From Quasi-One-Dimensional Conductors Based on TCNQ Salts to the First Quasi-Two-Dimensional Superconductors at Ambient Pressure Based on BEDT-TTF Triiodides

Yagubskii, Eduard B.

doi:10.1007/978-94-007-1027-6_3

Cited by 5 publications

(5 citation statements)

References 46 publications

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“…The conductivity in the plane ab is practically isotropic (σ ∥TCNQ stacks /σ ⊥TCNQ stacks ≈ 2.0 at 300 K). Hence the obtained compound is a quasi-two-dimensional semiconductor (ρ ⊥ /ρ ∥ ≈ 1.3 × 10 3 ; inset, Figure ) in contrast to the majority of known TCNQ salts, which are generally the quasi-one-dimensional conductors . The averaged value of the in-plane conductivity at room temperature is 5.2 × 10 –2 Ω –1 cm –1 .…”

Section: Results and Discussionmentioning

confidence: 92%

“…So far, the basic class of such materials was mainly represented by the quasi-two-dimensional (super)conductors based on the radical cation salts of bis(ethylenedithio)tetrathiafulvalene and its derivatives with paramagnetic metal complex anions of different nature. − It is of a considerable interest to use the octahedral cation complexes of Fe(II) and Fe(III), showing reversible spin-crossover (SCO) between high-spin (HS) and low-spin (LS) states of the metal ion, as a magnetic subsystem in combination with an anion-conducting subsystem . The conducting sublattice of such hybrid materials could be represented by the radical anion subsystem based on [M(dmit) 2 ] •δ− complexes (M = Ni, Pd, Pt; dmit = 4,5-dithiolato-1,3-dithiole-2-thione; 0 < δ < 1) and/or 7,7,8,8,-tetracyanoquinodimethane ((TCNQ) •δ− , 0 < δ < 1) in a fractional oxidation or reduction state, respectively. The SCO induced by temperature, pressure, or light irradiation is accompanied by the changes in the coordination environment of the metal ion .…”

Section: Introductionmentioning

confidence: 99%

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The Conducting Spin-Crossover Compound Combining Fe(II) Cation Complex with TCNQ in a Fractional Reduction State

et al. 2016

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The radical anion salt [Fe{HC(pz)3}2](TCNQ)3 demonstrates conductivity and spin-crossover (SCO) transition associated with Fe(II) complex cation subsystem. It was synthesized and structurally characterized at temperatures 100, 300, 400, and 450 K. The compound demonstrates unusual for 7,7,8,8,-tetracyanoquinodimethane (TCNQ)-based salts quasi-two-dimensional conductivity. Pronounced changes of the in-plane direct-current resistivity and intensity of the electron paramagnetic resonance (EPR) signal, originated from TCNQ subsystem, precede the SCO transition at the midpoint T* = 445 K. The boltzmannian growth of the total magnetic response and structural changes in the vicinity of T* uniquely show that half [Fe{HC(pz)3}2] cations exist in high-spin state. Robust broadening of the EPR signal triggered by the SCO transition is interpreted in terms of cross relaxation between the TCNQ and Fe(II) spin subsystems.

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Section: Results and Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The Conducting Spin-Crossover Compound Combining Fe(II) Cation Complex with TCNQ in a Fractional Reduction State

et al. 2016

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“…The trend is associated with the use of the octahedral cation complexes of Fe(II), Fe(III) and Co(II), showing reversible spin-crossover (SCO) between high-spin (HS) and low-spin (LS) states of the metal ion, in combination with the radical anion conducting subsystems [16,17]. The latter could be represented by the systems based on [M(dmit) 2 ] δ− complexes (M = Ni, Pd, Pt; dmit = 4,5-dithiolato-1,3-dithiole-2-thione; 0 < δ < 1) [18] and/or 7,7,8,8,-tetracyanoquinodimethane ((TCNQ) δ− , 0 < δ < 1) [19][20][21][22][23]. The availability of fractional oxidation ([M(dmit) 2 ] δ− ) or reduction states ((TCNQ) δ− ) is a necessary condition for the emergence of high conductivity in these systems.…”

Section: Introductionmentioning

confidence: 99%

The Highly Conducting Spin-Crossover Compound Combining Fe(III) Cation Complex with TCNQ in a Fractional Reduction State. Synthesis, Structure, Electric and Magnetic Properties

et al. 2017

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Three systems [Fe(III)(sal 2 -trien)](TCNQ) n ·X (n = 1, 2, X = MeOH, CH 3 CN, H 2 O) showing spin-crossover transition, conductivity and ferromagnetic coupling were synthesized and studied by X-ray diffraction, Montgomery method for resistivity, SQUID magnetometry and X-band EPR. Spin-spin interactions between local magnetic moments of Fe(III) ions and electron spins of organic TCNQ network were discovered and discussed within the framework of intermolecular superexchange coupling.

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“…Some of the π-RAs isolated in the form of thermally stable salts have found applications in the field of molecule-based functional materials as charge and/or spin carriers. They are represented mainly by derivatives of cyanocarbons, such as TCNE and TCNQ, (semi)quinones, and nitrogen heterocycles, such as azines. − …”

Section: Introductionmentioning

confidence: 99%

Interaction of 1,2,5-Chalcogenadiazole Derivatives with Thiophenolate: Hypercoordination with Formation of Interchalcogen Bond versus Reduction to Radical Anion

et al. 2011

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According to the DFT calculations, [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (4), [1,2,5]selenadiazolo[3,4-c][1,2,5]thiadiazole (5), 3,4-dicyano-1,2,5-thiadiazole (6), and 3,4-dicyano-1,2,5-selenadiazole (7) have nearly the same positive electron affinity (EA). Under the CV conditions they readily produce long-lived π-delocalized radical anions (π-RAs) characterized by EPR. Whereas 4 and 5 were chemically reduced into the π-RAs with thiophenolate (PhS(-)), 6 did not react and 7 formed a product of hypercoordination at the Se center (9) isolated in the form of the thermally stable salt [K(18-crown-6)][9] (10). The latter type of reactivity has never been observed previously for any 1,2,5-chalcogenadiazole derivatives. The X-ray structure of salt 10 revealed that the Se-S distance in the anion 9 (2.722 Å) is ca. 0.5 Å longer than the sum of the covalent radii of these atoms but ca. 1 Å shorter than the sum of their van der Waals radii. According to the QTAIM and NBO analysis, the Se-S bond in 9 can be considered a donor-acceptor bond whose formation leads to transfer of ca. 40% of negative charge from PhS(-) onto the heterocycle. For various PhS(-)/1,2,5-chalcogenadiazole reaction systems, thermodynamics and kinetics were theoretically studied to rationalize the interchalcogen hypercoordination vs reduction to π-RA dichotomy. It is predicted that interaction between PhS(-) and 3,4-dicyano-1,2,5-telluradiazole (12), whose EA slightly exceeds that of 6 and 7, will lead to hypercoordinate anion (17) with the interchalcogen Te-S bond being stronger than the Se-S bond observed in anion 9.

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From Quasi-One-Dimensional Conductors Based on TCNQ Salts to the First Quasi-Two-Dimensional Superconductors at Ambient Pressure Based on BEDT-TTF Triiodides

Cited by 5 publications

References 46 publications

The Conducting Spin-Crossover Compound Combining Fe(II) Cation Complex with TCNQ in a Fractional Reduction State

The Conducting Spin-Crossover Compound Combining Fe(II) Cation Complex with TCNQ in a Fractional Reduction State

The Highly Conducting Spin-Crossover Compound Combining Fe(III) Cation Complex with TCNQ in a Fractional Reduction State. Synthesis, Structure, Electric and Magnetic Properties

Interaction of 1,2,5-Chalcogenadiazole Derivatives with Thiophenolate: Hypercoordination with Formation of Interchalcogen Bond versus Reduction to Radical Anion

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