Michel Ephritikhine

Cea Leti, Grenoble, Rhône-Alpes, France

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Publications (307)1015.35 Total impact

  • Jean-Claude Berthet · Pierre Thuery · Michel Ephritikhine
    ChemInform 06/2015; 46(24):no-no. DOI:10.1002/chin.201524237
  • Michel Ephritikhine · Jean-Claude Berthet · Pierre Thuéry
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    ABSTRACT: This Dalton perspective gives an overview of the development of cyanide chemistry of 4f- and 5f-elements, a field which was poorly explored in contrast to the attention paid to the cyanide complexes of the d transition metals. The use of the cyanide ligand led to the discovery of mono- and polycyanide complexes which exhibit unprecedented and unexpected coordination geometries. A new type of linear metallocenes including [U(Cp*)2(CN)5]3– (Cp* = C5Me5) and the first bent actinocenes [An(Cot)2(CN)]– (An = Th, U; Cot = C8H8) were isolated. Thorocene was found to be much more reactive than uranocene since a series of sterically crowded cyanide complexes have been obtained only from [Th(Cot)2]. A series of cyanido-bridged dinuclear compounds and mononuclear mono-, bis- and tris(cyanide) complexes were prepared by addition of cyanide salts to [MN*3] (M = Ce, U) and [UN*3]+ (N* = N(SiMe3)2]. The CeIII, UIII and UIV ions were clearly differentiated in these reactions by cyanide linkage isomerism, as shown for example by the structures of the cyanide complex [UIIIN*3(CN)2]2– and of the isocyanide derivatives [CeIIIN*3(NC)2]2– and [UIVN*3(NC)]–. While the U−CN/NC coordination preference towards the UIII/UIV pair is related to the subtle balance between steric, covalent and ionic factors, DFT computations and in particular the calculated total bonding energies between the metal and the cyanide ligand allowed the observed coordination mode to be predicted. The ability of the cyanide ligand to stabilize the high oxidation states was assessed with the synthesis of UV and UVI complexes in the inorganic and organometallic series.
    Dalton Transactions 03/2015; 44(17). DOI:10.1039/C5DT00692A · 4.20 Impact Factor
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    ABSTRACT: Treatment of the metallacycle [UN*2(N,C)] [N* = N(SiMe3)2; N,C = CH2SiMe2N(SiMe3)] with [HNEt3][BPh4], [HNEt3]Cl, and [pyH][OTf] (OTf = OSO2CF3) gave the cationic compound [UN*3][BPh4] (1) and the neutral complexes [UN*3X] [X = Cl (3), OTf (4)], respectively. The dinuclear complex [{UN*(μ-N,C)(μ-OTf)}2] (5) and its tetrahydrofuran (THF) adduct [{UN*(N,C)(THF)(μ-OTf)}2] (6) were obtained by thermal decomposition of 4. The successive addition of NEt4CN or KCN to 1 led to the formation of the cyanido-bridged dinuclear compound [(UN*3)2(μ-CN)][BPh4] (7) and the mononuclear mono- and bis(cyanide) complexes [UN*3(CN)] (2) and [M][UN*3(CN)2] [M = NEt4 (8), K(THF)4 (9)], while crystals of [K(18-crown-6)][UN*3(CN)2] (10) were obtained by the oxidation of [K(18-crown-6)][UN*3(CN)] with pyridine N-oxide. The THF adduct of 1, [UN*3(THF)][BPh4], and complexes 2-7, 9 and 10 were characterized by their X-ray crystal structure. In contrast to their U(III) analogues [NMe4][UN*3(CN)] and [K(18-crown-6)]2[UN*3(CN)2] in which the CN anions are coordinated to the metal center via the C atom, complexes 2 and 9 exhibit the isocyanide U-NC coordination mode of the cyanide ligand. This U(III)/U(IV) differentiation has been analyzed using density functional theory calculations. The observed preferential coordinations are well explained considering the electronic structures of the different species and metal-ligand bonding energies. A comparison of the different quantum descriptors, i.e., bond orders, NPA/QTAIM data, and energy decomposition analysis, has allowed highlighting of the subtle balance between covalent, ionic, and steric factors that govern the U-CN/NC bonding.
    Inorganic Chemistry 02/2015; 54(5). DOI:10.1021/acs.inorgchem.5b00034 · 4.79 Impact Factor
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    ABSTRACT: doi: 10.1021/ic500939t
    Inorganic Chemistry 06/2014; 53(13). DOI:10.1021/ic500939t · 4.79 Impact Factor
  • Jean-Claude Berthet · Pierre Thuery · Michel Ephritikhine
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    ABSTRACT: Thorocene [Th(Cot)(2)] (Cot = eta(8)-C8H8) readily reacts with 2,2'-bipyridine to give [Th(Cot)(2)(kappa(2)-bipy)], which has an unusual bent geometry. This compound is rapidly reduced by KC8 into the anionic derivative [(Th(Cot)(2)(kappa(2)-bipy)](-). X-ray diffraction studies suggest the latter to be a Th(IV) compound with the bipyridyl radical anion. These complexes are rare examples of bent actinocene [An(Cot)(2)(L)](q-) (q = 0, 1; An = actinide) and bipyridine-containing thorium species.
    Comptes Rendus Chimie 06/2014; 17(6):526-533. DOI:10.1016/j.crci.2013.09.006 · 1.48 Impact Factor
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    ABSTRACT: Polyazines emerge as highly selective ligands toward actinide versus lanthanide separation. Electronic structures of several mono- and polyazine f-complexes of general formula MX3L (M(+3) = Ce, Nd, Eu, U, Am, and Cm; X = RCp(-) or NO3(-); L = N-donor ligand) related to Ln(III)/An(III) differentiation have been investigated using scalar relativistic ZORA/DFT calculations. In all cases, DFT calculations predict shorter An-N bonds than Ln-N ones whatever the azine used, in good agreement with available experimental data. The An-N bonds are also characterized by higher stretching frequencies than Ln-N bonds. The electronic structures of all species have been studied using different population analyses, among them natural population (NPA) and the quantum theory of atoms in molecule approach (QTAIM), as well as using different bond indices. The ability for Ln(III)/An(III) differentiation of the terdentate bipyrazolate BPPR ligand in the M(BPPR)(NO3)3 complexes (M(3+) = Ce, Eu, U and Am ; R = H, 2,2-dimethylpropyl) where BPP = 2,6-bis(dialkyl-1H-pyrazol-3-yl)pyridine has been studied, with a special emphasis on the total metal-ligand bonding energy (TBE). The ZORA/DFT approach was found to properly reproduce the higher selectivity of the polyazine BPP ligand compared to monoazines, especially for the Eu(III)/Am(III) pair operating in spent nuclear fuel, using computed TBEs as criterion. Moreover, the orbital part of the total bonding energy appears also to rationalize well the observed selectivity.
    Inorganic Chemistry 04/2014; 53(9). DOI:10.1021/ic500361b · 4.79 Impact Factor
  • Alexandre Hervé · Pierre Thuéry · Michel Ephritikhine · Jean-Claude Berthet
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    ABSTRACT: doi: 10.1021/om500252v
    Organometallics 04/2014; 33(8-8):2088-2098. DOI:10.1021/om500252v · 4.25 Impact Factor
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    ABSTRACT: Condensation of 3-hydroxysalicylaldehyde with 2,4,6-trimethyl-1,3-phenylenediamine gives the ligand N,N′-bis(3-hydroxysalicylidene)-2,4,6-trimethyl-m-phenylenediamine (H4L). The dinuclear zinc(II) complex [Zn(H2L)]2 (1) and the tetranuclear copper(II) square complex [{Cu(H2L)}4(THF)] (2) were synthesized and structurally characterized by single crystal X-ray diffraction. In 1, the ZnII ions are bridged by two H2L molecules and they adopt a tetrahedral geometry. The coordination geometry of the copper atoms in 2 is either square planar or square pyramidal, each metal atom being bound to the NO donor sets of two Schiff base ligands and, in one case, to an extra THF molecule. The arrangement of the tetranuclear complexes in the crystal lattice results in the formation of square channels. Variable temperature magnetic measurements on 2 evidence significant long-range ferromagnetic interactions between the four CuII centres leading to an S = 2 ground state with J1 = +5.81, J2 = +2.36, J3 = +1.73 and J4 = +2.37 cm−1. DFT calculations have been carried out in order to corroborate the experimental fitting and ascertain the origin of this ferromagnetic behaviour.
    New Journal of Chemistry 02/2014; 38(3). DOI:10.1039/C3NJ01512B · 3.16 Impact Factor
  • Michel Ephritikhine
    ChemInform 07/2013; 44(27). DOI:10.1002/chin.201327207
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    ABSTRACT: In stark contrast to uranocene, (Cot)2Th reacts with neutral mono- or bi-dentate Lewis bases to give the bent sandwich complexes (Cot)2Th(L) (L = py, 4,4'-bipy, tBuNC, phen, Me4phen). DFT calculations in the gas phase show that, for both U and Th, formation of the bent compound (Cot)2An(L) should be facile, the linear and bent forms being close in energy.
    Journal of the American Chemical Society 06/2013; 135(27). DOI:10.1021/ja4036626 · 11.44 Impact Factor
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    ABSTRACT: Reaction of the linear thorocene with NC(-), N3(-) and H(-) led to the bent derivatives [(Cot)2Th(X)](-) (X = CN, N3) and the bimetallic [{(Cot)2Th}2(μ-H)](-), whereas only [(Cot)2U(CN)](-) could be formed from (Cot)2U.
    Chemical Communications 06/2013; 49(56). DOI:10.1039/c3cc42763c · 6.83 Impact Factor
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    ABSTRACT: This method yields imidazole and pyrimidine derivatives from 1,2- and 1,3-diamino substrates.
    ChemInform 06/2013; 44(23). DOI:10.1002/chin.201323025
  • Michel Ephritikhine
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    ABSTRACT: This article gives an overview of the development of uranium carbene complexes. The first example of these compounds was reported in 1981 with the phosphoylide complex Cp3UCHPMe2Ph but nearly three decades passed before the area witnessed spectacular advances. During this time, actinide methylidene compounds were detected in solid argon, carbenoid uranium species were evidenced in McMurry type reactions, and a series of uranium complexes with N-heterocyclic carbene ligands was isolated. The recent developments in uranium carbene chemistry have to be related to the use of bis-phosphorus stabilized geminal carbon dianions as ligands. Homoleptic complexes and a series of mixed chloro-, tetrahydroborato-, amido-, cyclopentadienyl- and cyclooctatetraenyl-carbene complexes of thorium(IV) and uranium in the +4, +5 and +6 oxidation states have been isolated and characterized. DFT calculations led to a good description of the UC double bond that demonstrates a double σ and π donation toward the metal atom with the involvement of the 5f orbitals.
    Comptes Rendus Chimie 04/2013; 16(4):391–405. DOI:10.1016/j.crci.2012.12.001 · 1.48 Impact Factor
  • Michel Ephritikhine
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    ABSTRACT: The ubiquity of the cyclopentadienyl ligand permits us to use its complexes as representative examples for the description of recent highlights in organometallic and more generally in coordination chemistry of the actinides. Uranium(III) complexes exhibit a remarkable reactivity, especially in the activation of small molecules, and are valuable precursors of higher valent derivatives. Using redox-active ligands led to the design of reactive complexes which have been considered as “synthons” of AnII and AnIII (An = Th, U). Studies of low-valent compounds gave a better insight into lanthanide(III)/actinide(III) differentiation. Organoactinide(IV) complexes with the bis-Cp* platform play a major role in the synthesis of a variety of compounds containing single and double metal–ligand bonds, revealing novel structures and reactions. The bis(cyclopentadienyl) uranium(IV) and thorium(IV) complexes were also found to be quite efficient in catalytic processes. Cyclopentadienyl complexes afford systems in which actinide ions potentially engage in magnetic exchange interactions. Organoactinide complexes in the +5 and +6 oxidation states remain relatively rare, and most of these are cyclopentadienyl derivatives with oxo and imido ligands.
    Organometallics 03/2013; 32(9):2464–2488. DOI:10.1021/om400145p · 4.25 Impact Factor
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    ABSTRACT: Four novel phenyl-end-capped p-conjugated polymers comprising alkyl chains of different lengths were synthesized: the poly(9,9-dihexyl-2,7-fluorene-alt-9,9-dioctylfluorene) (P0), the alternating fluorene– carbazole copolymers P1 and P2 comprising 20% and 50% of carbazole, respectively, and the homopolymer poly(9-hexyl-9H-carbazole) (P3). The non-end-capped alternating fluorene–carbazole copolymer P4 comprising 20% of carbazole was also synthesized for the sake of comparison with P1. P0–P2 and P4 were synthesized by a Pd-catalyzed Suzuki–Miyaura coupling in good yields (80–89%), while P3 was obtained by a Ni-catalyzed Yamamoto coupling reaction from the 3,6-dibromocarbazole monomer in a moderate yield (52%). P0–P4 polymers were characterized by NMR, elemental analysis, and GPC. The molecular weights are 40.30, 23.42, 14.33, 3.92, and 37.49 kDa, with polydispersity indices of 2.5, 1.7, 1.8, 1.3, and 2.6, for P0, P1, P2, P3, and P4, respectively. These polymers were found to show a high thermal stability, with decomposition temperatures in the range of 395–420 C, and the glass transition temperature was found to regularly increase with the amount of carbazole inserted in the conjugated backbone. AFM images obtained on thin films (thickness of about 90 nm) of P0–P2 revealed films with surfaces of good quality, being homogeneous with low roughness (0.2 nm for the smaller ones). These polymers were found to be blue-emitting both in diluted dichloromethane and chlorobenzene solutions as well as in thin films and exhibit relatively high values of the absolute quantum yields in the range of 100–5.5% in dichloromethane and 51.4–7.7% in thin films. Blue-emitting electroluminescent devices were obtained with P0 and P1 as emitting layers, respectively. The device built with P1 showed improved performances (EQE of 1.32%) with respect to the one built with the parent polyfluorene material (EQE of 0.75%).
    Journal of Materials Chemistry 03/2013; 1(19). DOI:10.1039/c3tc00060e · 7.44 Impact Factor
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    ABSTRACT: The first examples of inorganic nitrite complexes of the natural actinides are described, including the structures of the homoleptic thorium(iv) [PPh(4)](2)[Th(NO(2))(6)] and the uranyl(vi) [PPh(4)](2)[UO(2)(NO(2))(4)] complexes; the nitrite ligand can adopt two different coordination modes in the coordination sphere of the uranyl ion and is unstable towards reduction.
    Chemical Communications 02/2013; 49(24):2412-4. DOI:10.1039/c3cc39163a · 6.83 Impact Factor
  • Florian Dulong · Pierre Thuéry · Michel Ephritikhine · Thibault Cantat
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    ABSTRACT: Two examples of N-aryloxy-β-diketiminate dianions (11a,b) have been synthesized on a multigram scale, in four steps, from commercially available chemicals. The synthetic scheme relies on the sequential addition of 2,6-diisopropylaniline and 2-amino-4-tert-butylphenol (1a) (or 2-amino-4,6-di-tert-butylphenol (1b)) to acetylacetone, using Et3OBF4 as an activation reagent. Both the nature of the activation reagent and the order of addition of the primary amines have a major impact on the outcome of the reaction, and acid catalysts (such as sulfuric acid or p-toluenesulfonic acid) lead to decomposition of the β-diketiminate backbone via formation of a benzoxazole derivative (3a,b). Using dianions 11a,b, mono- and bis(N-aryloxy-β-diketiminate) complexes of zirconium(IV), ytterbium(III), thorium(IV), and uranium(IV) have been synthesized (12–18), by salt metathesis reactions, and characterized by a combination of 1H/13C NMR spectroscopy, elemental analysis, and X-ray crystallography. The two ligands differ in their steric bulk and exhibit different coordination behaviors, which were rationalized on the basis of geometric considerations.
    Organometallics 01/2013; 32(5):1328–1340. DOI:10.1021/om3010355 · 4.25 Impact Factor
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    ABSTRACT: C 1 , seen them all: A catalytic transformation that uses CO2 as an oxygen‐free C1 building block is presented. The reductive functionalization of CO2 is promoted by N‐heterocyclic carbenes or guanidines as organocatalysts in the presence of amines and hydrosilanes. This diagonal strategy selectively affords benzimidazoles, quinazolinones, 3,4‐dihydroquinazolines, formamidines, and their derivatives, directly from CO2 under mild conditions.
    ChemCatChem 01/2013; 5(1). DOI:10.1002/cctc.201200732 · 5.04 Impact Factor
  • Claude Villiers · Pierre Thuéry · Michel Ephritikhine
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    ABSTRACT: 2,3-Dimethyl-2,3-butanediol (pinacol, L1) reacted with uranyl nitrate and acetate hydrates to give [UO2(NO3)2(L1)]·L1 (1·L1) and [UO2(OAc)2(L1)] (2), while 2,5-dimethyl-3,4-di-iso-propyl-3,4-hexanediol (L2) was found to undergo a pinacol rearrangement into the ketone R3CCOR (R = iPr) in the presence of uranyl complexes. Treatment of [UO2(NO3)2(H2O)2]·4H2O with tetrahydrofurfuryl alcohol (L3) and α,α-ditertiobutyltetrahydrofurfuryl alcohol (L4) led to the formation of [UO2(NO3)2(L3)]·H2O (3·H2O) and [UO2(NO3)2(L4)] (4). The crystal structures show that the metal coordination is similar in the 1,2-diol and ether–alcohol complexes but, in contrast to 1·L1, 2 and 3·H2O which form one- or two-dimensional hydrogen bonded assemblages, the structure of 4 is composed of discrete molecules, due to the lack of intermolecular hydrogen bonds. The crystal structure of uncomplexed L2 is also described.
    Polyhedron 10/2012; 46(1):133-138. DOI:10.1016/j.poly.2012.07.100 · 2.05 Impact Factor
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    ABSTRACT: Complexation studies of MX3 (M = Ce, U; X = I, OTf) with 1,10-phenanthroline (phen), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4phen) and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in pyridine (py) and acetonitrile reveal the major influence of the counter-ion X and solvent on ligand coordination. By comparison with bipy and terpy analogues (bipy = 2,2′-bipyridine; terpy = 2,2′:6′,2″-terpyridine), the phen and tptz complexes permit to address the effects of the preorganization, basicity and softness of these bi- and terdentate ligands on the coordination behaviour of the trivalent cerium and uranium ions.Addition of phen to MX3 (M = Ce, U; X = I, OTf) in pyridine or acetonitrile led to the formation of the mono-, bis- and tris-phen adducts. The tetrakis-phen derivatives were also obtained except for X = I in the more coordinating solvent pyridine. The greater affinity of phen for M(OTf)3 than for MI3 reflects the stronger Lewis acidity of the metal centre. The X-ray crystal structures of CeI3(phen)2(py)·py (1a·py), [CeI2(phen)2(py)2][I] (1b), UI3(phen)2(py)·1.5py (1c·1.5py), [CeI2(phen)3][I]·MeCN (2a·MeCN)], [UI2(phen)3][I]·MeCN (2b·MeCN), [M(phen)4(MeCN)2][I]3·xMeCN [M = Ce (3a·2MeCN) and U (3b·4MeCN)], Ce(OTf)3(phen)2(py)2·py (4·py), Ce(OTf)3(phen)3·2py (5a·2py), Ln(OTf)3(phen)3·py (L = Pr, Nd, Sm) and [M(OTf)2(phen)4][OTf] [M = Ce (6a) and U (6b)] were determined. The OTf− anion is a better ligand than I− and the complexes are generally less dissociated in ion pairs, as shown by the bis-phen and tris-phen complexes 4 and 5 which are neutral instead of cationic in 1b and 2, and the tetrakis-phen complexes 6 which are monocationic instead of tricationic in 3.The bis-Me4phen complexes MI3(Me4phen)2(py) [M = Ce (7a) and U (7b)] were obtained by treatment of MI3 with Me4phen in pyridine, while similar reaction with Ce(OTf)3 gave Ce(OTf)3(Me4phen)2(py)2 (8a) in pyridine and [Ce(OTf)2(Me4phen)2(μ2-OTf)]2 (8b) in acetonitrile, clearly reflecting the weaker coordinating capacity of MeCN. In contrast to that observed with the MI3/phen system, the tetrakis-Me4phen derivatives [MI(Me4phen)4][I]2 [M = Ce (9a) or U (9b)] could be obtained in pyridine, as well as in acetonitrile, in line with the stronger basicity of Me4phen compared to phen. In contrast to CeI3, no difference was observed in the coordination of 4 equiv of phen or Me4phen to Ce(OTf)3 and crystals of [Ce(OTf)2(Me4phen)4][OTf]·3py (10·3py) were deposited from a pyridine solution. Solvates of complexes 7–10 have been crystallographically characterized.Treatment of LnX3 (Ln = Ce, Nd; X = I, OTf) in pyridine or acetonitrile with tptz afforded mono and bis-adducts and the crystal structures of solvates of CeI3(tptz)(MeCN)2 (11a), Ce(OTf)3(tptz)2 (14), [NdI2(tptz)2(py)][I] (15), [CeI2(tptz)2(H2O)][I] (16), and 0.8CeI3(tptz)2·0.2[CeI2(tptz)2(MeCN)][I]·0.5MeCN (18) were determined. Addition of 3 equiv of tptz to CeX3 did not afford tris–tptz complexes except in the case of X = I in acetonitrile, affording crystals of [CeI(tptz)3][I]2·2MeCN (20a·2MeCN). By comparison with the terpy analogues, the 1H NMR spectra and crystal structures of the tptz compounds reveal the weaker basicity and electron donating capacity of tptz. While treatment of CeI3 with tptz or terpy and treatment of UI3 with terpy led to the formation of the corresponding Lewis base adducts, UI3 reacted with 1 equiv of tptz in acetonitrile to give the dinuclear uranium(IV) oxidation compound {UI3(MeCN)}2(μ-tptz–tptz) (21a) resulting from electron transfer from the UIII ion to the azine molecule, followed by dimerization of the anion-radical tptz−. In the presence of 2 equiv of tptz in pyridine, the UIII → UIV oxidation did not occur with the less electron rich U(OTf)3 which was transformed into U(OTf)3(tptz)2·2py (22·2py) and {U(OTf)2(tptz)2}2(μ-OTf)2·2py (23·2py). Crystal structures of 21–23 have been determined.
    Polyhedron 09/2012; 45(1):107-125. DOI:10.1016/j.poly.2012.07.040 · 2.05 Impact Factor

Publication Stats

5k Citations
1,015.35 Total Impact Points

Institutions

  • 1994–2015
    • Cea Leti
      Grenoble, Rhône-Alpes, France
    • University of Liège
      • Laboratory of Analytical Chemistry
      Luik, Walloon, Belgium
  • 1989–2014
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1991–2013
    • DSM Biomedical
      Exton, Pennsylvania, United States
  • 1996–2011
    • Atomic Energy and Alternative Energies Commission
      Fontenay, Île-de-France, France
  • 2008
    • Laboratoire de Chimie de Coordination.
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2006
    • Université de Rennes 1
      Roazhon, Brittany, France
  • 2003–2005
    • University of Angers
      Angers, Pays de la Loire, France
  • 2004
    • Sapienza University of Rome
      • Department of Chemistry
      Roma, Latium, Italy
  • 1978–1986
    • Natural Product Chemistry Institute
      Lutetia Parisorum, Île-de-France, France