Preparation,crystal structures and electrical conducting properties of new charge-transfer salts: (ET)2·SO3CF3 and (ET)·ClO4

Two new charge-transfer (CT) salts: (ET)₂·SO₃CF₃ and (ET)·ClO₄ were prepared by chemical oxidation of ET with AgSO₃CF₃ and AgClO₄, respectively. Their crystal structures were determined: monoclinic system, Cc, a=35.239(7) Å, b=6.5440(13) Å, c=14.646(3) Å, β=110.26(3)°, V=3168.5(11) Å³ for (ET)₂·SO₃CF₃; monoclinic system, C2/c, a=15.981(3) Å, b=10.627(2) Å, c=11.495(2) Å, β=120.61(3)°, V=1680.2(6) Å³ for (ET)·ClO₄. Electrical conductivity measurements indicate that (ET)₂·SO₃CF₃ shows semi-conducting behaviour with room temperature conductivity of 0.29 S cm⁻¹, while (ET)·ClO₄ is an insulator.     

Synthesis,electrical properties and crystal structure of a new et-based charge-transfer salt containing binuclear polychloride complex anion

A new charge-transfer salt containing hexachlorodicuprate (II) binuclear polychloride complex counter anions, ET₂Cu₂Cl₆ (ET = BEDT-TTF = bis (ethylenedithio)-tetrathiafulvalene), was prepared. The room-temperature d.c. conductivity and relative resistance temperature dependence of the salt from room temperature down to 77 K along the longest crystal growth direction are reported. The crystal structure is determined by the X-ray diffraction method at room temperature. It belongs to the triclinicpl space group with crystallographic parameters of a = 11.379(4), b= 16.353(4), c = 9.054(4) A, α = 90.33(3), β= 100.69(3), γ= 100.06(2) °, V= 1628(1) A³, Z = 2, d_c = 2.261 g cm⁻³, λ (Mo Kα) = 0.710 69 A, μ = 28.45 cm⁻¹, F₀₀₀ = 1104.00 and final R = 0.043, R_w = 0.057 for 2331 observed reflections. The structure consists of isolated ET stacks and the binuclear polychloride complex dianion (Cu₂Cl₆)²⁻ sheets. In the donor stack, significantly short S···S contacts are observed.     

Investigations in the field of synthetic metals. VI. Synthesis and properties of dibenzotetrathiafulvalene halides

Direct oxidation of dibenzotetrathiafulvalene (DBTTF) by halogens in acetonitrile and nitrobenzene yielded DBTTF₂I₃, DBTTF·I₃, DBTTF·Cl_x (x = 0.7 ? 1), DBTTF·Br_x (x = 0.8 ? 1), and DBTTF·Br_1.2 complexes. Ir-, u.v.-, and e.p.r.-spectra of these compounds have been studied. X-ray data for the complex DBTTF·I₃ are discussed. Conductivities of the above mentioned complexes lie in the range 10^?2 – 10^?4 ohm^?1 cm^?1.     

Crystal structure of the new ternary indide CePt2In2 and the isostructural compounds RPt2In2 (R=La,Pr, Nd)

The title compounds have been synthesized by arc melting of the elemental components and subsequent annealing at 870 K. The crystal structure of CePt₂In₂ was determined from single-crystal X-ray data (R=0.0437 for 1439 |F| values and 62 variables). It represents a new structure type of intermetallic compounds: P2₁/m, mP20, a=10.189(6), b=4.477(4), c=10.226(6) Å, β=117.00(5)°, V=416.1(1) ų, Z=4. Isostructural compounds have been found also for La, Pr, and Nd.     

Crystal and electronic structures and physical properties of two semiconductors: Pb4Sb6Se13 and Pb6Sb6Se17

The title compounds were synthesized by directly reacting the elements in stoichiometric ratios at elevated temperatures. Their crystal structures were determined by single crystal X-ray diffraction. Pb₄Sb₆Se₁₃ crystallizes in the monoclinic space group I2/m with lattice dimensions of a=24.591(1) Å, b=4.0910(2) Å, c=25.212(1) Å, β=93.943(1)°, V=2530.3(2) Å³ (Z=4), while Pb₆Sb₆Se₁₇ crystallizes in the orthorhombic space group P2₁2₁2 with lattice dimensions of a=15.872(4) Å, b=24.061(7) Å, c=4.1382(9) Å, V=1580.4(7) Å³ (Z=2). Electronic structure calculations predicted semiconducting behavior. Temperature dependent electrical conductivity measurements verified this prediction for Pb₄Sb₆Se₁₃.     

Intermolecular interactions in the structure of new molecular semiconductor [Pd(dddt)2]2CF3SO3

An X-ray structural investigation of a new molecular semiconductor, [Pd(dddt)₂]₂CF₃SO₃ (1), where dddt²⁻ is 5,6-dihydro-1,4-dithiin-2,3-dithiolate, is made. Crystal data of 1:a = 6.521(7) Å, b = 8.354(4) Å, c = 16.113(6) Å, α = 87.12(4)°, β = 85.51(6)°, γ = 67.94(7)°, V = 811(1) ų, triclinic, space group P. Crystal structure 1 is characterized by layers of [Pd(dddt)₂]^1/2+ radical cations, with [CF₃SO₃]⁻ anions located between them. In these layers, [Pd(dddt)²]^1/2+ cations form dimers with strongly shortened intermolecular contacts Pd…Pd 3.031 (2) Å. The [CF₃SO₃]⁻ anion in the structure of 1 is disordered.     

Synthesis,crystal structure and thermal behavior of Na4[B10O16(OH)2]·4H2O

New hydrated sodium borate Na₄[B₁₀O₁₆(OH)₂]·4H₂O has been synthesized under mild hydrothermal conditions at 170 °C. The structure was determined by single-crystal X-ray diffraction and further characterized by FT-IR, Raman spectra and DTA-TG. It crystallizes in the monoclinic space group Pc with a unit cell of dimension a = 11.323(2) Å, b = 6.5621(14) Å, c = 12.244(3) Å, α = 90°, β = 91.050(3)°, γ = 90°, V = 909.7(3) Å³, Z = 2. The crystal structure of Na₄[B₁₀O₁₆(OH)₂]·4H₂O consists of Na–O polyhedra and [B₁₀O₁₆(OH)₂]⁴⁻ polyborate anions. Dehydration of this compound occurs in three steps and leads to an amorphous phase which undergoes crystallization.     

The new salt κ-ET2[Hg(SCN)2I]: crystal structure and physical properties

The structure, resistivity and ESR of a new organic conductor κ-ET₂[Hg(SCN)₂I](ET=bis(ethylenedithio) tetrathiafulvalene) are studied. Its main crystallographic parameters are found to be: M-1213.2, a-38.03(1), b= 11.80(1), c = 8.329(9) Å; γ=98.1(2)°; V-3700(2) ų; space group P2₁Ib; Z = 4. It is shown that the radical cations are packed according to the κ-type in the organic sheets, and the anions form polymerized chains. Two different radical cation layers with different amounts of shortened S···S contacts and distinct interaction between anionic and cationic sheets are found. ESR linewidth is found to be 9-11G (300 K), which is substantially narrower than a typical linewidth for ET-based radical cation salts of the κ-type. Based on temperature dependences of the resistance anisotropy and ESR parameters, we suggest that a structure rearrangement with electron localization may take place around 50 K. The comparison of crystal structure and properties of the title compound with other salts of the family ET₂[Hg(SCN)_3−nX_n], where X=Cl, Br, and n = 1.2, is camed out.     

Synthesis,crystal structures and properties of new radical cation salts based on some tetrathiapentalene derivatives with halogenomercurate anions

New radical cation salts of BDH-TTP [2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene], BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] and DTDH-TTP [2-(1,3-dithiol-2-ylidene)-5-(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] with halogenomercurate anions have been prepared. X-ray analysis at 120 K revealed the κ-type arrangement of conducting donor layers in (BDH-TTP)₄Hg₃Br₈ and (BDH-TTP)₄Hg₃Cl₈, and the β-type packing of donor layers in the (BDA-TTP)₄Hg₂Br₆, (BDA-TTP)₆Hg₄I_10.34 and (DTDH-TTP)₆Hg₃Br₉ radical cation salts. The crystals of κ-(BDH-TTP)₄Hg₃Br₈, κ-(BDH-TTP)₄Hg₃Cl₈ and β-(DTDH-TTP)₆Hg₃Br₉ behave as metals down to liquid helium temperatures, the resistivity of BDA-TTP salts shows semiconducting temperature dependence.     

New bisdithiolene metal complex of the 2-thioxo-1,3-dithiole-4,5-dithiolato(dmit) ligand. Preparation,structure and physical properties

The complex HMEDA[Ni(dmit)₂]₂I (HMEDA=Hexamethylethylenediammonium) has been prepared. A single X-ray crystal structure analysis reveals that there are short S⋯S contacts between Ni(dmit)₂ dimmers. The monoclinic system, space group p2/n, has cell dimensions: a=11.710(3) Å, b=22.559(5) Å, c=7.374(2) Å, β=93.000(3)⁰, V=1945.3(8) ų, z=4. Full-matrix least-squares refinement, based on 2989 reflections converged at R=0.0686. The conductivity of this salt at room temperature is 0.1 S cm⁻¹ and it shows semiconducting behavior from 20 to 300 K.     

Neutron structural and vibrational studies of dipotassium selenate tellurate

At room temperature the potassium selenate tellurate K₂SeO₄·Te(OH)₆ (KSeTe) was prepared from water solution of H₆TeO₆ and K₂SeO₄. Its structure has been determined from single crystal using neutron diffraction data. KSeTe is monoclinic with C2/c space group. The unit cell parameters are: a = 11.572(9) Å, b = 6.437(7) Å, c = 13.938(1) Å, β = 106.07(7)°, V = 997.7(1) Å³ and Z = 4. The main feature of this structure is the presence of two different and independent anions (TeO₆⁶⁻ and SeO₄²⁻) in the same unit cell. The structure is built by layers of TeO₆ octahedra altering with planes of SeO₄ tetrahedra linked by a network of hydrogen bonds performed by protons belonging to the OH hydroxide groups. DSC measurements indicate that the crystals of K₂SeO₄·Te(OH)₆ undergo three endothermal peaks at 433, 480 and 495 K.Raman scattering measurements on KSeTe material taken between 300 and 620 K are reported in this paper. The spectra indicate clearly these phase transitions.     

La5M3X (M=Sn,Bi; X=Cl,Br, I): exploring the limit of the Mn5Si3-type hosting lattice

Three new compounds add to the family of the Mn₅Si₃ type host–guest lattice. These are La₅Sn₃X (X=Cl, Br, I) synthesized from stoichiometric mixtures of La, LaX₃ and Sn heated under Ar atmosphere in sealed Ta ampoules at 850–990 °C for 13–62 days. La₅Sn₃X crystallize in the space group P6₃/mcm (No. 193) with lattice parameters a=9.603(1) Å, 9.637(1) Å and 9.673(1) Å; c=6.890(1) Å, 6.931(1) Å and 6.987(1) Å, respectively, for X=Cl, Br and I. Computational analysis using both the extended Hückel and the local density functional methods showed that the Sn and La site acts as electron reservoir, providing electrons to the interstitials as necessary. This gives rise to a metallic behavior. Susceptibility and conductivity measurements confirmed these predictions. The single crystal structure of La₅Bi₃Br is also reported.     

Crystal and electronic structures of the radical cation salt based on EDT-TTF and the photochromic nitroprusside anion, (EDT-TTF)3[Fe(CN)5NO]

A single crystal X-ray diffraction (XRD) study of the radical cation salt (EDT-TTF)₃[Fe(CN)₅NO] has been carried out (a=6.623(3), b=10.487(2), c=15.951(1) Å, α=109.19(1), β=96.30(2), γ=99.15(3)°, V=1017.3(5) Å³, space group P1, Z=1). The crystals have a layered structure with the distinctive feature of the presence of alternating EDT-TTF dimers and monomers in the radical cation stacks. Both the structural features and the calculated HOMO⋯HOMO interaction energies suggest that the strong intradimer interaction is responsible for the charge separation and the semiconducting properties of the salt.     

Crystal structure of the Hg4SiS6 and Hg4SiSe6 compounds

The crystal structures of Hg₄SiS₆ and Hg₄SiSe₆ compounds were investigated using X-ray powder diffraction. These compounds crystallize in the monoclinic Cc space group with the lattice parameters a=1.23020(5), b=0.71031(4), c=1.22791(4) nm, β=109.721(3)° for Hg₄SiS₆ and a=1.28110(4), b=0.74034(4), c=1.27471(1) nm, β=109.605(3)° for Hg₄SiSe₆. Atomic parameters were refined in the isotropic approximation (R_I=0.0571 and R_I=0.0555 for the Hg₄SiS₆ and Hg₄SiSe₆, respectively).     

The Crystal Structure and Phase Transition of Hf2Pt3

The structure of Hf₂Pt₃ has been re-investigated using transmission electron microscopy and Rietveld refinement of neutron powder diffraction data at temperatures up to 1500 °C. This compound does not belong to the MoSi₂ structure type as previously reported, but instead is isostructural with Ti₂Pd₃ and the low-temperature form of Ti₂Ni₃. The crystal structure is orthorhombic (pseudo-tetragonal), Cmcm, Z = 4, with a = 14.653(1) Å, b = 4.8741(3) Å, and c = 4.8671(3) Å at room temperature. The b/c ratio decreases from 1.0014(2) at room temperature to 1.0005(3) at 1500 °C, but the material does not transform to the high-temperature form of Ti₂Ni₃ (I4/mmm) under the conditions studied. The electron diffraction data indicate multiple stacking faults as well as short-range order. On heating above 1630 °C there is a phase transition to a B2-related structure with a ≈ 3.315(1) Å at 1659 °C.     

Thermoelectric properties of the new tellurides SrSc2Te4 and BaSc2Te4 in comparison to BaY2Te4

The two new ternary scandium tellurides SrSc₂Te₄ and BaSc₂Te₄ were prepared by heating the elements at temperatures between 800 °C and 900 °C under vacuum. Both compounds crystallize in the CaFe₂O₄ type, space group Pnma, Z = 4, with lattice dimensions of a = 13.1795(17) Å, b = 4.2323(7) Å, c = 15.367(2) Å, V = 857.2(2) Å³ for SrSc₂Te₄, and a = 13.292(2) Å, b = 4.2694(7) Å, c = 15.523(3) Å, V = 880.9(2) Å³ for BaSc₂Te₄. The structures comprise a three-dimensional network of edge- and corner-sharing ScTe₆ octahedra. The Sr and Ba cations are located in linear channels, surrounded by eight Te atoms forming bicapped trigonal prisms. SrSc₂Te₄ and BaSc₂Te₄ are electron-precise materials exhibiting common oxidation states, Sr²⁺, Ba²⁺, Sc³⁺, and Te²⁻. We calculated the band gaps to be 0.1 eV for SrSc₂Te₄ and 0.2 eV for BaSc₂Te₄. At room temperature, both materials exhibit a high Seebeck coefficient and low electrical conductivity.     

Synthesis,structure of a new acceptor TBA2S6 and preparation,physical properties of ET3S6

A general procedure for the synthesis of the tetrabutylammoium hexasulphide, TBA₂S₆, is first described. The structure of TBA₂S₆ has been determined by X-ray crystallography. Lattice parameters and space group information are as follows: a=15.039(5) Å, b=16.086(5) Å, c=17.078(6) Å, α=β=γ=90.00°, V=4131.5(24) ų, orthorhombic, Pbnb (Z=4). Diffraction data (MoK_α radiation, 2θ_max=50) is collected by Rigaku-AFC6 diffract meter. The structure was solved and refined by direct method and full-matrix least-squares procedures to R-value of 0.0645. The complex ET₃S₆ has been prepared through electrocrystallization ways. The conductivity of this salt at room temperature is 2.3 S cm⁻¹. It shows weak metallic behavior above 240 K. Below this temperature, it becomes a semiconductor. The XPS spectra indicated the presence of three different kinds of S atoms in the salt. The ESR line width is found to be 44.478 G at room temperature.     

Crystal growth and X-ray structure determination of Rb3Bi2I9

The compound Rb₃Bi₂I₉ was synthesized by melting a stoichiometric mixture of RbI and BiI₃ and annealing for 1 month some degrees below the melting temperature of 785±5K; a large single crystal of the title compound has been grown from the melt by directional solidification using the vertical Bridgman-Stockbarger technique. X-ray structure determination of the compound involved single-crystal diffractometry, direct and Patterson methods and least-squares refinement. Rb₃Bi₂I₉ exhibits a new type of crystal structure, crystallizing in the monoclinic space group Pc with unit-cell parameters a=14.690(4), b=8.195(2), c=25.645(6) Å, β=125.39(2)°, V=2517(2) ų, Z=4. The unit-cell of Rb₃Bi₂I₉ has six pseudohexagonal RbI₃ layers which are stacked along the direction near to the normal of the XY plane. Each BiI₆ octahedron shares three corners with three other octahedra to form parallel Bi₂I₉ corrugated layers intersecting Z axis of the structure at an angle near 120°.     

Synthesis and characterization of ɛ-VOPO4 nanosheets for secondary lithium-ion battery cathode

Vanadium (III) phosphate monoclinic VPO₄·H₂O was synthesized hydrothermally. The ?-VOPO₄ nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO₄·H₂O, can reversibly react with more than 1 mol lithium atoms in two steps. Crystal XRD analysis revealed that the structure of the ?-VOPO₄ nanosheets is monoclinic with lattice parameters of α=7.2588(4) Å, b=6.8633(2) Å and c=7.2667(4) Å. The results show that the ?-VOPO₄ nanosheets have a thickness of 200 nm and uniform crystallinity. Electrochemical characterization of the ?-VOPO₄ monoclinic nanosheets reveals that they have good electrochemical properties at high current density, and deliver high initial capacity of 230.3 mA·h/g at a current density of 0.09 mA/cm². Following the first charge cycle, reversible electrochemical lithium extraction/insertion at current density of 0.6 mA/cm² affords a capacity retention rate of 73.6% (2.0–4.3 V window) that is stable for at least 1000 cycles.     

Phase Equilibria in the Sb<Subscript>2</Subscript>Te<Subscript>3</Subscript>–InSb System

The phase diagram of the (Sb₂Te₃)_100?x –InSb _x system was determined based on x-ray diffraction (XRD) analysis, differential thermal analysis (DTA), and microhardness and density measurements. An intermediate compound with composition Sb₂Te₃·2InSb was formed as a result of syntectic reaction, melting incongruently at 553 °C. This compound has tetragonal lattice with unit cell parameters of a = 4.3937 Å, b = 4.2035 Å, c = 3.5433 Å, α = 93.354°, and β = γ = 90°. Sb₂Te₃·(2 + δ)InSb (?1 ≤ δ ≤ +1) and (Sb₂Te₃)_100?x (InSb) _x (90 ≤ x ≤ 100) solid solutions exist in the investigated system, based on the intermediate compound Sb₂Te₃·2InSb and on InSb, respectively. Also, two invariant equilibria exist in the system, with eutectic point coordinates at compositions of x = 60 and x ≈ 85 mol% InSb and eutectic temperatures of T _E = 541 and T _E ≈ 501 °C, respectively.