, it was dissolved in 10 mL of methylene chloride. The solvent was reduced to approximately 2 to 3 mL and the deep red solution was layered with 20 mL of pentane. Crystallisation at room temperature yielded 0.52 g (0.96 mmol, 48%) of dark purple crystals.

show abstract

Remote Substituents Controlling Catalytic Polymerization by Very Active and Robust Neutral Nickel(II) Complexes

Cited by 56 publications

References 52 publications

Catalytic Ethylene Polymerisation in Carbon Dioxide as a Reaction Medium with Soluble Nickel(II) Catalysts

Catalytic Ethylene Polymerisation in Carbon Dioxide as a Reaction Medium with Soluble Nickel(II) Catalysts

Aqueous Dispersions of Extraordinarily Small Polyethylene Nanoparticles

Mechanistische Untersuchungen des Kettenwachstums von Polyethylen in Gegenwart von Wasser

Contact Info

Product

Resources

About