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The C-methylthio derivatives of cobalt bis(dicarbollide) were synthesized by reaction of anhydrous CoCl2 with nido-carborane [7-MeS-7,8-C2B9H11]− and isolated as a mixture of rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− and meso-[1,2′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− isomers. The structures of both isomers were studied using DFT quantum chemical calculations. The most preferable geometry of rotamers and the stabilization energy of C-methylthio derivatives of cobalt bis(dicarbolide) were calculated. The (BEDT-TTF)[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2] salt was prepared and its structure was determined by single crystal X-ray diffraction. The cisoid conformation of the rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− anion is stabilized by short intramolecular CH⋯S hydrogen and BH⋯S chalcogen bonds between the dicarbollide ligands, that is in good agreement with the data of quantum chemical calculations.

The radical-cationic salts based on tetrathiafulvalene derivatives and bis(dicarbollide) transition metal complexes [3,3′-M(1,2-C2B9H11)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.

The first molecular conductors based on bis(1,3-propylenedithio)tetrathiafulvalene and transition metal bis(dicarbollides) (BPDT-TTF)[3,3′-Сr(1,2-C2B9H11)2] (1) and (BPDT-TTF)[3,3′-Сo(1,2-C2B9H11)2] (2) were synthesized and their crystal structures were determined by X-ray analysis. The electric conductivity measurements revealed that these compounds are semiconductors at room temperature.

The synthesis of a radical-cation salt based on a derivative of tetrathiafulvalene, (ET)2[3,3′-Cr(1,2-C2B9H11)2] (ET = bis(ethylenedithio)tetrathiafulvalenium), was accomplished by electrochemical anodic oxidation of ET in the presence of (Me4N)[3,3´-Cr(1,2-C2B9H11)2] in the galvanostatic regime. An electric conductivity σ (293 K) = 7 × 10−3 Ohm−1 cm−1 with semiconductor activation energy Ea ≅ 0.1 eV in the range of 127–300 K was observed. The crystal structure of (ET)2[3,3′-Cr(1,2-C2B9H11)2] was determined by X-ray diffraction at 173 K, revealing the presence of structural tetramers in radical-cation stacks. The magnetic properties of the complex were investigated in the temperature range 1.8–300 K using magnetometry and EPR, showing that the magnetic structure of (ET)2[3,3′-Cr(1,2-C2B9H11)2] consists of two independent magnetic subsystems. Cation radicals form a rectangular magnetic lattice in the ab-plane with significant antiferromagnetic exchange interactions. The chromium bis(dicarbollide) anions are characterized by unusually strong positive zero-field splitting of the Cr(III) ions, which was confirmed by ab initio calculations.

The new molecular conductors based on unconventional tetrathiafulvalene π-donors 4,5-ethylenedithio-4′,5′-(2-oxa-1,3-propylenedithio)tetrathiafulvalene (EOTT) and bis(1,3-propylenedithio)tetrathiafulvalene (BPDT-TTF) and metallacarborane anion [8,8′-Cl2–3,3′-Fe(1,2-C2B9H10)2]− were synthesized and their crystal structures were determined by single crystal X-ray diffraction. The electric conductivity study proved that both compounds (EOTT)2[8,8′-Cl2–3,3′-Fe(1,2-C2B9H10)2] and (BPDT-TTF)2[8,8′-Cl2–3,3′-Fe(1,2-C2B9H10)2] are semiconductors at room temperature.

New radical-cation salts based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) were synthesized: (ЕТ)2[8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2] (1) and (ЕТ)[8,8′-I2-3,3′-Fe(1,2-C2B9H10)2] (2). Their crystal structures were studied by X-ray analysis, electroconducting and magnetic properties were measured in a wide temperature range. Salts (1) and (2) appeared to be the first radical-cation salts with [8,8′-I2-3,3′-Fe(1,2-C2B9H10)2]- and [8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2]- anions, respectively. In the literature [8,8′-I2-3,3′-Fe(1,2-C2B9H10)2]- and [8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2]- anions are presented for the first time. Salts (1) and (2) were found to be paramagnetic. Their room temperature conductivities were 2 and 1·10−6 Ohm−1cm−1, respectively.

The

A new radical cation salt of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iron(III) bis(1,2-dicarbollide) 8,8´-dichloro derivatives, that is (BEDT-TTF)2[8,8´-Cl2-3,3´-Fe-(1,2-C2B9H10)2], was synthesized. Its electroconducting and magnetic characteristics were studied, molecular and crystal structures were determined. The electroconductivity of crystals at room temperature was σ293 ~5 Ω–1 cm–1, which is close to the corresponding value for the salt of cobalt bis(1,2-dicarbollide) dichloro derivative and is considerably higher than the electroconductivity of a similar salt of unsubstituted iron bis(1,2-dicarbollide). The measurements of magnetic susceptibility at 2—300 K showed that this salt is paramagnetic.

The crystal structure of a binuclear mono­carboxyl­ato dirhenium(III) complex with a fulvalene derivative is reported. This compound represents a radical cation salt containing a cluster unit with rhenium–rhenium quadruple bond., The asymmetric unit of the title salt, (C10H8S8)[Re2Br6(CH3COO)]·0.5C2H3Cl3, contains one bis­(ethyl­enedi­thio)­tetra­thia­fulvalene (ET) radical cation, one μ2-acetato-bis­[tri­bromido­rhenate(III)] anion and a 1,1,2-tri­chloro­ethane mol­ecule with half-occupancy disordered about a twofold rotation axis. The tetra­thia­fulvalene fragment adopts an almost planar configuration typical of the ET radical cation. The C atoms of both ethyl­enedi­thio fragments in the cation are disordered over two orientations with occupancy factors 0.65:0.35 and 0.77:0.23. In the anion, six Br atoms and a μ2-acetate ligand form a strongly distorted cubic O2Br6 coordination polyhedron around the Re2 dinuclear centre. In the crystal, centrosymmetrically related ET cations and Re2O2Br6 anions are linked into dimers by π–π stacking inter­actions [centroid-to-centroid distance = 3.826 (8) Å] and by pairs of additional Re⋯Br contacts [3.131 (3) Å], respectively. The dimers are further packed into a three-dimensional network by non-directional inter­ionic electrostatic forces and by C—H⋯Br and C—H⋯S hydrogen bonds. The disordered 1,1,2-tri­chloro­ethane mol­ecules occupy solvent-accessible channels along the b axis.

The new radical cation salts based on transition metal bis(dicarbollides) with dibenzotetrathiafulvalene (DBTTF) donors (DBTTF)[3,3′-Fe(1,2-C2B9H11)2] (1) and (DBTTF)2[3,3′-Cr(1,2-C2B9H11)2] (2) were synthesized and their crystal structures were determined by single crystal X-ray diffractions. The electric conductivity measurements revealed that these compounds are semiconductors at room temperature and the conductivity of (DBTTF)2[3,3′-Cr(1,2-C2B9H11)2] is ~500 times higher than that of its BEDT-TTF analogue.

Radical cation salts based on derivatives of tetrathiafulvalene and sandwiched transition metal bis(dicarbollide) anions are of great interest in the development of new molecular conducting materials. The data on their synthesis, crystal structure, and electrical and magnetic properties were reviewed. The effect of various substituents in the metallacarborane anion on the structure and physical properties of their tetrathiafulvalene-based radical cation salts was analyzed. Relationships between the crystal structure and properties of the tetrathiafulvalene-based radical cation salts containing sandwiched transition metal bis(1,2-dicarbollide) anions are discussed.

Radical cation salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and bis(methylenedithio)tetrathiafulvalene (BMDT-TTF) with the 8,8′-dichloro derivative of cobalt bis(1,2-dicarbollide) (BEDT-TTF)2[8,8′-Cl2-3,3′-Co(1,2-C2B9H10)2] (1) and (BMDT-TTF)4[8,8′-Cl2-3,3′-Co(1,2-C2B9H10)2] (2) were synthesized and their crystal structures and electrocon-ducting properties were determined. The synthesized radical cation salts are semiconductors with the conductivity σ293 = 1.5 and 2.0 Ohm−1 cm−1, respectively. A decrease in the size of the substituent in a series of (BEDT-TTF)2[8,8′-X2-3,3′-Co(1,2-C2B9H10)2] and (BMDT-TTF)4[8,8′-X2-3,3′-Co(1,2-C2B9H10)2] (X = I, Br, Cl) results in the compression of the anion sublattice of the crystal and compaction of the radical cation packing of the conducting layer, which, in turn, increases the conductivity of the crystals.

New radical cation salts (BEDT-TTF)2[anti-7,7′:8,8′-bis(dithio)bis(7,8-dicarba-undecaborate)] and (TMTTF)2[anti-7,7′:8,8′-bis(dithio)bis(7,8-dicarbaundecaborate)] were obtained by electrocrystallization from solution of bis(ortho-carboranyl-1,2-dithiolate)cobalt(II) complex (Me4N)2[Co(1,2-S2C2B10H10)2] and BEDT-TTF or TMTTF, respectively, in acetonitrile – 1,1,2-thrichloroethane. The process is accompanied with the complex demetallation, partial deboronation of the carborane cage and oxidation of dithiolate to cyclic bis(disulfide). X-ray crystal structures and electrical conductivities of the compounds synthesized were determined.

Radical cation salts based on derivatives of tetrathiafulvalene and sandwiched transition metal bis(dicarbollide) anions are of great interest in the development of new molecular conducting materials. The data on their synthesis, crystal structure, and electrical and magnetic properties were reviewed. The effect of various substituents in the metallacarborane anion on the structure and physical properties of their tetrathiafulvalene-based radical cation salts was analyzed. Relationships between the crystal structure and properties of the tetrathiafulvalene-based radical cation salts containing sandwiched transition metal bis(1,2-dicarbollide) anions are discussed.

Molecular conductors based on the 8-hydroxy cobalt bis(dicarbollide) anion, (TMTTF)[8-HO-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] (1), (BMDT-TTF)[8-HO-3,3'-Co(1,2-C2B9H10) (1',2'-C2B9H11)] (2), and (BEDT-TTF)[8-HO-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] (3), were synthesized, and their crystal structures and electrical conductivities were determined. Compounds 2 and 3 are isostructural to the corresponding radical-cation salts of the parent cobalt bis(dicarbollide). All of the radical-cation salts prepared were found to be semiconductors. The relative stability of the rotation conformers of the [8-HO-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-) anion was estimated using DFT/BP86 quantum chemical calculations.

Spectral investigations of the new organic semiconductor of the formula (TMTSF)2[3,3′-Co(1,2-C2B9H11)2], were performed using Raman and quantum chemical simulation methods. The polarized Raman spectra of single crystals of the salt were recorded in the range 150–3100 cm−1. An assignment of the strongest vibrational Raman lines was proposed. The possibility of the presence of two rotamers of the Co anion has been discussed taking into account the DFT calculations and the experimental spectra of the reference material.

The radical cation salts of tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iodo derivatives of cobalt bis(dicarbollide), (TTF)[9,9′,12,12′-I4-3,3′-Co(1,2-C2B9H9)2] and (BEDT-TTF)[9,9′(12′)-I2-3,3′-Co(1,2-C2B9H10)2], respectively, were synthesized and their crystal structures were determined. The introduction of iodine atoms into the lower rim of the dicarbollide ligands, unlike the substitution at the upper rim, leads to insignificant changes in the crystal structure and the conductivity of the radical cation salts compared to the analogous salts based on unsubstituted cobalt bis(dicarbollide).

TTF, TTF-BMDT, TTF-BEDT and TMTSF cation radical salts of cobalt bis(dicarbollide) anion [3,3′-Co(1,2-C2B9H11)2]− and its derivatives are prepared and their crystal structures and electrical conductivities are determined. Some regularities in the crystal structures of the TTF-based radical cation salts prepared are also discussed.

New molecular conductors on the base of 8,8′-diiodo cobalt bis(dicarbollide) anion (TTF)[8,8′-I2-3,3′-Co(1,2-C2B9H10)2] (1), (BMDT-TTF)4[8,8′-I2-3,3′-Co(1,2-C2B9H10)2] (2) and (BEDT-TTF)2[8,8′-I2-3,3′-Co(1,2-C2B9H10)2] (3) were synthesized and their crystal structures and electrical conductivities were determined. All the radical cation salts prepared were found to be semiconductors. Some regularities in the crystal structures of the TTF-based radical cation salts with bis(dicarbollide) complexes of transition metals are discussed.

New radical cation salts (BEDT-TTF)2[3,3′-Co(1,2-C2B9H11)2] (1), (BEDT-TTF)2[8-I-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] (2), (BMDT-TTF)[3,3′-Co(1,2-C2B9H11)2] (3) and (TMTSF)2[3,3′-Fe(1,2-C2B9H11)2] (4) were synthesized and their crystal structures and electrical conductivities were determined. Compound 4 is isostructural to the earlier reported Co analogue. All the radical cation salts synthesized are semiconductors.

New radical cation salts (TMTSF) 2 [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ] ( 1 ), (TTF)[3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ] ( 2 ) and (ET)[3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ] ( 3 ) were synthesized and their crystal structures and electrical conductivities were determined. Compound 1 has layered structure with conducting stacks of the TMTSF cations, whereas compounds 2 and 3 contain separated pairs of fulvalenium cations. Conductivity of crystals 1 at room temperature was found to be 15 Ohm −1 cm −1 , that is the maximum value found for fulvalenium metallacarborane salts.

Three charge-transfer salts of [Ni(dmid)2]− (dmid: 1,3-dithiol-2-one-4,5-dithiolate)—TMTTF[Ni(dmid)2], TTFx[Ni(dmid)2] and ETx[Ni(dmid)2] (TMTTF: tetramethyl-tetrathifulvalene, TTF: tetrathifulvalene, ET: bis(ethylenedithio)-tetrathiafulvalene) are prepared and characterized. The TMTTF[Ni(dmid)2] complex has a structure with mixed packs is formed by cations and anions, which alternate each other with subsequent shift. This compound is semiconductor with the room-temperature conductivity of 2.2 × 10−3 Ω−1 cm−1. The TTFx[Ni(dmid)2] and ETx[Ni(dmid)2] complexes have a highest conductivity: σRT 1.86 and 0.54 Ω−1 cm−1, respectively.

New radical cation salt of bis(ethylenedithio)tetrathiafulvalenium and iron bis(dicarbollide) [BEDT-TTF] 2 [3,3′-Fe(1,2-C 2 B 9 H 11 ) 2 ] ( 1 ) has been synthesized. The crystal structure of 1 has been determined by single-crystal X-ray diffraction method found to be isostructural to the known Co and Cr analogues. The electric conductivity measurement in the range of 110 ÷ 296 К shows that 1 is semiconductor with the room temperature conductivity σ 293 = 1.5 × 10 −2 Ω −1 cm −1 , that is higher than in the Cr analogue and lower than in the Co analogue. The measurement of magnetic susceptibility in the range of 2 ÷ 300 K revealed that 1 is paramagnetic with the absence of significant interactions between the organic radical cations and the paramagnetic anions.

New molecular conductors on the base of 8,8’-dibromo cobalt bis(dicarbollide) anion, (BEDT-TTF)2[8,8’-Br2-3,3’-Co(1,2-C2B9H10)2] (1), and (BEDT-TTF)[8,8’-Br2-3,3’-Co(1,2-C2B9H10)2] (2) were synthesized and their crystal structures and electrical conductivities were determined. Both radical cation salts prepared were found to be semiconductors. The introduction of two bromine atoms in the cobalt bis(dicarbollide) anion produces a strong effect on crystal structure and electrical conductivity of the prepared materials.

Anion-radical salts (ARS) of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and methyl-TCNQ (MTCNQ) of composition [N-(CnH2n+1)-Pz](TCNQ)m and [N-(CnH2n+1)-Pz](MTCNQ)m, with Pz for pirazinium, n=1, 2,⋯5 and m=1, 2 have been synthesized and investigated. The IR absorption spectra of these compounds have been studied at room temperature. For single crystal and pellet samples of the synthesized salts, electric conductivity has been measured in the temperature range of 77 – 300 K, and the basic electrophysical characteristics were determined. The [N-CH3-Pz](TCNQ) compound was revealed to be an organic metal undergoing a metal-dielectric transition when cooled below 120 K, the lowest temperature which has ever been achieved for ARS of TCNQ with close-type cations. The conductivity of [N-(CnH2n+1)-Pz](MTCNQ)m salts has been found to be substantial and comparable with that of analogous TCNQ-based compounds. In this, the above compounds are noticeably distinguished from the ARS with cations based on other nitrogen-containing heterocycles. In crystals of the [N-C2H5-Pz](MTCNQ)2 salt, the existence of a highly quasi-two-dimensional conducting state is expected, despite this being atypical for TCNQ-based ARS.