C–F activation of perfluorophenazine at nickel: selectivity and mechanistic investigations

Torres, Òscar; Pfister, Nils; Braun, Thomas; Wittwer, Philipp

doi:10.1039/c9dt00780f

Cited by 4 publications

(2 citation statements)

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“…Multiplicity as well as the chemical shift result from intramolecular hydrogen bonds from the NH protons of the indolyl‐substituted phosphine toward the metal‐bound fluorido ligand. The signal is significantly shifted downfield when compared to data for other nickel(II) fluorido complexes with chemical shifts for the fluorido ligand of −360 to −411 ppm [30,32–34,40,41,54–63] . The 19 F{ 1 H}‐NMR spectrum of 1 shows four multiplet s at δ=−175.2, −149.4, −130.0 and −87.2 ppm corresponding to the four fluorine atoms of the aromatic pyridyl ligand.…”

Section: Resultsmentioning

confidence: 82%

“…The 31 P{ 1 H}‐NMR spectrum in (D 8 )toluene reveals a doublet at δ = −1.5 ppm. The 2 J (P,F) coupling constant of 35 Hz is characteristic for a coupling between the phosphorus nuclei and the metal‐bound fluorido ligand in a cis ‐position [30,33,34,40,41,54–58] . The metal‐bound fluorido ligand of complex 1 exhibits a triplet in the 19 F{ 1 H}‐NMR spectrum and a pseudo‐quintet in the 19 F‐NMR spectrum at δ=−336.2 ppm ( 2 J (P,F)=35 Hz, 1 J (NH⋅⋅⋅F)=38 Hz determined from 1 H‐NMR spectrum; Figure 1, inset).…”

Section: Resultsmentioning

confidence: 99%

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Indolyl Phosphine Nickel(II) Fluorido Complexes: Synthesis and Intermediates in Suzuki–Miyaura Cross‐Coupling Reactions

Braun‐Cula

Braun

2023

Helvetica Chimica Acta

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The CÀ F bond activation of pentafluoropyridine and 2, 3,5, 2 ] (cod = 1,5cyclooctadiene) in the presence of the phosphine PPh 2 (Ind) (Ind = 3-methyl-2-indolyl) led to the formation of the nickel(II) fluorido bis(phosphine) complexes trans-[Ni(F)(2-C 5 NF 4 ){PPh 2 (Ind)} 2 ] and trans-[Ni(F)(2-C 5 HNF 3 )-{PPh 2 (Ind)} 2 ]. The complexes are characterized by the presence of intramolecular hydrogen bonds between the NH group of the phosphine ligands and the fluorido ligand. Stochiometric model reactions of nickel(II) fluorido complexes with PhB(OH) 2 revealed that the former can be considered as intermediates in Suzuki-Miyaura cross coupling reactions. Catalytic experiments were attempted using 10 mol-% of trans-[Ni(F)(2-C 5 NF 4 ){PPh 2 (Ind)} 2 ] as catalyst and the activities of the PPh 2 (Ind) complex were compared to the ones of an analogous nickel(II) fluorido complex, bearing PPh 3 instead of PPh 2 (Ind) as ligands. The latter exhibited a somewhat lower catalytic activity suggesting a slight influence of the H-bonds in the outer coordination sphere.

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Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Indolyl Phosphine Nickel(II) Fluorido Complexes: Synthesis and Intermediates in Suzuki–Miyaura Cross‐Coupling Reactions

Braun‐Cula

Braun

2023

Helvetica Chimica Acta

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Experimental and Computational Studies towards Chemoselective C−F over C−Cl Functionalisation: Reversible Oxidative Addition is the Key

Jacobs

Keaveney

2020

ChemCatChem

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Catalytic cross‐coupling is a valuable tool for forming new carbon‐carbon and carbon‐heteroatom bonds, allowing access to a variety of structurally diverse compounds. However, for this methodology to reach its full potential, precise control over all competing cross‐coupling sites in poly‐functionalised building blocks is required. Carbon‐fluorine bonds are one of the most stable bonds in organic chemistry, with oxidative addition at C−F being much more difficult than at other C‐halide bonds. As such, the development of methods to chemoselectively functionalise the C−F position in poly‐halogenated arenes would be very challenging if selectivity was to be induced at the oxidative addition step. However, metal‐halide complexes exhibit different trends in reactivity to the parent haloarenes, with metal‐fluoride complexes known to be very reactive towards transmetalation. In this current work we sought to exploit the divergent reactivity of Ni−Cl and Ni−F intermediates to develop a chemoselective C−F functionalisation protocol, where selectivity is controlled by the transmetalation step. Our experimental studies highlight that such an approach is feasible, with a number of nickel catalysts shown to facilitate Hiyama cross‐coupling of 1‐fluoronapthalene under base free conditions, while no cross‐coupling with 1‐chloronapthalene occurred. Computational and experimental studies revealed the importance of reversible C−Cl oxidative addition for the development of selective C−F functionalisation, with ligand effects on the potential for reversibility also presented.

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Nickel-Carbon σ-Bonded Complexes

Wagner

Diao

2022

Comprehensive Organometallic Chemistry IV

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C–F activation of perfluorophenazine at nickel: selectivity and mechanistic investigations

Abstract: The reactivity of Ni(cod)2 in the presence of trialkylphosphines towards perfluorophenazine was investigated. Studies on the mechanism of the C–F activation process are reported.

Cited by 4 publications

References 73 publications

Indolyl Phosphine Nickel(II) Fluorido Complexes: Synthesis and Intermediates in Suzuki–Miyaura Cross‐Coupling Reactions

Indolyl Phosphine Nickel(II) Fluorido Complexes: Synthesis and Intermediates in Suzuki–Miyaura Cross‐Coupling Reactions

Experimental and Computational Studies towards Chemoselective C−F over C−Cl Functionalisation: Reversible Oxidative Addition is the Key

Nickel-Carbon σ-Bonded Complexes

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