A. I. Kotov

The radical-cation salt (DOEO)4[HgBr4] · TCE: Synthesis, structure and conductivity

Crystals of a new radical-cation salt (DOEO)4[HgBr4] · TCE (I) (DOEO = (1,4-dioxanediyl-2,3-dithio)ethylenedioxotetrathiafulvalene, TCE = 1,1,2-trichloroethane) were synthesized by electrocrystallization method at constant current (i=5×10−6 A/cm2). Crystal structure was studied at room (293 K) and low (30 K) temperatures and was found to consist of the radical-cation layers alternating along the z-axis with tetrahedral HgBr42− anions and TCE molecules. The anion is disordered over three positions at room and over two positions at low temperatures with occupancy factors 87, 11, 2 and 98, 2%, respectively. The poorly occupied positions of the anion are overlapped with positions of the TCE molecule disordered over two equally occupied positions. The DOEO ethylene groups disordered at 293 K were found ordered at 30 K. The conductivity of I exhibits the following peculiarity: in a temperature interval of 120–140 K, the temperature dependence of resistivity has a pronounced maximum.

Two types of charge carrier localization centers in (DOEO)4[HgBr4] · TCE single crystals

Using ESR spectroscopy, it has been found that the additional paramagnetic centers appear in the (DOEO)4[HgBr4] · TCE crystals at temperatures of 5–70 K. The symmetry of their crystal field differs from that observed for charge carriers in a temperature range of 70–300 K. The comparison of the temperature dependences of resistivity with parameters of the ESR spectra makes it possible to assume that the carriers localize at two types of sites differing by the crystalline surrounding at 70 K.

Structures and conductivities of isostructural synthetic metals (DOET)4[Hg2Cl6] and (DOET)4[Hg2Br6]

The structures of organic metals (DOET)4[Hg2Cl6] (1) and (DOET)4[Hg2Br6] (2), where DOET is (1,4-dioxanediyl-2,3-dithio)ethylenedithiotetrathiafulvalene, were established by X-ray diffraction analysis. Compounds 1 and 2 are isostructural, and their crystals have layered structures. The conducting layers formed by the stacked DOET1/2+ cations alternate with the layers of the [Hg2X6]2– anions (X = Cl, Br). The temperature dependence of the conductivity of salt 1 shows a metallic character in the range of 300—4 K. Compound 2 undergoes the metal—semiconductor phase transition (TM—I) at 100 K.

Synthesis, conductivity, and the crystal structure of a new stable metal, β″-(DOEO)2HSeO4 · H2O

AbstractThe stable metal β″-(DOEO)2HSeO4 · H2O I) based on a new donor compound, 3,4-(1,4-dioxanediyl-2,3-dithio)-3′,4′-ethylenedioxo-2,5,2′,5′-tetrathiafulvalene] (DOEO), is synthesized and structurally characterized for the first time. The synthesis is performed by the electrocrystallization technique (direct current density j = 2 × 10−6 A/cm2). The crystals are triclinic, and the unit cell parameters are as follows: a = 5.495(1) Å, b = 9.715(2) Å, c = 16.878(3) Å, α = 83.52(3)°, β = 82.54(3)°, γ = 73.51(3)°, Z = 1, and space group

Studies in the field of organic metals 3. Nonstoichiometric tetraselenotetracene iodides

P\bar 1

Temperature Dependence of Electronic and Magnetic Properties of (DOEO)4[HgBr4]·TCE Single Crystals

. The salt has a layered structure. The DOEO1/2+ radical cation layers are aligned parallel to the ab planes. The HSeO4− · H2O solvated anions are located in channels along the a axis and are disordered over two positions near the center of symmetry (1/2 0 0) with a probability of 50%. The conductivity of the salt is equal to 300–400 Ω−1 cm−1 at room temperature and increases upon cooling to the boiling point of liquid helium (4.2 K) by a factor of 100–200 depending on the sample.

Studies in the field of organic metals

AbstractA new radical cation salt based on 4,5-(1,4-dioxanediyl-2,3-dithio)-4′,5′-ethylenedithiotetrathiafulvalene (DOET) with the photochromic anion [Fe(CN)5NO]2−, namely, (DOET)4[Fe(CN)5 NO]1.25(C6H5Cl)0.75, is synthesized. Single crystals of this salt are studied using X-ray diffraction [a = 10.398(2) Å, b = 11.168(2) Å, c = 18.499(4) Å, α = 103.14(3)°, β = 92.80(3)°, γ = 106.02(3)°, V = 1996.3(7) Å3, space group % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVy0df9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVeLsFr0-vr% 0-vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbGabG% ymayaaraaaaa!3ADD!