Michel Ephritikhine

Cea Leti, Grenoble, Rhône-Alpes, France

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Publications (316)1072.42 Total impact

  • Jean-Claude Berthet · Pierre Thuery · Michel Ephritikhine

    No preview · Article · Jun 2015 · ChemInform
  • 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.
    No preview · Article · Mar 2015 · Dalton Transactions
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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.
    No preview · Article · Feb 2015 · Inorganic Chemistry
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    ABSTRACT: doi: 10.1021/ic500939t
    No preview · Article · Jun 2014 · Inorganic Chemistry
  • 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.
    No preview · Article · Jun 2014 · Comptes Rendus Chimie
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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.
    Full-text · Article · Apr 2014 · Inorganic Chemistry
  • Alexandre Hervé · Pierre Thuéry · Michel Ephritikhine · Jean-Claude Berthet
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    ABSTRACT: doi: 10.1021/om500252v
    No preview · Article · Apr 2014 · Organometallics
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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.
    Full-text · Article · Feb 2014 · New Journal of Chemistry
  • Jean-Claude Berthet · Pierre Thuéry · Michel Ephritikhine

    No preview · Article · Jan 2014
  • Michel Ephritikhine

    No preview · Article · Jul 2013 · ChemInform
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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.
    No preview · Article · Jun 2013 · Journal of the American Chemical Society
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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.
    No preview · Article · Jun 2013 · Chemical Communications
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    ABSTRACT: This method yields imidazole and pyrimidine derivatives from 1,2- and 1,3-diamino substrates.
    No preview · Article · Jun 2013 · ChemInform
  • 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.
    No preview · Article · Apr 2013 · Comptes Rendus Chimie
  • 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.
    No preview · Article · Mar 2013 · Organometallics
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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%).
    No preview · Article · Mar 2013 · Journal of Materials Chemistry
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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.
    No preview · Article · Feb 2013 · Chemical Communications
  • 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.
    No preview · Article · Jan 2013 · Organometallics
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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.
    No preview · Article · Jan 2013 · ChemCatChem
  • 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.
    No preview · Article · Oct 2012 · Polyhedron

Publication Stats

7k Citations
1,072.42 Total Impact Points


  • 1999-2015
    • Cea Leti
      Grenoble, Rhône-Alpes, France
    • Technion - Israel Institute of Technology
      H̱efa, Haifa, Israel
  • 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
  • 1978-1986
    • Natural Product Chemistry Institute
      Lutetia Parisorum, Île-de-France, France