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The oxidation of tetraselenatetracene (TSeT) by tetracyanoquinodimethane in the presence of dysprosium(III) tris(hexafluoroacetylacetonate), DyIII(hfac)3, produces black crystals of {TSeT1.5}●+[DyIII(hfac)4]− (1) salt, which combines conducting and magnetic sublattices. It contains one-dimensional stacks composed of partially oxidized TSeT molecules (formal averaged charge is +2/3). Dimers and monomers can be outlined within these stacks with charge and spin density redistribution. The spin triplet state of the dimers is populated above 128 K with an estimated singlet-triplet energy gap of 542 K, whereas spins localized on the monomers show paramagnetic behavior. A semiconducting behavior is observed for 1 with the activation energy of 91 meV (measured by the four-probe technique for an oriented single crystal). The DyIII ions coordinate four hfac− anions in [DyIII(hfac)4]−, providing D2d symmetry. Slow magnetic relaxation is observed for DyIII under an applied static magnetic field of 1000 Oe, and 1 is a single-ion magnet (SIM) with spin reversal barrier Ueff = 40.2 K and magnetic hysteresis at 2 K. Contributions from DyIII and TSeT●+ paramagnetic species are seen in EPR. The DyIII ion rarely manifests EPR signals, but such signal is observed in 1. It appears due to narrowing below 30 K and has g4 = 6.1871 and g5 = 2.1778 at 5.4 K. [ABSTRACT FROM AUTHOR]

Cationic Mn(III) complexes with 3,5‐Hal‐sal2323 (Hal=diCl, diBr, BrCl) ligands containing electroactive TCNQ anions as counterions have been synthesized: [Mn(3,5‐diCl‐sal2323)](TCNQ)2 (1), [Mn(3,5‐diBr‐sal2323)]2(TCNQ)3⋅6CH3CN (2), and [Mn(3,5‐Br,Cl‐sal2323)]2(TCNQ)3⋅6CH3CN (3). The crystal structures, magnetic and conducting properties of the obtained compounds have been investigated. In 1, an incomplete spin transition from the low‐spin (LS) state at 100 K to the high‐spin (HS) state upon heating to 400 K is observed. Isostructural complexes 2 and 3 contain 6 molecules of solvated acetonitrile, which is lost upon heating, accompanied by the crystal structure transformation. As a result, desolvated complexes jump to the HS state. The temperature dependences of resistivity 2 and 3 show resistivity jumps associated with the loss of lattice solvent. [ABSTRACT FROM AUTHOR]

The metal–insulator transition in the organic quasi-two-dimensional metal κ-(BEDT-TTF)2Hg(SCN)2Br at TMI ≈ 90 K has been investigated. The crystal structure changes during this transition from monoclinic above TMI to triclinic below TMI. A theoretical study suggested that this phase transition should be of the metal-to-metal type and brings about a substantial change of the Fermi surface. Apparently, the electronic system in the triclinic phase is unstable toward a Mott insulating state, leading to the growth of the resistance when the temperature drops below TMI ≈ 90 K. The application of external pressure suppresses the Mott transition and restores the metallic electronic structure of the triclinic phase. The observed quantum oscillations of the magnetoresistance are in good agreement with the calculated Fermi surface for the triclinic phase, providing a plausible explanation for the puzzling behavior of κ-(BEDT-TTF)2Hg(SCN)2Br as a function of temperature and pressure around 100 K. The present study points out interesting differences in the structural and physical behaviors of the two room temperature isostructural salts of κ-(BEDT-TTF)2Hg(SCN)2X with X = Br, Cl. [ABSTRACT FROM AUTHOR]

New organic (super)conductors of the β''-(BEDT-TTF)4A+[M3+(C2O4)3]G family, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene; M is Fe; A is the monovalent cation NH4+; G is 2-fluoropyridine (2-FPy) (1); 2,3-difluoropyridine (2,3-DFPy) (2); 2-chloro-3-fluoropyridine (2-Cl-3-FPy) (3); 2,6-dichloropyridine (2,6-DClPy) (4); 2,6-difluoropyridine (2,6-DFPy) (5), have been prepared and their crystal structure and transport properties were studied. All crystals have a layered structure in which the conducting layers of BEDT-TTF radical cations alternate with paramagnetic supramolecular anionic layers {A+[Fe3+(C2O4)3]³-G0}2-.Crystals 1 undergo a structural phase transition from the monoclinic (C2/c) to the triclinic (P1) symmetry in the range 100-150 K, whereas crystals 2-5 have a monoclinic symmetry in the entire range of the X-ray experiment (100-300 K). The alternating current (ac) conductivity of salts 1-4 exhibits metallic behavior down to 1.4 K, whereas the salt 5 demonstrates the onset of a superconducting transition at 3.1 K. The structures and conducting properties of 1-5 are compared with those of the known monoclinic phases of the family containing different monohalopyridines as "guest" solvent molecules G. [ABSTRACT FROM AUTHOR]

Three radical cation salts of BDH-TTP with the paramagnetic [ReF6]2- and diamagnetic [ReO4]- anions have been synthesized: K-(BDH-TTP)4ReF6 (1), κ-(BDH-TTP)4ReF6⋅4.8H2O (2) and pseudo-κ"-(BDH-TTP)3(ReO4)2 (3). The crystal and band structures, as well as the conducting properties of the salts, have been studied. The structures of the three salts are layered and characterized by alternating κ-(1, 2) and κ"-(3) type organic radical cation layers with inorganic anion sheets. Similar to other κ-salts, the conducting layers in the crystals of 1 and 2 are formed by BDH-TTP dimers. The partial population of positions of Re atoms and disorder in the anionic layers of 1-3 are their distinctive features. Compounds 1 and 2 show the metallic character of conductivity down to low temperatures, while 3 is a semiconductor. The ac susceptibility of crystals 1 was investigated in order to test the possible slow relaxation of magnetization associated with the [ReF6]2- anion. [ABSTRACT FROM AUTHOR]

We present herein the synthesis, crystal structure, and electric and magnetic properties of the spin‐crossover salt [Mn(5‐Cl‐sal‐N‐1,5,8,12)]TCNQ1.5⋅2 CH3CN (I), where 5‐Cl‐sal‐N‐1,5,8,12=N,N′‐bis(3‐(2‐oxy‐5‐chlorobenzylideneamino)propyl)‐ethylenediamine, containing distinct conductive and magnetic blocks along with acetonitrile solvent molecules. The MnIII complex with a Schiff‐base ligand, [Mn(5‐Cl‐sal‐N‐1,5,8,12)]+, acts as the magnetic unit, and the π‐electron acceptor 7,7,8,8‐tetracyanoquinodimethane (TCNQ−) is the conducting unit. The title compound (I) exhibits semiconducting behavior with room temperature conductivity σRT≈1×10−4 ohm−1 cm−1 and activation energy Δ ≈0.20 eV. In the temperature range 73–123 K, it experiences a hysteretic phase transition accompanied by a crossover between the low‐spin S=1 and high‐spin S=2 states of MnIII and changes in bond lengths within the MnN4O2 octahedra. The pronounced shrinkage of the basal Mn−N bonds in I at the spin crossover suggests that the dx2-y2 orbital is occupied/deoccupied in this transition. Interestingly, the bromo isomorphic counterpart [Mn(5‐Br‐sal‐N‐1,5,8,12)]TCNQ1.5⋅2 CH3CN (II) of the title compound evidences no spin‐crossover phenomena and remains in the high‐spin state in the temperature range 2–300 K. Comparison of the chloro and bromo compounds allows the thermal and spin‐crossover contributions to the overall variation in bond lengths to be distinguished. The difference in magnetic behavior of these two salts has been ascribed to intermolecular supramolecular effects on the spin transition. Discrete hydrogen bonding exists between cations and cations and anions in both compounds. However, the hydrogen bonding in the crystals of II is much stronger than in I. The relatively close packing arrangement of the [Mn(5‐Br‐sal‐N‐1,5,8,12)]+ cations probably precludes their spin transformation. [ABSTRACT FROM AUTHOR]

New crystals (1-4) of organic conductors based on the radical cation salts of the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with paramagnetic and diamagnetic tris(oxalato)metallate anions {A+[M3+(ox)3]3-G}2-, where M is Cr, Ga; G is 2-chloropyridine, 2-bromopyridine; and A+ is [K0.8(H3O)0.2]+ have been prepared and their crystal structure and transport properties were studied. All crystals belong to the monoclinic group of the (BEDT-TTF)4A+[M3+(ox)3]G family with α"-packing type of conducting BEDT-TTF layers. In contrast to the known superconducting crystals with M3+ = Fe3+ and G = 2-chloro- or 2-bromopyridine (Tc = 4.0-4.3 K), crystals with Cr3+ and Ga3+ ions exhibit metallic properties down to 0.5 K without superconducting transition. Upon cooling these crystals, the incommensurate superstructure appears, which has never been observed before in the numerous β"-salts of the family. In addition, orthorhombic (sp. group Pbca) semiconducting crystals α"-(BEDT-TTF)5[Ga(ox)3]·3.4·H2O·0.6 EtOH (5) were obtained. It is a new compound in the family of BEDT-TTF crystals with tris(oxalato)metallate anions. [ABSTRACT FROM AUTHOR]

Four new superconducting and metallic salts of the family of organic molecular conductors (BEDT-TTF)4AI[FeIII(C2O4)3]G [A = H3O+; G = 2-chloropyridine (1), 2-bromopyridine (2), 3-chloropyridine (3), and 3-bromopyridine (4); BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] have been prepared, and their crystal structures, electronic structures, transport properties, and magnetotransport properties have been studied. All of the crystals obtained belong to the monoclinic group of the family with β''-type packing of the conducting BEDT-TTF layers. Crystals 1 and 2 are superconductors with Tc = 2.4-4.0 and 4.3 K, respectively, and possess structural phase transitions from monoclinic to triclinic symmetry at temperatures of 190-215 K, whereas 3 and 4 retain monoclinic symmetry at 90-300 K and do not show a superconducting transition above 0.5 K. Shubnikov-de Haas (SdH) oscillations were found in crystals of 1, 2, and 4. The structures and conducting properties of 1-4 are compared with those of the known monoclinic phases of the family containing FeIII ions and different monohalobenzenes and pyridine as "guest" solvent molecules (G). [ABSTRACT FROM AUTHOR]

Submicron thin films of Bi2Te2,7Se0,3 solid solution is synthesized by thermal vacuum evaporation. The films are then subjected to after-growth vacuum annealing and characterized using X-ray diffraction and confocal laser microscopy techniques. Electron transport in the synthesized films is studied over the temperature range of 1.4-300 K at magnetic fields up to 8 T. Electron localization due to electron-electron interaction, along with weak anti-localization effect at weak magnetic fields and temperatures below 8 K is observed. The latter effect is commonly encountered in thin films of topological insulators grown by molecular beam epitaxy and has therefore been ascribed to the manifestation of the topological surface states. Finally, phase coherence length is estimated. [ABSTRACT FROM AUTHOR]

New metallic triclinic ( 1) and monoclinic ( 2) crystals of the (BEDT-TTF)4AI[MIII(C2O4)3]G family of organic molecular conductors have been prepared: α-'pseudo-κ'-(BEDT-TTF)4K x(H3O)1- x[GaIII(C2O4)3] ·1,2-C6H4Br2 ( x ≈ 0.45) ( 1) and β″-(BEDT-TTF)4K x(H3O)1- x[GaIII(C2O4)3] ·PhBr ( x ≈ 0.33) ( 2). The triclinic crystals belong to a quite rare type of bilayered radical ion salts and contain alternating BEDT-TTF layers with two distinct packing motifs (α- and 'pseudo-κ'). The monoclinic crystals contain one kind of BEDT-TTF radical cation layers. The crystal structure, transport, and magnetotransport properties of 1 and 2 have been studied. The Shubnikov-de Haas (SdH) oscillations were found in both phases. The structure and properties of 1 and 2 are compared with another similar phase with M = FeIII. [ABSTRACT FROM AUTHOR]

The first molecular superconductor based on BEDT-TTF radical cation salt with the paramagnetic tris(oxalato)ruthenate anion, β′′-(BEDT-TTF)4Kx(H3O)1−x[RuIII(ox)3]C6H5Br (x∼ 0.8), is synthesized and its crystal and electronic structure as well as transport and magnetotransport properties are studied. The single crystals have monoclinic C2/c symmetry and β′′-packing of the conducting BEDT-TTF layer. The samples were found to be superconductors with Tc = 2.8–6.3 K (depending on the sample). Well pronounced Shubnikov–de Haas oscillations are observed in the field range 7–17 T. The Fourier spectrum of the oscillations mainly consists of two frequencies, which correspond to the Fermi surface cross sections 6.3% and 0.85% of the Brillouin zone. The first one with good accuracy corresponds to the calculated cross section 7.5%, the origin of the second one is discussed. Semiconducting orthorhombic phase ‘pseudo-κ’-(BEDT-TTF)4Kx(H3O)1−x[RuIII(ox)3]C6H5CN is also synthesized and studied. [ABSTRACT FROM AUTHOR]

In this study, crystals of the hybrid layered structure, combined with Fe(III) Spin-Crossover (SCO) complexes with metal-dithiolate anionic radicals, and the precursors with nitrate and iodine counterions, are obtained and characterized. [Fe(III)(3-OMe-Sal2trien)][Ni(dmit)2] (1), [Fe(III)(3-OMe-Sal2trien)]NO3·H2O (2), [Fe(III)(3-OMe-Sal2trien)]I (3) (3-OMe-Sal2trien = hexadentate N4O2 Schiff base is the product of the condensation of triethylenetetramine with 3-methoxysalicylaldehyde; H2dmit = 2-thioxo-1,3-dithiole-4,5-dithiol). Bulk SCO transition was not achieved in the range 2.0–350 K for all three compounds. Alternatively, the hybrid system (1) exhibited irreversible segregation into the spatial fractions of Low-Spin (LS) and High-Spin (HS) phases of the ferric moiety, induced by thermal cycling. Fractioning was studied using both SQUID and EPR methods. Magnetic properties of the LS and HS phases were analyzed in the framework of cooperative interactions with anionic sublattice: Anion radical layers Ni(dmit)2 (1), and H-bonded chains with NO3 and I (2,3). LS phase of (1) exhibited unusual quasi-two-dimensional conductivity related to the Arrhenius mechanism in the anion radical layers, ρ||c = 2 × 105 Ohm·cm and ρ⊥c = 7 × 102 Ohm·cm at 293 K. Ground spin state of the insulating HS phase was distinctive by ferromagnetically coupled spin pairs of HS Fe3+, S = 5/2, and metal-dithiolate radicals, S = 1/2. [ABSTRACT FROM AUTHOR]

The transport and superconducting properties of Ba1-xKxFe2As2 single crystals were studied. Both in-plane and out-of-plane resistivity were measured by Montgomery method. The in-plain resistivity temperature dependence was found to be nonlinear with the tendency to saturate at high temperature. We have found that the resistivity anisotropy is almost independent of temperature and lies in the range 10–40 for the studied samples. We explain this result by the extrinsic nature of high out-of-plane resistivity, which may be due to the presence of flat defects along Fe–As layers. This statement is supported by comparatively small effective mass anisotropy, obtained from the upper critical field measurements. [ABSTRACT FROM AUTHOR]

It is shown, that doping by chlorine atoms changes the type of conductivity of Bi2Te3 from p- to n-type as well as the character of conductivity. In the direction perpendicular to the layers plane phonon assisted hopping conductivity is observed. The mechanism of charge transport in Bi2Te3 crystals doped by chlorine atoms is proposed. [ABSTRACT FROM AUTHOR]

The oxidation of tetraselenatetracene (TSeT) by tetracyanoquinodimethane in the presence of dysprosium(III) tris(hexafluoroacetylacetonate), Dy III (hfac) 3 , produces black crystals of {TSeT 1.5 } ●+ [Dy III (hfac) 4 ] - ( 1 ) salt, which combines conducting and magnetic sublattices. It contains one-dimensional stacks composed of partially oxidized TSeT molecules (formal averaged charge is +2/3). Dimers and monomers can be outlined within these stacks with charge and spin density redistribution. The spin triplet state of the dimers is populated above 128 K with an estimated singlet-triplet energy gap of 542 K, whereas spins localized on the monomers show paramagnetic behavior. A semiconducting behavior is observed for 1 with the activation energy of 91 meV (measured by the four-probe technique for an oriented single crystal). The Dy III ions coordinate four hfac - anions in [Dy III (hfac) 4 ] - , providing D 2d symmetry. Slow magnetic relaxation is observed for Dy III under an applied static magnetic field of 1000 Oe, and 1 is a single-ion magnet (SIM) with spin reversal barrier U eff = 40.2 K and magnetic hysteresis at 2 K. Contributions from Dy III and TSeT ●+ paramagnetic species are seen in EPR. The Dy III ion rarely manifests EPR signals, but such signal is observed in 1 . It appears due to narrowing below 30 K and has g 4 = 6.1871 and g 5 = 2.1778 at 5.4 K.

We present herein the synthesis, crystal structure, and electric and magnetic properties of the spin-crossover salt [Mn(5-Cl-sal-N-1,5,8,12)]TCNQ 1.5 ⋅2 CH 3 CN (I), where 5-Cl-sal-N-1,5,8,12=N,N'-bis(3-(2-oxy-5-chlorobenzylideneamino)propyl)-ethylenediamine, containing distinct conductive and magnetic blocks along with acetonitrile solvent molecules. The Mn III complex with a Schiff-base ligand, [Mn(5-Cl-sal-N-1,5,8,12)] + , acts as the magnetic unit, and the π-electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ - ) is the conducting unit. The title compound (I) exhibits semiconducting behavior with room temperature conductivity σ RT ≈1×10 -4  ohm -1  cm -1 and activation energy Δ ≈0.20 eV. In the temperature range 73-123 K, it experiences a hysteretic phase transition accompanied by a crossover between the low-spin S=1 and high-spin S=2 states of Mn III and changes in bond lengths within the MnN 4 O 2 octahedra. The pronounced shrinkage of the basal Mn-N bonds in I at the spin crossover suggests that the d x 2 - y 2 orbital is occupied/deoccupied in this transition. Interestingly, the bromo isomorphic counterpart [Mn(5-Br-sal-N-1,5,8,12)]TCNQ 1.5 ⋅2 CH 3 CN (II) of the title compound evidences no spin-crossover phenomena and remains in the high-spin state in the temperature range 2-300 K. Comparison of the chloro and bromo compounds allows the thermal and spin-crossover contributions to the overall variation in bond lengths to be distinguished. The difference in magnetic behavior of these two salts has been ascribed to intermolecular supramolecular effects on the spin transition. Discrete hydrogen bonding exists between cations and cations and anions in both compounds. However, the hydrogen bonding in the crystals of II is much stronger than in I. The relatively close packing arrangement of the [Mn(5-Br-sal-N-1,5,8,12)] + cations probably precludes their spin transformation., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)