Interchain interactions and phase transition in NMeQn(TCNQ)2

doi:10.1016/0038-1098(76)90105-8

Solid State Communications

Volume 19, Issue 11, September 1976, Pages 1091-1094

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Abstract

A sharp non-reversible phase transition is found in the charge transfer salt NMeQn (TCNQ)₂. It is argued that solvent molecules between the chains are responsible for this phase transition, in that, when present they destroy the interchain coupling and lead to effectively decoupled chains in the material. The magnetic and electric properties of both phases are discussed.

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Cited by (7)

Charge orderings and lattice distortions in complex TCNQ salts
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A model for the description of charge orderings and distortions in complex TCNQ salts involving intra- and interchain electron interactions and electron-lattice couplings is investigated. Its thermodynamical properties are analysed in the limit of infinitely strong intramolecular Coulomb repulsion, treating intermolecular interactions within the two-sublattice H-F approximation. Stability conditions for various types of orderings are determined. Site charge ordering and dimerization accompanied by bond charge ordering are found to coexist only in a limited range of parameters diminished by the hopping and the electron-phonon coupling via Coulomb forces. Depending on the value of the latter, interaction phase transitions in the system can be continuous or not. Intermolecular Coulomb interaction stabilizes site charge ordering but it can also essentially enhance transition temperatures and energy gap in dimerized phases. For experimentally reliable values of parameters the energy gaps predicted by the model are in good agreement with those observed in D⁺(TCNQ)⁻₂.
The influence of electron-electron and electron-phonon interactions on electron charge orderings in quasi-one-dimensional systems
1982, Physica B+C
We consider a model for the description of charge orderings and lattice distortions in quasi-one-dimensional narrow-band systems. The Coulomb interactions and the electron-lattice couplings are included in the model and our attention is focused on the effects of electron-phonon couplings via Coulomb forces. It has been found that these interactions can influence the electronic and lattice subsystems in a different way than the electron-phonon couplings usually considered; e.g. (i) they can contribute to the stabilization of the island-type charge ordering and induce tetramerization of the lattice in this state; (ii) they break the particle-hole symmetry and thus lead to temperature dependence of the chemical potential even in the half-filled band case; (iii) they can lead to the appearance of a disorder point at which the charge correlation functions change in character, and to anomalous dilatation of the lattice.
Model for conduction in TCNQ salts
1977, Solid State Communications
We have extended our model for conductivity, σ, and its temperature, T, dependence to a group of molecular conductors including (Qn) (TCNQ)₂, (Adz) (TCNQ)₂ and (Adn) (TCNQ)₂. We have parametrically fit and then quantitatively calculated σ(T) for each of these materials as a product of an activated carrier concentration (600K, 450K, and 350K respectively) and a strongly T-dependent mobility determined by known electron-phonon coupling to the molecular vibrations of TCNQ.
Evidence for intrinsic electrical conduction in the linear metal-chain semiconductor bis(1,2-benzoquinonedioximato)platinum(II), Pt(bqd)<inf>2</inf>
1977, Journal of Solid State Chemistry
The four-electrode dc conductivity of single crystals of the linear metal-chain compound bis(1,2-benzoquinonedioximato)platinum(II), Pt(bqd)₂, measured parallel to the long axis of the crystals, reveals ohmic behavior over the temperature range 77–550°K, and averages to $σ = 3.3 × 10^{−3} Ω^{−1} cm^{−1}$ at room temperature. Unlike the well-characterized Magnus' Green Salt (MGS), Pt(NH₃)₄PtCl₄ ( $σ = 5.5 × 10^{−4} Ω^{−1} cm^{−1})$ , the present compound is found to be an intrinsic, small band gap semiconductor. The PtPt distance of 3.180 Å, the shortest yet observed in Pt(II) glyoximates, was determined by powder X-ray diffraction. The small band gap is related to the unusually high conductivity of Pt(bqd)₂, which is most reasonably interpreted in terms of this short PtPt separation. Preliminary results of polarized single crystal reflectance spectra demonstrating the anisotropic behavior of this compound are presented.
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1,2–BENZOQUINONEDIOXIME (bqdH) AS A VERSATILE LIGAND SYSTEM FOR THE SYNTHESIS OF NEW ONE‐DIMENSIONAL COMPOUNDS
1978, Annals of the New York Academy of Sciences

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Interchain interactions and phase transition in NMeQn(TCNQ)2

Abstract

Phys. Lett.

Mol. Cryst. Liq. Cryst.

Phys. Status Solidi

J. Am. Chem. Soc.

J. Chem. Phys.

Acta Cryst.

Interchain interactions and phase transition in NMeQn(TCNQ)₂