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An Efficient, Redox-Enhanced Pair of Hydrogen-Bond Tweezers for Chloride Anion Recognition, a Key Synthon in the Construction of a Novel Type of Organic Metal based on the Secondary Amide-Functionalized Ethylenedithiotetrathiafulvalene, β‘ ‘-(EDT-TTF-CONHMe) 2 [Cl·H 2 O]

Abstract : Electrocrystallization of 1,1,2-trichloroethane solutions of the redox-active secondary amide, 3-methylamido-3‘,4‘-ethylenedithiotetrathiafulvalene (EDT-TTF-CONHMe 1) in the presence of n-Bu4NF supported on silica gel afforded a mixed-valence chloride salt, formulated (1)2[Cl·H2O] from elemental analysis and X-ray crystal structure resolution. The chloride anion and water molecule are disordered on the same site, and coordinated to the π-donor molecule by two strong hydrogen bonds involving the amidic N−H and the aromatic C−H group ortho to the amide, thereby qualifying a robust pair of tweezers-like cyclic motif. This efficient anion recognition effect is also observed in solution, as demonstrated by 1H NMR downfield shifts of both the N−H and C−H hydrogen atom resonances, as well as by a cathodic shift of the oxidation potential of 1 upon Cl- complexation, establishing that the actual electrocrystallized species is a solvated anionic chloride complex [(1·Cl-)(H2O)n] rather than the free amide. (1)2[Cl·H2O] adopts a layered β‘ ‘-type structure with segregation of the hydrophobic (EDT-TTF) and hydrophilic (amide, Cl-, H2O) fragments. The HOMO−HOMO intermolecular interaction energies for the donor layers are large and the Fermi surface exhibits a pronounced two-dimensional character. The EPR Dysonian line observed below 120 K indicates an highly conducting system, confirmed by high room-temperature conductivity of 120 S cm-1 and metallic behavior down to 0.47 K, with a 167-fold increase of the conductivity, but no indication however of a transition to a superconducting state, a likely consequence of the Cl-/H2O disorder.
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https://hal.univ-angers.fr/hal-02546078
Contributeur : Cécile Meziere <>
Soumis le : vendredi 17 avril 2020 - 16:42:16
Dernière modification le : mercredi 16 septembre 2020 - 16:40:15

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Karine Heuzé, Cécile Mézière, Marc Fourmigué, Patrick Batail, Claude Coulon, et al.. An Efficient, Redox-Enhanced Pair of Hydrogen-Bond Tweezers for Chloride Anion Recognition, a Key Synthon in the Construction of a Novel Type of Organic Metal based on the Secondary Amide-Functionalized Ethylenedithiotetrathiafulvalene, β‘ ‘-(EDT-TTF-CONHMe) 2 [Cl·H 2 O]. Chemistry of Materials, American Chemical Society, 2000, 12 (7), pp.1898-1904. ⟨10.1021/cm000143k⟩. ⟨hal-02546078⟩

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