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Reactivity of Pd3(dppm)3(CO) n+ and Pd3(dppm)3(CO)(RCCR) n+ (n = 0, +1, +2) Towards F−. Evidence of Reactive Intermediates and X-Ray Structure of [Pd3(dppm)3(MeO2CC≡CCO2Me)(F)]PF6. J CLUST SCI 2010. [DOI: 10.1007/s10876-010-0338-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Salomon C, Dal Molin S, Fortin D, Mugnier Y, Boeré RT, Jugé S, Harvey PD. The first unpaired electron placed inside a C3-symmetry P-chirogenic cluster. Dalton Trans 2010; 39:10068-75. [DOI: 10.1039/c0dt00542h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Dal Molin S, Cugnet C, Brevet D, Lucas D, Mugnier Y, Fortin D, Boeré RT, Harvey PD. Enhanced Stability of a Paramagnetic Palladium Complex Promoted by Interactions with Ethynyl Substrates. Organometallics 2007. [DOI: 10.1021/om700377a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sophie Dal Molin
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - Cyril Cugnet
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - David Brevet
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - Dominique Lucas
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - Yves Mugnier
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - Daniel Fortin
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - René T. Boeré
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
| | - Pierre D. Harvey
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France, Département de Chimie, Université de Sherbrooke, Sherbrooke J1K 2R1, Québec, Canada, and the Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge T1K 3M4, Alberta, Canada
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Cugnet C, Lucas D, Collange E, Hanquet B, Vallat A, Mugnier Y, Soldera A, Harvey PD. Generation, Characterization, and Electrochemical Behavior of the Palladium–Hydride Cluster [Pd3(dppm)3(μ3-CO)(μ3-H)]+ (dppm=Bis(diphenylphosphinomethane). Chemistry 2007; 13:5338-46. [PMID: 17455171 DOI: 10.1002/chem.200700069] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Addition of formate on the dicationic cluster [Pd(3)(dppm)(3)(mu(3)-CO)](2+) (dppm=bis(diphenylphosphinomethane) affords quantitatively the hydride cluster [Pd(3)(dppm)(3)(mu(3)-CO)(mu(3)-H)](+). This new palladium-hydride cluster has been characterised by (1)H NMR, (31)P NMR and UV/Vis spectroscopy and MALDI-TOF mass spectrometry. The unambiguous identification of the capping hydride was made from (2)H NMR spectroscopy by using DCO(2) (-) as starting material. The mechanism of the hydride complex formation was investigated by UV/Vis stopped-flow methods. The kinetic data are consistent with a two-step process involving: 1) host-guest interactions between HCO(2) (-) and [Pd(3)(dppm)(3)(mu(3)-CO)](2+) and 2) a reductive elimination of CO(2). Two alternatives routes to the hydride complex were also examined : 1) hydride transfer from NaBH(4) to [Pd(3)(dppm)(3)(mu(3)-CO)](2+) and 2) electrochemical reduction of [Pd(3)(dppm)(3)(mu(3)-CO)](2+) to [Pd(3)(dppm)(3)(mu(3)-CO)](0) followed by an addition of one equivalent of H(+). Based on cyclic voltammetry, evidence for a dual mechanism (ECE and EEC; E=electrochemical (one-electron transfer), C=chemical (hydride dissociation)) for the two-electron reduction of [Pd(3)(dppm)(3)(mu(3)-CO)(mu(3)-H)](+) to [Pd(3)(dppm)(3)(mu(3)-CO)](0) is provided, corroborated by digital simulation of the experimental results. Geometry optimisations of the [Pd(3)(H(2)PCH(2)PH(2))(3)(mu(3)-CO)(mu(3)-H)](n) model clusters were performed by using DFT at the B3 LYP level. Upon one-electron reductions, the Pd--Pd distance increases from a formal single bond (n=+1), to partially bonding (n=0), to weak metal-metal interactions (n=-1), while the Pd--H bond length remains relatively the same.
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Affiliation(s)
- Cyril Cugnet
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
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Cugnet C, Mugnier Y, Dal Molin S, Brevet D, Lucas D, Harvey PD. Thermal and Electrochemically Assisted Pd−Cl Bond Cleavage in the d9−d9 Pd2(dppm)2Cl2 Complex by Pd3(dppm)3(CO)n+ Clusters (n = 2, 1, 0). Inorg Chem 2007; 46:3083-8. [PMID: 17371010 DOI: 10.1021/ic061777h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new aspect of reactivity of the cluster [Pd3(dppm)3(micro3-CO)]n+, ([Pd3]n+, n = 2, 1, 0) with the low-valent metal-metal-bonded Pd2(dppm)2Cl2 dimer (Pd2Cl2) was observed using electrochemical techniques. The direct reaction between [Pd3]2+ and Pd2Cl2 in THF at room temperature leads to the known [Pd3(dppm)3(micro3-CO)(Cl)]+ ([Pd3(Cl)]+) adduct and the monocationic species Pd2(dppm)2Cl+ (very likely as Pd2(dppm)2(Cl)(THF)+, [Pd2Cl]+) as unambiguously demonstrated by UV-vis and 31P NMR spectroscopy. In this case, [Pd3]2+ acts as a strong Lewis acid toward the labile Cl- ion, which weakly dissociates from Pd2Cl2 (i.e., dissociative mechanism). Host-guest interactions between [Pd3]2+ and Pd2Cl2 seem unlikely on the basis of computer modeling because of the strong screening of the Pd-Cl fragment by the Ph-dppm groups in Pd2Cl2. The electrogenerated clusters [Pd3]+ and [Pd3]0 also react with Pd2Cl2 to unexpectedly form the same oxidized adduct, [Pd3(Cl)]+, despite the known very low affinity of [Pd3]+ and [Pd3]0 toward Cl- ions. The reduced biproduct in this case is the highly reactive zerovalent species "Pd2(dppm)2" or "Pd(dppm)" as demonstrated by quenching with CDCl3 (forming the well-known complex Pd(dppm)Cl2) or in presence of dppm (forming the known Pd2(dppm)3 d10-d10 dimer). To bring these halide-electron exchange reactions to completion for [Pd3]+ and [Pd3]0, 0.5 and 1.0 equiv of Pd2Cl2 are necessary, respectively, accounting perfectly for the number of exchanged electrons. The presence of a partial dissociation of Pd2Cl2 into the Cl- ion and the monocation [Pd2Cl]+, which is easier to reduce than Pd2Cl2, is suggested to explain the overall electrochemical results. It is possible to regulate the nature of the species formed from Pd2Cl2 by changing the state of charge of the title cluster.
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Affiliation(s)
- Cyril Cugnet
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR CNRS 5260, Université de Bourgogne, Faculté des Sciences Mirande, Dijon, France
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Cugnet C, Lucas D, Lemaître F, Collange E, Soldera A, Mugnier Y, Harvey PD. Unexpected reaction of the unsaturated cluster host and catalyst [Pd3(mu3-CO)(dppm)3]2+ with the hydroxide ion: spectroscopic and kinetic evidence of an inner-sphere mechanism. Chemistry 2006; 12:8386-95. [PMID: 16897803 DOI: 10.1002/chem.200600395] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The title cluster, [Pd(3)(mu(3)-CO)(dppm)(3)](2+) (dppm=bis(diphenylphosphino)methane), reacts with one equivalent of hydroxide anions (OH(-)), from tetrabutylammonium hydroxide (Bu(4)NOH), to give the paramagnetic [Pd(3)(mu(3)-CO)(dppm)(3)](+) species. Reaction with another equivalent of OH(-) leads to the zero-valent compound [Pd(3)(mu(3)-CO)(dppm)(3)](0). From electron paramagnetic resonance analysis of the reaction medium using the spin-trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the 2-tetrahydrofuryl or methyl radicals, deriving from the tetrahydrofuran (THF) or dimethyl sulfoxide (DMSO) solvent, respectively, were detected. For both [Pd(3)(mu(3)-CO)(dppm)(3)](2+) and [Pd(3)(mu(3)-CO)(dppm)(3)](+), the mechanism involves, in a first equilibrated step, the formation of a hydroxide adduct, [Pd(3)(mu(3)-CO)(dppm)(3)(OH)]((n-1)+) (n=1, 2), which reacts irreversibly with the solvent. The kinetics were resolved by means of stopped-flow experiments and are consistent with the proposed mechanism. In the presence of an excess of Bu(4)NOH, an electrocatalytic process was observed with modest turnover numbers (7-8). The hydroxide adducts [Pd(3)(mu(3)-CO)(dppm)(3)(OH)]((n-1)+) (n=1, 2), which bear important similarities to the well-known corresponding halide adducts [Pd(3)(mu(3)-CO)(dppm)(3)(mu(3)-X)](n) (X=Cl, Br, I), have been studied by using density functional theory (DFT). Although the optimised geometry for the cluster in its +2 and 0 oxidation states (i.e., cation and anion clusters, respectively) is the anticipated mu(3)-OH form, the paramagnetic species, [Pd(3)(mu(3)-CO)(dppm)(3)(OH)](0), shows a mu(2)-OH form; this suggests an important difference in electronic structure between these three species.
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Affiliation(s)
- Cyril Cugnet
- Université de Bourgogne, Laboratoire de Synthèse et Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, 9 Avenue Alain Savary, 21000 Dijon, France
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Electrochemical reduction properties of A-frame compounds and crystal structure of Pd2(dppm)2(Me)2(Br)+ dimer. Inorganica Chim Acta 2006. [DOI: 10.1016/j.ica.2005.09.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Brevet D, Lucas D, Richard P, Vallat A, Mugnier Y, Harvey PD. Formation and X-ray structure of the hostguest adduct [Pd3(dppm)3(CO)(NO3)]+ and the mechanism of its electrochemical reduction. CAN J CHEM 2006. [DOI: 10.1139/v05-249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
[Pd3(dppm)3(CO)]2+, [Pd3]2+, reacts with NO3 to form the hostguest adduct [Pd3(dppm)3(CO)(NO3)]+, [Pd3(NO3)]+. The presence of NO3 inside the cavity is confirmed by X-ray crystallography. Using a qualitative relationship between λmax (UVvis) and the association constant of various adducts, the relative binding between NO3 and [Pd3]2+ is in the same order of magnitude of that between CF3CO2 and [Pd3]2+. Based on Pd···O distances, the NO3 ion is relativity more weakly associated to [Pd3]2+ in comparison with the known [Pd3(CF3CO2)]+. Using variation of [NO3] in the presence of [Pd3](PF6)2 and variation of scan rates, the resulting cyclic voltammogramms (CV) were simulated to extract both kinetic and thermodynamic constants associated to a square scheme. Both the anodic and cathodic scans of the title cluster exhibits ECE mechanisms (E = electrochemical process; C = chemical process). For the anodic scan, the EEC event is not ruled out, at least as a minor process.Key words: nitrate, palladium cluster, adduct, electrochemistry, X-ray structure, rate constant, equilibrium constant.
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Lucas D, Lemaître F, Gallego‐Gómez B, Cugnet C, Richard P, Mugnier Y, Harvey PD. New Insights into the Stoichiometric and Catalytic Reactivity of Unsaturated Pd
3
(dppm)
3
CO
n
+
Clusters (
n
= 0, 1) Towards Halocarbons – First Evidence for Inorganic By‐Products. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200400594] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dominique Lucas
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France, Fax: +33‐380‐39‐36‐64
| | - Frédéric Lemaître
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France, Fax: +33‐380‐39‐36‐64
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1, Fax: +1‐819‐821‐8017
| | - Beatriz Gallego‐Gómez
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France, Fax: +33‐380‐39‐36‐64
| | - Cyril Cugnet
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France, Fax: +33‐380‐39‐36‐64
| | - Philippe Richard
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France, Fax: +33‐380‐39‐36‐64
| | - Yves Mugnier
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France, Fax: +33‐380‐39‐36‐64
| | - Pierre D. Harvey
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1, Fax: +1‐819‐821‐8017
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Brevet D, Mugnier Y, Lemaître F, Lucas D, Samreth S, Harvey PD. Stoichiometric and catalytic activation of the alpha- and beta-2,3,4-tri-O-acetyl-5-thioxylopyranosyl bromide inside the cavity of the Pd3(dppm)3(CO)2+ cluster. Inorg Chem 2003; 42:4909-17. [PMID: 12895115 DOI: 10.1021/ic026279x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The title cluster (Pd(3)(2+)) exhibits a pronounced affinity for Br(-) ions to form the very stable Pd(3)(Br)(+) adduct. Upon a 2-electron reduction, a dissociative process occurs generating Pd(3)(0) and eliminating Br(-) according to an ECE mechanism (electrochemical, chemical, electrochemical). At a lower temperature (i.e. -20 degrees C), both ECE and EEC processes operate. This cluster also activates the C-Br bond, and this work deals with the reactivity of Pd(3)(2+) with 2,3,4-tri-O-acetyl-5-thioxylopyranosyl bromide (Xyl-Br), both alpha- and beta-isomers. The observed inorganic product is Pd(3)(Br)(+) again, and it is formed according to an associative mechanism involving Pd(3)(2+).Xyl-Br host-guest assemblies. In an attempt to render the C-Br bond activation catalytic, these species are investigated under reduction conditions at two potentials (-0.9 and -1.25 V vs SCE). In the former case, the major product is Xyl-H, issued from a radical intermediate Xyl(*) abstracting an H atom from the solvent. Evidence for Xyl(*) is provided by the trapping with TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) and DMPO (5,5'-dimethylpyrroline-N-oxyde). In the second case, only one product is observed, 3,4-di-O-acetyl-5-thioxylal, which is issued from the Xyl(-)() intermediate anion.
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Affiliation(s)
- David Brevet
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5632, Faculté des Sciences Gabriel, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France
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Lemaître F, Lucas D, Groison K, Richard P, Mugnier Y, Harvey PD. Thermal and electrochemical C-X activation (X = Cl, Br, I) by the strong Lewis acid Pd3(dppm)3(CO)2+ cluster and its catalytic applications. J Am Chem Soc 2003; 125:5511-22. [PMID: 12720466 DOI: 10.1021/ja0297786] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The stoichiometric and catalytic activations of alkyl halides and acid chlorides by the unsatured Pd(3)(dppm)(3)(CO)(2+) cluster (Pd(3)(2+)) are investigated in detail. A series of alkyl halides (R-X; R = t-Bu, Et, Pr, Bu, allyl; X = Cl, Br, I) react slowly with Pd(3)(2+) to form the corresponding Pd(3)(X)(+) adduct and "R(+)". This activation can proceed much faster if it is electrochemically induced via the formation of the paramagnetic species Pd(3)(+). The latter is the first confidently identified paramagnetic Pd cluster. The kinetic constants extracted from the evolution of the UV-vis spectra for the thermal activation, as well as the amount of electricity to bring the activation to completion for the electrochemically induced reactions, correlate the relative C-X bond strength and the steric factors. The highly reactive "R(+)" species has been trapped using phenol to afford the corresponding ether. On the other hand, the acid chlorides react rapidly with Pd(3)(2+) where no induction is necessary. The analysis of the cyclic voltammograms (CV) establishes that a dissociative mechanism operates (RCOCl --> RCO(+) + Cl(-); R = t-Bu, Ph) prior to Cl(-) scavenging by the Pd(3)(2+) species. For the other acid chlorides (R = n-C(6)H(13), Me(2)CH, Et, Me, Pr), a second associative process (Pd(3)(2+) + RCOCl --> Pd(3)(2+.....)Cl(CO)(R)) is seen. Addition of Cu(NCMe)(4)(+) or Ag(+) leads to the abstraction of Cl(-) from Pd(3)(Cl)(+) to form Pd(3)(2+) and the insoluble MCl materials (M = Cu, Ag) allowing to regenerate the starting unsaturated cluster, where the precipitation of MX drives the reaction. By using a copper anode, the quasi-quantitative catalytic generation of the acylium ion ("RCO(+)") operates cleanly and rapidly. The trapping of "RCO(+)" with PF(6)(-) or BF(4)(-) leads to the corresponding acid fluorides and, with an alcohol (R'OH), to the corresponding ester catalytically, under mild conditions. Attempts were made to trap the key intermediates "Pd(3)(Cl)(+)...M(+)" (M(+) = Cu(+), Ag(+)), which was successfully performed for Pd(3)(ClAg)(2+), as characterized by (31)P NMR, IR, and FAB mass spectrometry. During the course of this investigation, the rare case of PF(6)(-) hydrolysis has been observed, where the product PF(2)O(2)(-) anion is observed in the complex Pd(3)(PF(2)O(2))(+), where the substrate is well-located inside the cavity formed by the dppm-Ph groups above the unsatured face of the Pd(3)(2+) center. This work shows that Pd(3)(2+) is a stronger Lewis acid in CH(2)Cl(2) and THF than AlCl(3), Ag(+), Cu(+), and Tl(+).
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Affiliation(s)
- Frédéric Lemaître
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5632, Faculté des Sciences Gabriel, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France
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Réactivité du bromure de 5-thioxylopyranosyle et du 1,5-dithioxylopyranoside vis-à-vis d’anions thiolate. CR CHIM 2003. [DOI: 10.1016/s1631-0748(03)00074-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Lemaître F, Lucas D, Mugnier Y, Harvey PD. The Pd3(dppm)3(CO)2+ cluster: an efficient electrochemically assisted Lewis acid catalyst for the fluorination and alcoholysis of acyl chlorides. J Org Chem 2002; 67:7537-40. [PMID: 12375992 DOI: 10.1021/jo026237q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dicationic palladium cluster Pd3(dppm)3(CO)2+ (dppm = bis(diphenylphosphino)methane) reacts with acid chlorides RCOCl (R = n-C6H13, t-Bu, Ph) to afford quantitatively the chloride adduct Pd3(dppm)3(CO)(Cl)+ and the acyl cation RCO+ as the organic counterpart. The dicationic reactive cluster can be reformed by electrolyzing the chloride complex with a copper anode leaving CuCl as a byproduct. The combination of these two reactions provides an electrocatalytic way to form the acylium from the acid chloride. Indeed, in CH2Cl2, 0.2 M NBu4PF6, or NBu4BF4, the electrolysis of the acid chloride in the presence of a catalytic amount of the cluster (1%) gives in good yields the acid fluoride RCOF, arising from the coupling of the acylium with a F(-) issued from the fluorinated supporting electrolyte. Alternatively, in CH2Cl2 or 0.2 M NBu4ClO4, by operating with an alcohol R'OH as the nucleophile, the electrolysis gives the ester RC(O)OR' as the only final product.
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Affiliation(s)
- Frédéric Lemaître
- Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, CNRS UMR 5632, Faculté des Sciences Gabriel, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France
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