Structure of an organic charge-transfer salt derived from dibenzotetrathiafulvalene and tetrafluorotetracyanoquinodimethane (DBTTF–TCNQF4). Observation of a high-temperature phase transition

Abstract

The crystal structure of the organic charge-transfer salt DBTTF–TCNQF4 is reported. The structure has been determined by single-crystal x-ray diffraction techniques and has been shown to consist of segregated stacks of donor and acceptor molecules. Within both the donor and acceptor stacks, significant dimerization is observed at room temperature. From the geometries of the DBTTF and TCNQF4 molecules, it is concluded that the charge transfer is complete. The electrostatic contribution to the crystal cohesion for DBTTF–TCNQF4 has been calculated and compares well to those for similar salts of unit charge transfer. It is suggested that the room-temperature structure may well be representative of the low-temperature phase of a system affected by a Peierls instability. Based on diffraction data, a phase transition near 390 K is reported. The driving force for the transition is likely a spin–phonon instability. Crystal data for DBTTF–TCNQF4 are triclinic, space group P1̄; a = 13.159(3) Å, b = 13.703(4) Å, c = 7.533(2) Å, α = 102.89(2)°, β = 105.98(2)°, γ = 63.47(2)°, V = 1160 Å3; with a final R value for the refinement at 298 K of 0.063 based on the 2797 data with F0≳3σ(Fo).

Coupled Protonic and Electronic Conduction in the Molecular Conductor [2-(2-1H-Benzimidazolyl)-1H-benzimidazolium]–TCNQ

“…As expected, the extended p-conjugated system of the monovalent H3BBIM cation formed a uniform p ± p stacking structure. [18] In addition, the side-by-side arrangement of the regular H3BBIM columns formed a channel as a sequence of holes along the c axis (dashed circles in Figure 1 a). These hydrophilic holes were surrounded by one imino nitrogen and three acidic amino protons of H3BBIM , and also contained disordered Cl À ions and H 2 O molecules that originated from the buffer solution.…”

“…[9] To achieve high electrical conducting properties, open-shell molecules generated by charge transfer (CT) interactions were necessary to provide highly mobile electronic carriers and to form a partially filled electronic band structure. [10] Salts, such as (Li ) 0.6 ([15]crown-5)[Ni(dmit) 2 ] 2 and (Li ) x ( [18]crown-6)[Ni(dmit) 2 ] 2 (dmit 2À 2-thioxo-1,3-dithiole-4,5-dithiolate), fulfilled these requirements and exhibited high electrical conductivities through a regular [Ni-(dmit) 2 ] stack. In addition, the crown ether molecules formed regular ionic channel structures, [11,12] and the motion of the Li ions within the ionic channel was coupled with the conduction electrons on the [Ni(dmit) 2 ] column.…”

“…The segregated stacking structure has been reported for the completely ionized (DBTTF )(tetrafluoro-7,7,8,8-tetracyano-p-quinodimethane (F 4 TCNQ) À ) complex. [18] Herein we wish to report on the CT complex of H3BBIM with TCNQ, in which the protonic system of H3BBIM was strongly coupled with the electronic system of TCNQ.…”

Charge‐Transport Properties of F6TNAP‐Based Charge‐Transfer Cocrystals

“…While F 4 TCNQ has often been used as an acceptor in CT cocrystals, its naphthalene analog, 1,3,4,5,7,8‐hexafluoro‐11,11,12,12‐tetracyano‐2,6‐naphthoquinodimethane (F 6 TNAP, also known as F 6 TCNNQ), has been less well studied. As a result of its extended π‐system, F 6 TNAP has a slightly more anodic reduction potential and higher electron affinity than F 4 TCNQ .…”

Syntheses and Crystal Structures of DBTTF Derivatives Substituted Unsymmetrically by Electron Donating Groups: (MeO)2(MDO) DBTTF, (EDO) (MDO) DBTTF and (MeO)2(EDO) DBTTF

“…It is interesting that the hydrogen atom of the benzene ring acts as a hydrogen donor in the hydrogen bonding. Similarly, (7) 0.02805 (7) 0.1 1473 (6) 0.4200 (2) 0.51836 (19) 0.0358 (3) 0.1127 (3) 0.2346 (2) 0.3769 (3) 0.4237 (2) 0.3758 (3) 0.281 5 (3) 0.2822 (3) 0.5606 ( 3) -0.2688 (2) -0.348 l (2) -0.1263 (3) -0.0830 (3) -0.1289 (3) -0.2149 (3) -0.3923 ( (14) 0.1733 (14) O.OOOO ( 14) 0.1366 (13) 0.2868 ( 13) 0.3073 (16) (7) 0.37499 (7) 0.19081 (7) 0.49274 (7) 0.751 3(2) 0.0090 (2) (3) 0.0538 (3) 0.7881 (4) 0.186 (3) -0.0986 (2) -0.0043 (3) -0.1590 (3) -0.001 (3) -0.219(4) -0.131 (4) 0.667(4) 0.809 (3) 0.484 …”