- Alkyne/alkene/allene-induced disproportionation of cationic gold(i) catalyst
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The first detailed experimental study of the deactivation of cationic gold was conducted, and the influence of each component in the reaction system (substrate, counterion, solvent) on the decay process was examined. It was found that a substrate (alkyne/allene/alkene)-induced disproportionation of gold(I) may play a key role in the decay process. Our mechanism is supported by kinetic, XPS, voltammetry studies, and high-resolution ESI-MS data. The first detailed experimental study of the deactivation of cationic gold was conducted, and the influence of each component in the reaction system (substrate, counterion, solvent) on the decay process was examined. It was found that a substrate (alkyne/allene/alkene)-induced disproportionation of gold(I) may play a key role in the decay process (see scheme; TFa=atrifluoromethanesulfonyl).
- Kumar, Manish,Jasinski, Jacek,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 3113 - 3119
(2014/03/21)
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- Coordination chemistry of gold catalysts in solution: A detailed NMR study
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Coordination chemistry of gold catalysts bearing eight different ligands [L=PPh3, JohnPhos (L2), Xphos (L3), DTBP, IMes, IPr, dppf, S-tolBINAP (L8)] has been studied by NMR spectroscopy in solution at room temperature. Cationic or neutral mononuclear complexes LAuX (L=L2, L3, IMes, IPr; X=charged or neutral ligand) underwent simple ligand exchange without giving any higher coordinate complexes. For L2AuX the following ligand strength series was determined: MeOHahex-3-yne -aMe 2S3CO2 -≈DMAP3-≈Cl -. Some heteroligand complexes DTBPAuX exist in solution in equilibrium with the corresponding symmetrical species. Binuclear complexes dppf(AuOTf)2 and S-tolBINAP(AuOTf)2 showed different behavior in exchange reactions with ligands depending on the ligand strength. Thus, PPh3 causes abstraction of one gold atom to give mononuclear complexes LLAuPPh3+ and (Ph3P) nAu+, but other N and S ligands give ordinary dicationic species LL(AuNu)22+. In reactions with different bases, LAu+ provided new oxonium ions whose chemistry was also studied: (DTBPAu)3O+, (L2Au)2OH+, (L2Au) 3O+, (L3Au)2OH+, and (IMesAu) 2OH+. Ultimately, formation of gold hydroxide LAuOH (L=L2, L3, IMes) was studied. Ligand- or base-assisted interconversions between (L2Au)2OH+, (L2Au)3O+, and L2AuOH are described. Reactions of dppf(AuOTf)2 and S-tolBINAP(AuOTf) 2 with bases provided more interesting oxonium ions, whose molecular composition was found to be [dppf(Au)2]3O2 2+, L8(Au)2OH+, and [L8(Au)2] 3O22+, but their exact structure was not established. Several reactions between different oxonium species were conducted to observe mixed heteroligand oxonium species. Reaction of L2AuNCMe+ with S2- was studied; several new complexes with sulfide are described. For many reversible reactions the corresponding equilibrium constants were determined. Copyright
- Zhdanko, Alexander,Stroebele, Markus,Maier, Martin E.
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p. 14732 - 14744
(2013/01/15)
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- Ligand effects and ligand design in homogeneous gold(I) catalysis
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Gold catalysis is considered one of the most important breakthroughs in organic synthesis during the past decade, but a rational understanding of ligand effects in gold catalysis is lacking. Most gold-catalyzed reactions go through three major stages: (i) electronic activation of alkyne (or allene) to generate a vinyl gold intermediate; (ii) protodeauration to generate the product and regenerate the cationic gold catalyst; (iii) decay of the active gold catalyst. Our research provides a clearer understanding of how ligands influence each of the three stages in the gold catalytic cycle. What is even more important, by not focusing on a particular gold-catalyzed reaction, we have been able to categorize most gold-catalyzed reactions and propose a ligand design protocol for each category of gold-catalyzed reactions.
- Wang, Weibo,Hammond, Gerald B.,Xu, Bo
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p. 5697 - 5705
(2012/06/04)
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- Tetrazolyl and tetrazolylidene complexes of gold: A synthetic and structural study
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Lithiation of 1-benzyl-1H-tetrazole followed by transmetallation with [AuCl(PPh3)], [Au(C6F5)(tht)] or [AuCl(tht)] (tht = tetrahydrothiophene) and subsequent alkylation afforded cationic 1-benzyl-4-methyl-4,5-dihydro-1H-1,2,3,4-tetrazol-5-ylidene(triphenylphosphine) gold(i), 1, neutral 1-benzyl-4-methyl-4,5-dihydro-1H-1,2,3,4-tetrazol-5- ylidene(pentafluorophenyl)gold(i), 2, and a cationic biscarbene complex, bis(1-benzyl-4-methyl-4,5-dihydro-1H-1,2,3,4-tetrazol-5-ylidene)gold(i), 3. The first complex underwent a homoleptic rearrangement in solution to form 3. Reaction of [Au(N3)PPh3] with the three isocyanides (CH3)2C6H3NC, tBuNC and CyNC, respectively, yielded the corresponding neutral tetrazolyl(phosphine) complexes of gold, [1-(2,6-dimethylphenyl)-1H-tetrazol-5-yl](triphenylphosphine) gold(i), 4, [1-(tert-butyl)-1H-tetrazol-5-yl](triphenylphosphine)gold(i), 6, and [1-(cyclohexyl)-1H-tetrazol-5-yl](triphenylphosphine)gold(i), 7. Alkylation of 4 with methyl triflate on N4 allowed isolation of the crystalline carbene complex 1-(2,6-dimethylphenyl)-4-methyl-4,5-dihydro-1H-1,2,3,4-tetrazol- 5-ylidene)(triphenylphosphine)gold(i), 5. Complex 7 was not isolable in pure form but converts by isocyanide substitution of triphenylphosphine into [1-cyclohexylisocyanide][1-(cyclohexyl)-1H-tetrazol-5-yl]gold(i), 8. From a product mixture of 7 and 8 the transformed molecules [(cyclohexylamino)(ethoxy) carbene](1-cyclohexyl-1H-tetrazol-5-yl)gold(i), 9, and [bis(cyclohexylamino) carbene](1-cyclohexyltetrazol-5-yl)gold(i), 10, co-crystallised spontaneously after a long time at -20 °C.
- Gabrielli, William F.,Nogai, Stefan D.,McKenzie, Jean M.,Cronje, Stephanie,Raubenheimer, Helgard G.
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p. 2208 - 2218
(2011/04/23)
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- Group 11 complexes with unsymmetrical P,S and P,Se disubstituted ferrocene ligands
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The reaction of the unsymmetrical ligands l-diphenylphosphino-1′-(phenylsulfanyl)ferrocene and 1-diphenylphosphino-1′-(phenylselenyl)ferrocene, Fc(EPh)PPh2 (E = S, Se), with several group 11 metal derivatives leads to the synthesis of complexes of the type [MX{Fc(EPh)PPh2}] (M = Au, X = Cl, C 6F5; M = Ag, X = OTf), (OTf = trifluoromethanesulfonate), [M{Fc(EPh)PPh2}2]X (M = Au, X = ClO4; M = Ag, X = OTf), [M(PPh3){Fc(EPh)PPh2}]OTf (M = Au, Ag), [Au 2{Fc(SPh)PPh2}2](ClO4)2, [Au(C6F5)2{Fc(SePh)PPh2}]ClO 4, [Au(C6F5)3{Fc(EPh)PPh 2}], [Au2(C6F5) 6{Fc(SePh)PPh2}] or [Cu{Fc(EPh)PPh2} 2]PF6 (E = S, Se). In these complexes coordination depends upon the metal centre; with gold it takes place predominantly to the phosphorus atom and with silver and copper to both phosphorus and chalcogen atoms. The treatment of some of the gold complexes with other metal centres affords heterometallic derivatives that in some cases are in equilibrium with the homometallic derivatives. Several compounds have been characterized by X-ray diffraction, four pairs of homologous compounds, yet not a single pair is isotypic. In many of them a three dimensional network is formed through secondary bonds such as hydrogen bonds, Au ... Cl or Au ... Se interactions. The complex [Ag(OTf){Fc(SePh)PPh2}] forms one-dimensional chains through trifluoromethanesulfonate bridging ligands. The Royal Society of Chemistry 2005.
- Aguado, Javier E.,Silvia Canales,Gimeno, Concepcion,Jones, Peter G.,Laguna, Antonio,Dolores Villacampa
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p. 3005 - 3015
(2007/10/03)
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- Aurophilic complexes as gold atom sources in organic media
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The decomposition, either thermal or under H2, of [O(Au1PR3)3](CF3SO3) (R = Ph 1, R = Me 2) in organic solvents has been studied by 31P{1H} NMR, UV-vis spectroscopy an
- Bardaji, Manuel,Uznanski, Pawel,Amiens, Catherine,Chaudret, Bruno,Laguna, Antonio
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p. 598 - 599
(2007/10/03)
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- Synthesis, Structural Characterization, and Luminescence Studies of Gold(I) and Gold (III) Complexes with a Triphosphine Ligand
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We have synthesized a series of trinuclear and tetranuclear gold(I) complexes [(μ-dpmp)(AuX)3] (dpmp = bis-(diphenylphosphinomethyl)phenylphosphine; X = Cl (1), C6F5 (2)), [Au3(μ-dpmp)2](CF3SO3) 3 (3), and [Au4(μ-dpmp)2Cl2](CF3SO 3)2 (4). Complex 4 displays a rhomboidal geometry for the gold atoms with short gold-gold distances of 3.1025(11) and 3.1059(14) A. We have also prepared the mononuclear and dinuclcar gold(III) complexes [(μ-dpmp){Au(C6F5)3}n] (n = 1 (5), 2 (6)). The crystal structure of 5 has been determined by X-ray diffraction studies, which show that gold is coordinated to the central phosphorus although two isomers are observed in solution. Treatment of 6 with gold(I) derivatives affords trinuclear mixed-valence gold(I)-gold(III) [(μ-dpmp)-{Au(C6F5)3}2(AuX)] (X = Cl (7), C6F5 (8)). The luminescent properties of these complexes in the solid state have been studied. Likewise, it has been found that the gold(I) complexes are luminescent but not so the gold-(III) or mixed-valence complexes.
- Bardaji, Manuel,Laguna, Antonio,Victor,Orera,Dolores Villacampa
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p. 5125 - 5130
(2008/10/08)
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- Synthesis of Gold(I) and Gold(II) Complexes with Diphenyl(trimethylsilylmethyl)phosphane
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The reaction of diphenyl(trimethylsilylmethyl)phosphane with [AuCl(tht)] affords the gold(I) complexes [AuCl (PPh2-CH2SiMe3)] (1) or [Au(PPh2CH2SiMe3)2]Cl (2). An X-ray study of 1 does not reveal any Au?Au interaction. Treatment of [Au(tht)2](CF3SO3) or [Au(tht)(PPh3)](CF3SO3) with diphenyl(trimethylsilylmethyl)phosphane results in the displacement of the thioether ligands to give the ionic complexes [Au(PPh2CH2SiMe3)2](CF 3SO3) (3) or [Au(PPh2-CH2SiMe3)(PPh3)](CF 3SO3) (4), the latter mixed with the symmetrical derivatives [Au(PPh2R)2](CF3SO3) (R = Ph, CH2-SiMe3). The molecular structure of complex 3 has been established by X-ray diffraction and shows an antiperiplanar arrangement of the two PR2R′' rotors in the solid state. The reaction of the phosphane ligand with [Au2{μ-(CH2)2-PPh2} 2(tht)2](ClO4)2 affords the dinuclear gold(II) complex [Au2{μ-(CH2)2PPh2} 2(PPh2CH2SiMe3) 2](ClO4)2 (5).
- Bardají, Manuel,Jones, Peter G.,Laguna, Antonio
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p. 989 - 992
(2007/10/03)
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- Synthesis of New Heterodinuclear Aminocarbyne Complexes: Crystal Structures of(C6F5)(CO)2-(η-C5H5)> and Cl(CO)2(η-C5H5)>2>
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The aminocarbyne CN(Et)Me>(CO)2(cp)> 1 (cp = η-C5H5) reacts with (tht = tetrahydrothiophene) and CuCl to give the adducts (C6F5)(CO)2(cp)> 2 and Cl(CO)2(cp)>2> 3 respectively which have been structurally characterized by X-ray diffraction.Complex 2 crystallizes in space group P, a = 9.840(5), b = 11.577(6), c = 8.296(6) Angstroem, α = 99.03(5), β = 91.01(6), γ = 81.92(4) deg, Z = 2.Complex 3 crystallizes in space group P21/a, a = 7.788(2), b = 14.880(5), c = 11.712(5) Angstroem, β = 95.35(3) deg , Z = 2.Both adducts exhibit a molecule of 1 bonded to Au(C6F5) or Cu2Cl2 fragments, respectively, through one of the W-C(carbyne) ? bonds.A WCM ring is formed in which 1 preserves most of its identity and the coinage metals attain their preferred electron counts.The cationic Group 11 fragments (M = Cu, Ag or Au) also react with complex 1 to form (CO)2(cp)>2>(1+) 5; when M = Au NMR spectroscopy indicates that in addition to the trinuclear species 5, the dimetallacyclopropene (CO)2(cp)(PPh3)>(1+) 4 is also present.All these adducts have been spectroscopically characterised.
- Albano, Vincenzo G.,Busetto, Luigi,Cassani, Maria Cristina,Sabatino, Piera,Schmitz, Arndt,Zanotti, Valerio
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p. 2087 - 2094
(2007/10/02)
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