- Facile Route to Silver Triarene Borate Salts, [Ag(arene)3][B(C6F5)4]: Thermodynamics, Structure, and Bonding
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A facile synthesis and full characterization of a series of [Ag(arene)3][B(C6F5)4] salts (arene = C6H6, MeC6H5, EtC6H5, i-PrC6H5
- Ibad, Muhammad Farooq,Schulz, Axel,Villinger, Alexander
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- Pentafluorophenyl Silver: Structure and Bonding of Arene Solvates
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The synthesis and full characterization of a series of AgC6F5·arene complexes (arene = RC6H5 with R = Me, Et; R2C6H4, R3C6H3, R4C6H2, and R5C6H with R = Me) are presented. The structure and bonding are discussed on the basis of X-ray and theoretical studies with respect to the substitution pattern at the arene. Additionally, the structure of neat AgC6F5 and a facile way to generate crystals of pure AgC6F5 are reported. (Figure Presented).
- Ibad, Muhammad Farooq,Schulz, Axel,Villinger, Alexander
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- Ranking Ligands by Their Ability to Ease (C6F5)2NiIIL → Ni0L + (C6F5)2Coupling versus Hydrolysis: Outstanding Activity of PEWO Ligands
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The NiII literature complex cis-[Ni(C6F5)2(THF)2] is a synthon of cis-Ni(C6F5)2 that allows us to establish a protocol to measure and compare the ligand effect on the NiII → Ni0 reductive elimination step (coupling), often critical in catalytic processes. Several ligands of different types were submitted to this Ni-meter comparison: Bipyridines, chelating diphosphines, monodentate phosphines, PR2(biaryl) phosphines, and PEWO ligands (phosphines with one potentially chelate electron-withdrawing olefin). Extremely different C6F5-C6F5 coupling rates, ranging from totally inactive (producing stable complexes at room temperature) to those inducing almost instantaneous coupling at 25 °C, were found for the different ligands tested. The PR2(biaryl) ligands, very efficient for coupling in Pd, are slow and inefficient in Ni, and the reason for this difference is examined. In contrast, PEWO type ligands are amazingly efficient and provide the lowest coupling barriers ever observed for NiII complexes; they yield up to 96% C6F5-C6F5 coupling in 5 min at 25 °C (the rest is C6F5H) and 100% coupling with no hydrolysis in 8 h at-22 to-53 °C.
- Ponce-De-León, Jaime,Gioria, Estefania,Martínez-Ilarduya, Jesús M.,Espinet, Pablo
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supporting information
p. 18287 - 18294
(2020/12/23)
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- Cooperative Au/Ag Dual-Catalyzed Cross-Dehydrogenative Biaryl Coupling: Reaction Development and Mechanistic Insight
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An operationally simple and highly selective Au/Ag bimetallic-catalyzed cross-dehydrogenative biaryl coupling between pyrazoles and fluoroarenes has been developed. With this reaction, a wide range of biheteroaryl products can be obtained in moderate to good yields with excellent functional group compatibility. The exact role of silver salts, previously overlooked in most gold-catalyzed transformations, has been carefully investigated in this biaryl coupling. Insightful experimental and theoretical studies indicate that silver acetate is the actual catalyst for C-H activation of electron-poor arenes, rather than the previously reported gold(I)-catalyzed process. An unprecedented Au/Ag dual catalysis is proposed, in which silver(I) is responsible for the activation of electron-poor fluoroarenes via a concerted metalation-deprotonation pathway, and gold(III) is responsible for the activation of electron-rich pyrazoles via an electrophilic aromatic substitution process. Kinetic studies reveal that ArFnAu(III)-mediated C-H activation of pyrazoles is most likely the rate-limiting step.
- Li, Weipeng,Yuan, Dandan,Wang, Guoqiang,Zhao, Yue,Xie, Jin,Li, Shuhua,Zhu, Chengjian
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supporting information
p. 3187 - 3197
(2019/02/19)
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- Catalysis with Pnictogen, Chalcogen, and Halogen Bonds
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Halogen- and chalcogen-based σ-hole interactions have recently received increased interest in non-covalent organocatalysis. However, the closely related pnictogen bonds have been neglected. In this study, we introduce conceptually simple, neutral, and mon
- Benz, Sebastian,Poblador-Bahamonde, Amalia I.,Low-Ders, Nicolas,Matile, Stefan
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supporting information
p. 5408 - 5412
(2018/03/23)
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- Role of silver salts in palladium-catalyzed arene and heteroarene C-H functionalization reactions
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Silver carboxylate salts are widely used as additives in palladium-catalyzed C-H functionalization reactions. However, the role of these silver additives is often not fully understood. This paper describes an investigation of the role of AgOPiv in the stoichiometric activation of C6F5H at a well-defined PdII complex as well as in the PdII-catalyzed oxidative dimerization of 2-alkylthiophenes. Both in situ NMR spectroscopy and H/D exchange studies of the reactions of C6F5H implicate a role for AgOPiv in the C-H cleavage event, generating Ag-C6F5 as an intermediate. The catalytic studies show similar trends despite the different conditions and substrates, suggesting that AgOPiv promotes a similar metalation of the thiophene in the catalytic transformations. This proposal is supported by DFT calculations, which show energetically feasible pathways for concerted metalation-deprotonation of both 2-methylthiophene and pentafluorobenzene at [Ag(OPiv)]2. These studies suggest that initial metalation of C-H substrates at AgI carboxylates should be considered as a plausible pathway in C-H functionalization reactions involving mixtures of Ag and Pd salts.
- Lotz, Monica D.,Camasso, Nicole M.,Canty, Allan J.,Sanford, Melanie S.
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supporting information
p. 165 - 171
(2017/11/27)
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- Approaches to prepare perfluoroalkyl and pentafluorophenyl copper couples for cross-coupling reactions with organohalogen compounds
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The reactions of iodoperfluoroalkanes CnF2n+1I (n = 2, 3, 4) and n-BuLi at low temperatures give NMR spectroscopic evidence for LiCnF2n+1 which were converted into LiCu(CnF2n+1)2 derivatives upon treatment with 0.5 mol copper(i) bromide, CuBr. An alternative route to obtain perfluoroorgano copper couples, Cu(Rf)2Ag (Rf = n-C3F7, n-C4F9, C6F5) was achieved from the reactions of the corresponding perfluoroorgano silver(i) reagents, AgRf, and elemental copper through redox transmetallations. The composition of the resulting reactive intermediates was investigated by means of 19F NMR spectroscopy and ESI mass spectrometry. Perfluoro-n-propyl and perfluoro-n-butyl copper-silver reagents prepared by the oxidative transmetallation route exhibited good properties in C-C bond formation reactions with acid chlorides even under moderate conditions. Substitution of bromine directly bound to aromatics for perfluoroalkyl groups was achieved at elevated temperatures, while success in halide substitution reactions using lithium copper couples remained poor.
- Kremlev, Mikhail M.,Mushta, Aleksej I.,Tyrra, Wieland,Yagupolskii, Yurii L.,Naumann, Dieter,Sch?fer, Mathias
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p. 19693 - 19699
(2015/11/27)
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- Silver compounds in synthetic chemistry. 1. A facile preparative route for pentafluorophenylsilver, AgC6F5 and its use as an oxidative pentafluorophenyl group transfer reagent in reactions with group 12 to 16 elements
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AgC6F5 is directly and quantitatively formed from room temperature reactions of AgF and Me3SiC6F5 in N-donor solvents, particularly EtCN. Solutions of AgC6F5 prepared by this method exhibit excellent oxidative properties in reactions with a variety of groups 12 to 16 elements giving the corresponding pentafluorophenyl element compounds in moderate to excellent yields. AgC6F5·EtCN crystallises with monoclinic symmetry (C2/c, Z = 8, a = 2301.4(5)pm, b = 1078.8(4)pm, c = 948.0(2)pm, β = 113.19(1)°) and exhibits chains of silver atoms with bridging C6F5 groups.
- Tyrra, Wieland,Wickleder, Mathias S.
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p. 1841 - 1847
(2008/10/08)
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- Synthesis of Pentafluorophenyl(ylide)silver(I) Complexes: X-Ray Structures of two Modifications of
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Monomeric silver ylide complexes (ER3=PPh3, PPh2Me, PPhMe2, or AsPh3) can be prepared by the reaction of Ag(CF3CO2) with Li(C6F5) and .The free ylides CH2PPh3, CH2PPh2Me, or CH(CO2Me)PPh3 react with Ag(C6F5) or AgClO4 to afford or ClO4 respectively.Several novel ylide-transfer reactions from silver ylides to other silver or gold centres are reported.The structures of two forms of have been established.The molecules differ mainly in the orientation of one phenyl ring.The C6F5 groups are highly distorted at the ipso carbon .
- Uson, Rafael,Laguna, Antonio,Uson, Alfredo,Jones, Peter G.,Meyer-Baese, Karen
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p. 341 - 346
(2007/10/02)
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- Synthesis of (η6-arene)NIR2 and CoR2 (R = σ-bound halosilanes and haloarenes) by (allyl)2Ni/HR reactions and combined metal trifluoroacetate/grignard reagent methods
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Conventional solution methods, rather than metal atom/vapor methods, have been devised for synthesis of (η6-arene)MR2, where M = Co and Ni and R = SiF3, SiCl3, SiCl2Me, C6F5, C6F4H, and C6Cl5. The halosilane derivatives as well as polymeric Ni(SC6F5)2 and Ni(OC6F5)2 were prepared by reaction of HSiF3, HSiCl3, HSiCl2Me, HOC6F5, and HSC6F5 with (2-methylallyl)2Ni in arene solvents. A different approach was necessary for the R = haloaryl derivatives. Such a sequence involved preparation of (CF3CO2)2Ni from CF3COOAg followed by reaction with C6Cl5Li to form (C6Cl5)2Ni etherate which was converted to (C6Cl5)2Ni(η6-arene) by reaction with an arene/BF3 mixture (although simply heating with the arene worked with some systems). This method allowed more convenient syntheses of known (η6-arene)MR2 complexes and, for the first time, synthesis of the C6F4H and C6Cl5 derivatives.
- Lin, Shaw-Tao,Narske, Richard N.,Klabunde, Kenneth J.
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p. 571 - 574
(2008/10/08)
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- PENTAHALOPHENYLARGENTATE(I) COMPLEXES
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The reaction of (CF3COO)Ag with LiR gives (R = C6F5 or C6Cl5).The latter react with acids HX to give organoargentate(I) derivatives of the types (X = CH3COO, CF3COO or 8-oxyquinolate) or 22BiBzIm> (BiBzIm = bibenzimidazolate), whilst the reaction with silver salts AgX yields 2X> (X = NO3 or CF3COO) or AgR (X = ClO4).
- Uson, R.,Laguna, A.,Abad, J. A.
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p. 341 - 345
(2007/10/02)
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