A Proton Directly Attacks 1,5-Cyclooctadiene in Bis(1,5-cyclooctadiene)nickel(0) in the Formation of a Keim Type Oligomerization Catalyst

Martin, Jeff; Nyström, Jan-Erik; Strömberg, Staffan; Svensson, Mats; Zetterberg, Krister; Zuber, M.

doi:10.1021/om971119s

Cited by 17 publications

(13 citation statements)

References 43 publications

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“…This property of nickel is taken advantage of industrially in the Shell higher olefin process, which has a capacity to convert 10 6 tons/year (1990) of ethylene to statistical mixtures of linear medium‐length terminal olefins. Such a polymerization catalyst was prepared by the reaction of (COD) 2 Ni with hexafluoroacetylacetone 41. Recently, Brookhart et al4–8 obtained excellent results by using nickel diimine derivatives activated by MAO.…”

Section: Resultsmentioning

confidence: 99%

Glyceryl‐S‐Acyl Carrier Protein as an Intermediate in the Biosynthesis of Tetronate Antibiotics

Sun¹,

Hong²,

Gillies³

et al. 2007

ChemBioChem

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The biosynthetic pathway to the unusual tetronate ring of certain polyketide natural products, including the antibiotics abyssomicin and tetronomycin (TMN) and the antitumour compound chlorothricin (CHL), is presently unknown. The gene clusters governing chlorothricin and tetronomycin biosynthesis both contain a gene encoding an atypical member of the FkbH family of enzymes, which has previously been shown to synthesise glyceryl-S-acyl carrier protein (ACP) as the first step in production of unusual extender units for modular polyketide biosynthesis. We show here that purified recombinant FkbH-like protein, Tmn16, from the TMN gene cluster catalyses the efficient transfer of a glyceryl moiety from D-1,3-bisphosphoglycerate (1,3-BPG) to either of the dedicated ACPs, Tmn7a and ChlD2, to form glyceryl-S-ACP, which directly implicates this compound as an intermediate in tetronate biosynthesis as well. Neither Tmn16 nor Tmn7a produced glyceryl-S-ACP when incubated, respectively, with analogous ACP and FkbH-like proteins from a known extender-unit pathway; this indicates a highly selective channelling of glycolytic metabolites into tetronate biosynthesis.

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Section: Resultsmentioning

confidence: 99%

Glyceryl‐S‐Acyl Carrier Protein as an Intermediate in the Biosynthesis of Tetronate Antibiotics

Sun¹,

Hong²,

Gillies³

et al. 2007

ChemBioChem

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“…Keim and Peuckert47 showed that Ni(COD) 2 undergoes reaction with Ph 2 PCH 2 CO 2 H, to yield the active ethylene oligomerization catalyst [P,O]Ni(η 3 ‐C 8 H 13 ). Indeed, in the presence of other bidentate ligands with acidic hydrogen atoms, such as hexafluoroacetylacetone, Ni(COD) 2 is also active for ethylene oligomerization 48. Based on deuterium labeling experiments, it was shown that the formation of the active catalyst occurs by direct protonation of an electron‐rich Ni‐coordinated alkene.…”

Section: Discussionmentioning

confidence: 99%

Ligand Steric and Fluoroalkyl Substituent Effects on Enchainment Cooperativity and Stability in Bimetallic Nickel(II) Polymerization Catalysts

Weberski

Chen

Delferro

et al. 2012

Chemistry A European J

114

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The synthesis and characterization of two neutrally charged bimetallic Ni(II) ethylene polymerization catalysts, {2,7-di-[2,6-(3,5-di-methylphenylimino)methyl]1,8-naphthalenediolato}-bis-Ni(II) (methyl)(trimethylphosphine) [(CH(3) )FI(2) -Ni(2) ] and {2,7-di-[2,6-(3,5-di-trifluoromethyl-phenylimino)methyl]-1,8-naphthalenediolato}-bis-Ni(II) (methyl)(trimethyl-phosphine) [(CF(3) )FI(2) -Ni(2) )], are reported. The diffraction-derived molecular structure of (CF(3) )FI(2) -Ni(2) reveals a Ni⋅⋅⋅Ni distance of 5.8024(5) Å. In the presence of ethylene and Ni(COD)(2) or B(C(6) F(5) )(3) co-catalysts, these complexes along with their monometallic analogues [2-tert-butyl-6-((2,6-(3,5-dimethylphenyl)phenylimino)methyl)-phenolate]-Ni(II) -methyl(trimethylphosphine) [(CH(3) )FI-Ni] and [2-tert-butyl-6-((2,6-(3,5-ditrifluoromethyl-phenyl)phenylimino)methyl)phenolato]-Ni(II) -methyl-(trimethylphosphine) [(CF(3) )FI-Ni], produce polyethylenes ranging from highly branched M(w) =1400 oligomers (91 methyl branches per 1000 C) to low branch density M(w) =92 000 polyethylenes (7 methyl branches per 1000 C). In the bimetallic catalysts, Ni⋅⋅⋅Ni cooperative effects are evidenced by increased product polyethylene branching in ethylene homopolymerizations (∼3× for (CF(3) )FI(2) -Ni(2) vs. monometallic (CF(3) )FI-Ni), as well as by enhanced norbornene co-monomer incorporation selectivity, with bimetallic (CH(3) )FI(2) -Ni(2) and (CF(3) )FI(2) -Ni(2) enchaining approximately three- and six-times more norbornene, respectively, than monometallic (CH(3) )FI-Ni and (CF(3) )FI-Ni. Additionally, (CH(3) )FI(2) -Ni(2) and (CF(3) )FI(2) -Ni(2) exhibit significantly enhanced thermal stability versus the less sterically encumbered dinickel catalyst {2,7-di-[(2,6-diisopropylphenyl)imino]-1,8-naphthalenediolato}-bis-Ni(II) (methyl)(trimethylphosphine). The pathway for bimetallic catalyst thermal deactivation is shown to involve an unexpected polymerization-active intermediate, {2,7-di-[2,6-(3,5-di-trifluoromethyl-phenylimino)methyl]-1-hydroxy,8-naphthalenediolato-Ni(II) (methyl)-(trimethylphosphine).

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“…They can behave as spectator ligands as in organonickel( II ) complexes which contain three‐electron‐donor anionic P,O chelates such as [Ph 2 PCH 2 C(O)O] − or [Ph 2 PCH−…︁C(−…︁O)Ph] − and which are efficient catalyst precursors for the highly selective oligomerization of ethylene into linear α ‐olefins, a reaction which forms the basis of the industrial Shell Higher Olefin Process (SHOP) 95–102. However, the postulated mechanism of this catalytic reaction does not imply hemilabile behavior of the P,O chelate but instead involves a hydrido nickel species of the type NiH(P,O) which is electronicaly unsaturated and allows the coordination and subsequent insertion of ethylene 96, 97, 103. In palladium( II ) chemistry such anionic P,O chelates may also behave as reactive moieties towards a wide range of electrophilic organic or inorganic reagents.…”

Section: Hemilabile Ligandsmentioning

confidence: 99%

Hemilability of Hybrid Ligands and the Coordination Chemistry of Oxazoline-Based Systems

Braunstein

Naud

2001

Angew. Chem. Int. Ed.

943

618

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Ligand design is becoming an increasingly important part of the synthetic activity in chemistry. This is of course because of the subtle control that ligands exert on the metal center to which they are coordinated. Ligands which contain significantly different chemical functionalities, such as hard and soft donors, are often called hybrid ligands and find increasing use in molecular chemistry. Although the interplay between electronic and steric properties has long been recognized as essential in determining the chemical or physical properties of a complex, predictions remain very difficult, not only because of the considerable diversity encountered within the Periodic Table—different metal centers will behave differently towards the same ligand and different ligands can completely modify the chemistry of a given metal—but also because of the small energy differences involved. New systems may—even through serendipity—allow the emergence of useful concepts that can gain general acceptance and help design molecular structures orientated towards a given property. The concept of ligand hemilability, which finds numerous illustrations with hybrid ligands, has gained increased acceptance and been found to be very useful in explaining the properties of metal complexes and in designing new systems for molecular activation, homogeneous catalysis, functional materials, or small‐molecule sensing. In the field of homogeneous enantioselective catalysis, in which steric and/or electronic control of a metal‐mediated process must occur in such a way that one stereoisomer is preferentially formed, ligands containing one or more chiral oxazoline units have been found to be very valuable for a wide range of metal‐catalyzed reactions. The incorporation of oxazoline moieties in multifunctional ligands of increasing complexity makes such ligands good candidates to display hemilabile properties, which until recently, had not been documented in oxazoline chemistry. Herein, we briefly recall the definition and scope of hemilabile ligands, present the main classes of ligands containing one or more oxazoline moieties, with an emphasis on hybrid ligands, and finally explain why the combination of these two facets of ligand design appears particularly promising.

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A Proton Directly Attacks 1,5-Cyclooctadiene in Bis(1,5-cyclooctadiene)nickel(0) in the Formation of a Keim Type Oligomerization Catalyst

Cited by 17 publications

References 43 publications

Glyceryl‐S‐Acyl Carrier Protein as an Intermediate in the Biosynthesis of Tetronate Antibiotics

Glyceryl‐S‐Acyl Carrier Protein as an Intermediate in the Biosynthesis of Tetronate Antibiotics

Ligand Steric and Fluoroalkyl Substituent Effects on Enchainment Cooperativity and Stability in Bimetallic Nickel(II) Polymerization Catalysts

Hemilability of Hybrid Ligands and the Coordination Chemistry of Oxazoline-Based Systems

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