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Dans le cadre du programme ANR Archeostraits, une cartographie de l'habitat du site archeologique de la Silla del Papa (sud de l'Espagne) a ete entreprise. Elle est rendue complexe par la topographie combinant de forts deniveles et une vegetation persistante. De plus, les bâtiments de la fin de l'âge du fer sont ancres a plusieurs niveaux dans les parois de barres rocheuses, ce qui rend inoperante une analyse architecturale traditionnelle a partir de planimetries en 2D. L'analyse 3D a plusieurs echelles, de l'environnement au sondage, demande une adaptation des outils d'acquisition 3D a cet espace. Trois technologies presentes au sein du laboratoire Traces generant des nuages de points denses ont ete utilisees.

International audience; The paper presents a single-crystal ESR study of a series of pristine and X-ray irradiated (TMTTF)2X salts, where TMTTF is tetramethyltetrathiafulvalene and X is either a centro-symmetrical (SbF6 and Br) or a non-centro-symmetrical (ReO4, ClO4, BF4, SCN and NO3) monovalent anion. Besides standard line-width and spin-susceptibility measurements, the analysis of the asymmetry of the ESR line shape allows to obtain simultaneous information on the electrical conductivity. This whole set of data is used to determine the charge and spin gaps related to the charge ordering (CO) and anion ordering (AO) ground states and their evolution as a function of X-ray irradiation damages. We show in particular that the sensibility of (TMTTF)2X salts to irradiation depends upon the nature of the anion X and that the CO ground state is drastically affected by irradiation damages at the difference of the AO ground state. We also present evidence of a CO transition and of a decoupling between the AO transition and the opening of a spin gap in (TMTTF)2NO3.

International audience; The detailed synthesis of a new series of conjugated TTF ligands with nitrogen-based aromatic heterocycle are presented. In all these molecules, trimethyl-TTF or TTF skeleton are bridged to the nitrogen aromatic ligand through a conjugated spacer such as ethenyl or phenylethenyl unit. Their electrochemical characterization as well as the crystal structure of one of these compounds is given.

6 pages; International audience; We report a preliminary study of two novel complexes combining a paramagnetic transition metal (Cu(II)) and a cyclophane-type TTF-bipyridine ligand TTF-bipy = (cis)2,7-bis(pentylsulfanyl)-3,6- [2,2-bipyridine-bis(4,4-methanediyl)bis-sulfanyl]tetrathiafulvalene. The syntheses of the complexes Cu(hfac)2(TTF-bipy) (hfac = hexafluoroacetylacetonate) and Cu(NO3)2(TTF-bipy)·H2O are reported. The results of single-crystal EPR measurements are discussed on the basis of structural features deduced from preliminary X-ray diffraction data and indicate that these neutral molecular complexes behave as isolated paramagnetic units.

International audience; The title compound, C30H28N2S16, is a precursor to hybrid magnetic materials. The complete molecule is generated by a crystallographic inversion centre. In the crystal structure, the TTF core is not planar and adopts a chair conformation; the two C3S2 rings are folded around the S center dot center dot center dot S hinges, the dihedral angles being 17.14 (8) and 13.46 (7)degrees. There is a short S center dot center dot center dot S contact [3.4863 (14) angstrom] in the crystal structure.

A computational (ZINDO) investigation is employed to estimate the molecular hyperpolarizability (β) of a [(TTF−NH2)8] (TTF = tetrathiafulvalene) octameric stack at various fractional (0 < ρ < 1) oxidation states of TTFρ+. While the neutral [(TTF−NH2)8] octamer exhibits a modest (7.6 × 10-30 cm5 esu-1) static β0 value, in relation to a nearly centrosymmetric electronic structure, the formal (TTF−NH2)0.25+ oxidation state leads to a giant (β0 = 3891 × 10-30 cm5 esu-1 per octamer) NLO response. This effect is related to the appearance of an extremely intense HOMO → LUMO-based low-lying transition, occurring at 1260 nm upon fractional oxidation, thus providing new and unexpected interest in TTF-donor substituted molecules. To illustrate the chemical feasibility of such species, two kinds of derivatives are synthesized: a TTF-dimethylaniline (TTF-DMA) by using in particular a Suzuki cross-coupling reaction between iodo-TTF and p-dimethylaminophenylboronic acid and a TTF-vinyldimethylaniline (TTF-VDMA) by a Wi...

International audience; Une des stratégies possibles pour la synthèse de matériaux moléculaires conducteurs de l'électricité basée sur unsymmetrically substitué tetrathiafulvalenes implique l'utilisation d'un précurseur portant cyanoethylsulfanyl groupes attachés à la tetrathiafulvalene (TTF) de base. The title compound, C 16 H 16 N 2 S 6 , is such a precursor. Le titre composé C 16 H 16 N 2 S 6, est un précurseur. The two cyanoethylsulfanyl groups are attached to the two adjacent C atoms of one of the two C 3 S 2 rings of the TTF core and protrude on both sides of the molecule. Les deux groupes sont cyanoethylsulfanyl fixé aux deux atomes adjacents C de l'un des deux C 3 S 2 anneaux de base et le Fonds saillie sur les deux côtés de la molécule. In the crystal structure, the TTF core is not planar and adopts a boat conformation; the two C 3 S 2 rings are folded around the S Dans la structure cristalline, le Fonds de base ne sont pas planes et adopte un bateau de conformation; Les deux C 3 S 2 anneaux sont pliés autour de la S S hinges, the dihedral angles being 12.19 (6) and 22.70 (4)°. S charnières, les angles de dièdre étant 19/12 (6) et 22.70 (4) °. There are no unusual intermolecular contacts in the solid state. Il n'ya pas inhabituel intermoléculaire des contacts à l'état solide. The crystal studied was a partial inversion twin, with contributions of 0.72 (4) and 0.28 (4) for the two twin domains. Le cristal a été étudié partielle inversion de jumeaux, avec des contributions de 0,72 (4) et 0.28 (4) pour les deux jumeaux domaines.

International audience; A new trimethyltetrathiafulvalene (Me3TTF) derivative Me3TTF-CH=CH-py bearing a pyridyl was synthesized and coordinated to a cobalt(II) benzoate dimer, having paddlewheel core structure, leading to a complex formulated as Co2(PhCOO)4(Me3TTF-CH=CH-py)2. Single-crystal X-ray diffraction studies of the complex performed at 293 and 100 K evidenced the existence of a weak metal-metal interaction. Magnetic studies revealed an antiferromagnetic behavior, which is explained as the result of the direct exchange between metal centers.

International audience; By using two different routes, series of new bis- and tris-TTF, containing in their linker function(s) able to generate supplementary interactions in the resulting materials, have been prepared. The first route based on deprotection-realkylation strategy allowed to introduce alcohol and ketone functions. The second way, using acid chloride and hydroxy-TTF, allowed to include ester function in the linker. The electron-donating ability of this series of TTFs has been determined by CV and by SQW.

International audience; Metallic thin films of the single-component, neutral, molecular solid Ni(tmdt)2 have been prepared by electrocrystallization on passivated silicon substrates. Metallicity is achieved down to 6 K despite the polycrystalline morphology.

cited By 9; International audience; The electrochemical combination of the paramagnetic anion [Cr(NCS)6]3- with the organic π-donors bis(ethylenedithio)tetrathiafulvalene (ET) and 4,5-bis(2-hydroxyethylthio) -4′,5′-ethylenedithiotetrathiafulvalene (DHET-EDTTTF) leads to two new radical cation salts, namely (ET)4 [Cr(NCS 6]·PhCN 1 and (DHET-EDTTTF)2 (NEt4)[Cr(NCS)6] 2. Both have been characterized by X-ray crystallography, magnetic and resistivity measurements. The structure of 1 consists of alternating inorganic layers generated by the anions and organic layers in which the PhCN molecules are inserted; the organic sub-lattice is built up from four different ET units, three of them with a charge distribution of +1, the fourth being neutral. The organic sub-lattice of 2 contains a centrosymmetric [(DHET-EDTTTF•)2]2+ dimer, in which the overlap mode is of the eclipsed type. Conductivity measurements indicate that compounds 1 and 2 are semiconductors with room temperature conductivities of 1.4 × 10-2 and 6.1 × 10-5 S cm-1 and activation energies of 0.24 and 0.23 eV, in 1 and 2, respectively. For both salts, magnetic measurements indicate (i) that the organic and inorganic parts are magnetically independent, and (ii) that the organic units are antiferromagnetically coupled. To cite this article: F. Thétiot et al., C. R. Chimie 6 (2003). © 2003 Académie des sciences. Published by Éditions scientifiques et médicales Elservier SAS. All rights reserved.

We report the observation of superconductivity in the spin-Peierls Fabre salt (TMTTF)2PF6 from pressure dependent electrical transport measurements above a threshold of 4.35 GPa. The data complete the sequence of ground states of this compound in the temperature and pressure plane adducing an empirical basis to the universal character of the phase diagram of the Fabre salts and their selenide analogues, the Bechgaard salts. The structure of the phase diagram at the approach of the crossover between spin-density wave and superconducting states is compared with the results of scaling theory of the interplay between both electronic instabilities under pressure. The comparison supports the view that magnetism and superconductivity in these compounds have a common electronic origin.

Version francaise abregee - Synthese optimisee de l'ethylenedioxotetrathiafulvalene (EDO-TTF) et analyse du role des interactions de van der Waals S…S dans l'organisation cristalline des derives neutres du TTF. La capacite des tetrathiafulvalenes dissymetriques a s'organiser a l'etat solide en dimeres centrosymetriques precurseurs de phases κ nous a conduit a nous interesser a l'ethylenedioxotetrathiafulvalene (EDO-TTF), derive dissymetrique de BEDO-TTF, par analogie avec nos travaux precedents concernant des derives de EDT-TTF. Une synthese efficace de EDO-TTF est decrite, basee sur la decarboxymethylation de EDO-TTF diester a 115 °C. Conduite a 70 °C, cette decarboxylation donne acces au monoester et, a partir de celui-ci, a l'acide carboxylique EDO-TTF-CO 2 H, ainsi qu'aux amides primaire secondaire et tertiaire correspondantes, EDO-TTF-CONRR', R, R' = H, Me, dont les syntheses sont decrites. Des cristaux de qualite et de taille suffisantes ont permis de determiner la structure cristalline de EDO-TTF et de l'acide correspondant EDO-TTF-CO 2 H. EDO-TTF: C 8 H 6 O 2 S 4 ; monoclinique, P2 1 /n; a = 7,177(2), b = 13,433(3), c = 10,925(1) A; β = 99,38(2); V = 1 039,2(4) A˙ 3 ; Z = 4, EDO-TTF-CO 2 H: C 9 H 6 O 4 S 4 ; monoclinique, P2 1 /c; a = 9,711(2), b = 8,529(3), c = 14,557(2) A˙; β = 105,114(10)°; V = 1 163,9(5) A 3 ; Z = 4. L'introduction d'heteroatomes legers comme l'oxygene en lieu et place du soufre dans ces donneurs va ainsi permettre d'evaluer le role joue par les interactions de van der Waals entre chalcogenes dans la stabilisation du mode structural recurrent observe pour la plupart de ces derives du tetrathiafulvalene a l'etat neutre, a savoir une association face a face en diades, avec un recouvrement « liaison sur cycle » et une distance entre plans moyens courte (3.35 A). Alors que les derives soufres et selenies EDT-TTF et EDS-TTF sont isostructuraux. EDO-TTF s'en distingue, d'une part, par ses parametres de maille, mais aussi, d'autre part, par une molecule plus proche de la planarite. par une meme association en diades avec un recouvrement « liaison sur cycle », mais avec une distance entre plans moyens grande (3. H A). malgre la substitution du soufre par l'oxygene, plus petit. Les molecules d'EDO-TTF-CO 2 H sont associees deus a deux a travers un centre d'inversion situe au centre de la pince formee par les deux liaisons hydrogene lortes OH.O et forment le motif caracteristique note R 2 2 (8: dans la nomenclature de M. Etter. Chaque bimolecule (EDO-TTF-CO 2 H) 2 forme avec l'une de ses semblables une diade, avec, ici aussi, une grande distance entre plans moyens (3.55 A). mais aussi un recouvrement inhabituel. La comparaison des structures de EDO-TTF et de EDO-TTF CO 2 H avec leurs analogues soufres ou selenies met donc en avant des comportements bien differents. BEDT-TTF. BEDS-TTF. EDT-TTF. EDS-TTF. et meme la bimolecule (EDT-TTF-CO.H) 2 , s'organisent en dimeres centro-symetriques, avec un couvrement de type liaison sur cycle et une distance inter planaire courte. BEDO TTF, quant a lui, ne forme pas de diades, mais cristallise dans me structure en arete de poisson, rencontree classiquement dans les structures de petits hydrocarbures aromatiques polynucleaires sans heteroatome. decrites par Desiraju.

We present the influence of a transverse magnetic field on the spin-density wave (SDW) ground state of the organic conductor (TMTSF) 2 NO 3 . Magnetic field increases the single-particle activation energy. A finite magnetic field (H C ) induces discontinuities in the magnetoresistance behaviour and its value is temperature dependent. The threshold electric field (E T ) for the SDW sliding increases in a magnetic field. All observed effects are strongly angle-dependent indicating that they are determined by the magnetic field component along the least-conduction (c * ) direction. We discuss these results in the framework of a theoretical model for the SDW with large imperfect nesting

We report a study of the transverse magnetoresistance properties in the spin-density wave (SDW) phase of the organic conductor (TMTSF) 2 NO 3 at temperature down to 1.8 K and in magnetic field up to 6 tesla. The transverse magnetoresistance shows large effect and is highly anisotropic. We analyze our data in the framework of recent theoretical calculations by K. Maki. We suggest that the SDW with large imperfect nesting together with a periodic anion potential might be responsible for the magnetic field effects

We report a study of the transverse-magnetoresistance anisotropy in the spin-density wave phase of the organic conductor (TMTSF)2NO3 at temperatures down to 1.8 K and in fields up to 6 tesla. The transverse magnetoresistance is highly anisotropic and obeys a temperature- and angular-dependent power law behaviour: DELTArho/rho congruent-to H(n) (1 less- than-or-equal-to n < 2). The indication of a possible field-induced SDW phase is discussed. We suggest that the SDW with large imperfect nesting together with a periodic anion potential might be responsible for the observed magnetic-field effects.

The electrical, magnetic and structural properties of several (tTTF)2X salts with X = PF6, AsF6, SbF6, CIO4, ReO4, Br have been investigated. In each case, low temperature phase transitions are found corresponding to the stabilization of various ground states. In the case of salts with the octahedral anions , the antiferromagnetic ground states observed below TN=25 K and 19 K respectively has been characterized by resonance measurements. In the case of the CIO4 salt a structural distortion, probably relaxing the Coulomb repulsions between localized charges, is observed at 137 K. An unusual phase transition affecting both the charge and spin degrees of freedom is observed in the PF6 salt around 50 K. A comparison is made with the properties of the TMTTF salts and related series in order to rationalize these results. Finally the role of the interchain coupling in the competition between the spin-Peierls and antiferromagnetic ground states is emphasized.

The thought modes that children and adolescents develop to solve problems encountered in everyday living are analyzed from two points of view: (1) sources of systematic error in solving mathematics and physics problems, and (2) the possible factors of knowledge development in these fields. Taking into account the gaps in thought modes necessarily involved in gaining access to scientific knowledge, and considering the possible links between the initial conceptions of individuals and the conceptions of experts, the authors discuss some potential means for providing cognitive guidance to foster the development of knowledge.