Crystal structure of (DEPA) (TCNQ)4 and stoichiometric variation of some related TCNQ salts

Ashwell, Geoffrey J.; Allen, J. G.; Goodings, E. P.; Kennedy, Deirdre A.; Nowell, Ian W.

doi:10.1002/pssa.2210750242

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…In the 1970s and 1980s, Ashwell investigated similar (dication)(TCNQ) x series using dipyridinium salts, as indicated in Scheme . − The most remarkable salt among those studied is (DEPE)(TCNQ) 4 (DEPE = 1,2-di( N -ethyl-4-pyridinium)ethylene). The conductivity of (DEPE)(TCNQ) 4 is 150–2200 S cm –1 at room temperature, and it shows metallic behavior down to 30 mK .…”

Section: Introductionmentioning

confidence: 99%

Structural and Physical Properties of a Series of 7,7,8,8-Tetracyanoquinodimethane Salts with Dications Bearing Two Terminal Pyridinium Rings

Kubota¹,

Takahashi²,

Harada³

et al. 2014

Crystal Growth & Design

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A series of radical anion salts composed of 7,7,8,8tetracyanoquinodimethane (TCNQ) and dications with -C n H 2n -(n = 1−6) chains between two pyridinium rings are synthesized. The dication and TCNQ formed either 1:4 or 1:3 stoichiometries with no correlation between the composition and n. The 1:4 stoichiometry salts were obtained when n = 1, 3, 4, 5, 6, where TCNQ formed a one-dimensional column with either dimerization or tetramerization. In these salts, the individual dication length varied considerably, but the effective dication length (the distance between two adjacent dications in the lattice) was independent of n. For n = 1, solvent molecules were involved. However, the 1:4 stoichiometry could not be formed for n = 2 since an appropriate effective dication length could not be attained. The 1:3 stoichiometry salts were obtained when n = 2 and 6. In both crystals, TCNQ assembled into a trimer. For both stoichiometries, the crystals were moderately conducting (resistivity at room temperature: 10 1 −10 4 Ω cm) and had a semiconducting temperature dependence, demonstrating nonuniform TCNQ stacking. The charge-localized feature was revealed by the magnetic properties. All of the salts showed antiferromagnetic interactions between the localized spins with varying exchange interaction parameters, reflecting the structural features.

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Section: Introductionmentioning

confidence: 99%

Structural and Physical Properties of a Series of 7,7,8,8-Tetracyanoquinodimethane Salts with Dications Bearing Two Terminal Pyridinium Rings

Kubota¹,

Takahashi²,

Harada³

et al. 2014

Crystal Growth & Design

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Electrical, Magnetic, and Structural Characterisation of the 1:2 and 1:3 TCNQ Salts of 1,2-Bis(4-Pyridinium)Ethane

Ashwell

Allen

Cross

et al. 1983

Phys. Stat. Sol. (a)

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The 1:2 simple salt, [1,2‐bis(4‐pyridinium)ethane]2+ (7,7,8,8‐tetracya‐no‐p‐quinodimethanide) 22−, (DHPA)(TCNQ)2, is monoclinic, space group C2/c, with a = 29.517(15), b = 7.426(5), c = 13.528(6) Å, β= 93.98(5)°, U = 2958 Å3, Dm, = 1.34 Mg m−3, Z = 4, De, = 1.34 Mg m−3. The structure is solved by direct methods and refined to a final R of 0.042 for 1884 observed reflections. The TCNQ's are arranged in sheets, parallel to the bc‐plane, the sheets being interleaved along a by the DHPA dications. Within the stoichiometric unit the TCNQ's overlap in an exocyclic bond to qoinonoid ring manner, with a mean intermolecular spacing of 3.04 Å, whereas between diads there is no direct overlap. (DHPA)(TCNQ)2, is a diamagnetic insulator with χm, = −3.2 × 10−4e.m.u. mol−1 and σ300K = 1 × 10−7S cm−1. The 1:3 complex salt, (DHPA) (TCNQ)2, is similarly monoclinic, space group P21/c, with a = 12.91(3), b = 3.93(3), c = 27.62(3) Å, β = = 109.9(3) °, U = 1318 Å3, Dm = 1.35 Mg m−3, Z = 4/3, Dc = 1.34 Mg m−3. (DHPA) (TCNQ) 3 is a small band gap semiconductor with d300K= 10 S cm−1. The magnetic susceptibility shows Curia‐Weiss behaviour.

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Electrical, magnetic, and structural characterisation of [1,2-Bis(1-ethyl-4-pyridinium)ethane]2+ (7,7,8,8-tetracyano-p-quinodimethanide)42−

Ashwell¹,

Nowell²

1984

Phys. Stat. Sol. (a)

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The 1:4 complex salt, [1,2‐bis(1‐ethyl–4‐pyridinium)ethane]2+(7,7,8,8‐tetracyano‐pquinodime‐thanide) 42−, (DEPA) (TCNQ)4, is monoclinic, space group P2J/c, with a = 15.21(1), b = 25.97(2), c = 7.77(1) Å, β = 116.3(1)°, U = 2751 Å3, Dm = 1.30 Mg m−3, Z = 2, Dc = 1.28 Mg m−3. The structure is solved by direct methods and refined to a final R of 0.065 for 2036 observed reflections. The mean lengths of the chemically similar bonds of the TCNQ moieties indicate partial electron localisation with 0.3e on TCNQ(A) and 0.6e on TCNQ(B). (DEPA) (TCNQ)4 is a small band gap semiconductor. Along b, the electrical conductivity varies as σ = σ0 exp (−Ea/kT) where σ300K = 1 × 10−3 S cm−1 end Ea = 0.29(4) eV above 300 K and 0.20(2) eV below. The magnetic susceptibility shows singlet‐triplet behaviour with a singlet‐triplet separation of 0.017 eV.

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Crystal structure of (DEPA) (TCNQ)4 and stoichiometric variation of some related TCNQ salts

Cited by 4 publications

References 7 publications

Structural and Physical Properties of a Series of 7,7,8,8-Tetracyanoquinodimethane Salts with Dications Bearing Two Terminal Pyridinium Rings

Structural and Physical Properties of a Series of 7,7,8,8-Tetracyanoquinodimethane Salts with Dications Bearing Two Terminal Pyridinium Rings

Electrical, Magnetic, and Structural Characterisation of the 1:2 and 1:3 TCNQ Salts of 1,2-Bis(4-Pyridinium)Ethane

Electrical, magnetic, and structural characterisation of [1,2-Bis(1-ethyl-4-pyridinium)ethane]2+ (7,7,8,8-tetracyano-p-quinodimethanide)42−

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