Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes (original) (raw)
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Electrocrystallization of tetramethyltetrathiafulvalene (TM-TTF) and tetramethyltetraselenafulvalene (TM-TSF) with chlorocyananilate monoanion or/and tris(chlorocyananilato)ferrate(III) in THF/DCM solvent mixtures yielded a salt formulated as [TM-TTF] 4 [K(HClCNAn) 4 ] (1) with the former and π−d hybrid systems, formulated as [TM-TTF] 5 [Fe(ClCNAn) 3 ]•2CH 2 Cl 2 (2) and [TM-TSF] 3 [Fe(ClCNAn) 3 ]•0.5CH 2 Cl•2.5H 2 O (3), respectively, with the latter. Compound 1 shows segregation of TM-TTF donor molecules and K(HClCNAn) 4 anionic clusters in the bc plane. The donor molecules are present as mixed-valence dimers and show a β′ packing arrangement. Compounds 2 and 3 consist of hybrid organic/inorganic structures with no segregation of [Fe(ClCNAn) 3 ] 3− anionic complexes and organic TM-TTF/TM-TSF donors. In the structure of compound 3, TM-TSF dimers are trapped between anilate units of metal complexes of opposite chirality. Furthermore, tetrameric donor motifs and solvent molecules of crystallization complete the structure. Single-crystal conductivity measurements on compounds 1 and 2 show semiconducting behavior with room-temperature conductivity values of 5 × 10 −5 and 2 × 10 −4 10 S cm −1 and activation energies of 1960 and 1900 K, respectively. Under high pressure, compound 2 remains a semiconductor, yet its room-temperature conductivity value strongly increases up to 0.2 S cm −1 at 9.8 GPa.
Synthesis and Electroconductive Properties of Radical Salts Derived from Tetrathiafulvalene Dimers
Journal of Solid State Chemistry, 2002
Palladium(II)-or copper(II)-catalyzed homo-coupling reaction of either trimethylstannyltetrathiafulvalene or tetrathiafulvalenylzinc chloride produces symmetrical bitetrathiafulvalenes (bi-TTFs) in good yields, whereas palladium(0)catalyzed cross-coupling reaction of tetrathiafulvalenylzinc chloride with 4-iodotetrathiafulvalenes leads to the corresponding unsymmetrically substituted bi-TTFs in moderate-to-high yields. The X-ray analysis of bi-TTF derivatives showed planar structures, and the cyclic voltammetry suggested that bi-TTFs have good donor ability comparable to that of BEDT-TTF. The symmetrical bi-TTFs formed the corresponding CT-complexes and cation radical salts. These CT-complexes and radical salts were found to be metallic or semiconducting, reflecting the effect of stoichiometry control in the dimeric TTF system. The X-ray structures of two cation radical salts revealed a unique stacking, and the precise conducting path in BEDO-bi-TTF . ClO 4 was discussed on the basis of MO calculations. # 2002 Elsevier Science (USA)
Russian Journal of General Chemistry, 2019
The radical-cationic salts based on tetrathiafulvalene derivatives and bis(dicarbollide) transition metal complexes [3,3'-M(1,2-C 2 B 9 H 11) 2 ]-(M = Co, Ni, Fe, Cr) are promising for the creation of new molecular conductive materials due to the almost unlimited possibilities of their modification. The relationships between the properties of both components of the cation-radical salts, their crystal structure, and electrical and magnetic properties have been analyzed on the basis of the literature and our own data. The effect of various substituents in metallacarborane anions on the structure and physical properties of their radical cation salts based on tetrathiafulvalene and its derivatives has been revealed. Data on the structure and properties of the radical cation salts with other borate anions are presented for comparison.
Molecular conductors from bis(ethylenedithio)tetrathiafulvalene with tris(oxalato)rhodate
Dalton transactions (Cambridge, England : 2003), 2017
This article reports a family of new radical-cation salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with tris(oxalato)rhodate: three salts with the formula β''-(BEDT-TTF)4[(cation)Rh(C2O4)3]·solvent (solvent = fluorobenzene, chlorobenzene, or bromobenzene) and one with the formula pseudo-κ-(BEDT-TTF)4[(NH4)Rh(C2O4)3]·benzonitrile. We report here the syntheses, crystal structures, electrical properties and Raman spectroscopy of these new molecular conductors. The bromobenzene salt shows a decrease in resistivity below 2.5 K indicative of a superconducting transition and a Shubnikov-de Haas oscillation with a frequency of 232 T and effective mass m* of 1.27me.
Journal of Organometallic Chemistry, 2020
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Journal of Materials Chemistry, 1998
Lithiation of 4,5-bis(methylsulfanyl )-TTF 9, 4,5-(ethylenedisulfanyl)-TTF 10, 4,5-dimethyl-TTF 11 and 4,5,5∞-trimethyl-TTF 12 (TTF=tetrathiafulvalene) followed by reaction with methyl isothiocyanate affords the corresponding (N-methylthiocarbamoyl)-TTF derivatives 14-17, respectively, in 54-70% yields. These new TTF derivatives display a broad intramolecular charge-transfer band in their UV-VIS spectra arising from conjugation between the donor TTF ring and the acceptor Nmethylthiocarbamoyl moiety. Steric hindrance between the adjacent N-methylthiocarbamoyl and methyl substituents in 17 causes a marked hyposchromic shift in this band (l max 395 nm) compared to compounds 14-16 (l max 435-467 nm). Consistent with the electron-withdrawing properties of the N-methylthiocarbamoyl substituent, its attachment to the TTF ring raises slightly the oxidation potential of the system. Charge transfer complexes of these donors and (N-methylthiocarbamoyl)-TTF 2 with 7,7,8,8tetracyano-p-quinodimethane (TCNQ) and salts with bromide anions are reported, some of which have high room temperature conductivity values. The X-ray crystal structures are presented for 16, 17 and the salts 2·Br, 14·TCNQ and 2 ·20. The structure of 16 comprises orthogonal dimers (kappa packing) while in the structure of 17 individual molecules are orthogonal to each other. There is weak intermolecular hydrogen bonding in both 16 and 17. In the structure of 2·Br, the radical cations 2+· are almost planar and they form an infinite stair-like stack of dimers, with bromide anions situated between the stacks, and linked with the cation by a strong N-H,Br bond. The structure of 14·TCNQ comprises mixed ,DDAADD, stacks; the Nmethylthiocarbamoyl group engages in an interstack N-H,N bond with a TCNQ anion. Analysis of the bond lengths in the structure suggests that there is partial charge transfer from 14 to TCNQ. In the structure of (17) 2 ·20 molecules form mixed ,DDADDA, stacks and analysis of bond lengths suggests that there is only a small degree of charge transfer from donor to acceptor. The geometries of compounds 2, 14, 16, 17 were optimised using the PM3 semi-empirical method and the results compare favourably with the X-ray structural data.
Crystals
New radical-cation salts based on tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenefulvalene (TMsTSF) with metallacarborane anions (TMTTF)[3,3′-Cr(1,2-C2B9H11)2], (TMTTF)[3,3′-Fe(1,2-C2B9H11)2], and (TMTSF)2[3,3′-Cr(1,2-C2B9H11)2] were synthesized by electrocrystallization. Their crystal structures were determined by single crystal X-ray diffraction, and their electrophysical properties in a wide temperature range were studied. The first two salts are dielectrics, while the third one is a narrow-gap semiconductor: σRT = 5 × 10−3 Ohm−1cm−1; Ea ≈ 0.04 eV (aprox. 320 cm−1).
Journal of Materials Chemistry, 2001
Cl(pBIB) (ET~bis(ethylenedithio)tetrathiafulvalene, pBIB~p-bis(iodoethynyl)benzene) salt is a unique organic metal containing supramolecular assemblies based on the pBIB molecule and the Cl anion. We newly prepared chloride and bromide ET cation radical salts with the use of di-and tetra-substituted pBIB derivatives: 1,4-difluoro-2,5-bis(iodoethynyl)benzene (DFBIB), 1,2,4,5-tetrafluoro-3,6-bis(iodoethynyl)benzene (TFBIB), 1,4-bis(iodoethynyl)-2,5-dimethylbenzene (BIDMB), and p-bis(iodoethynyl)benzene-d 4 (pBIB-d 4). The effect of substitution has been studied by X-ray structure analyses, tight-binding band calculations, and resistivity measurements. Halide ion replacement as well as deuterium-and difluoro-substitutions do not change the fundamental crystal structure and the metallic behavior, but affect the anisotropy of the electronic structure. On the other hand, the tetrafluoro-and dimethyl-substitutions induce different donor arrangements that lead to semiconducting behaviors.
Crystal Growth & Design, 2017
The electrocrystallization from dichloromethane or tetrahydrofuran solutions of the dissymmetrical bis(ethylenedithio)tetrathiafulvalene (ET) derivative cyanobenzene−ethylenedithio−tetrathiafulvalene (CNB-EDT-TTF) in the presence of perchlorate anion ClO 4 − affords two different polymorphs of salts with 4:1 stoichiometry, a previously described triclinic phase β″ T-(CNB-EDT-TTF) 4 ClO 4 (1a), and a new monoclinic phase β″ M-(CNB-EDT-TTF) 4 ClO 4 , (1b), as well as a compound with 1:1 stoichiometry, (CNB-EDT-TTF)ClO 4 (2), depending on the solvent and crystallization conditions. The special conditions necessary for the growth of the unusual 4:1 salts, requiring low current densities to oxidize the donors and subsequent slow diffusion controlled association processes, are discussed. Both 4:1 polymorphs present a bilayer structure of the donors induced by head-to-head C−N•••H pairing interactions associated with a combination of R 2 2 (10) and R 2 4 (10) synthons between donors in nearby layers. These polymorphs share the same β″-type donor packing pattern in the layers, but the anions which are disordered over two possible orientations in the triclinic phase appear ordered in the monoclinic one, with a doubling of the interlayer cell axis, due to an alternation of the orientation of the molecules in the bilayers. The 1:1 salt 2 presents a crystal structure with dimerized donors stacks. The donor molecules in nearby stacks are connected by a helical network of C−N•••H pairing interactions. A new polymorph of the neutral donor β-CNB-EDT-TTF (3) is also described.