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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]

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]

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 first radical cation salts based on BETS and ET π-donors with dicyanamide-cuprate counterions were synthesized. Their crystal and electronic structures as well as transport and magnetic properties were studied. • First radical cation salts with paramagnetic dicyanamidocuprate (Cu2+ and Cu1+, Cu2+) anions. • Semiconductor – semiconductor phase transition with a large hysteresis. • Effect of pressure on metal-insulator and semiconductor-semiconductor transitions. • First order phase transition associated with charge distribution. Electrocrystallization of bis(ethylenedithio)tetraselenafulvalene (BETS) and bis(ethylenedithio)tetrathiafulvalene (ET) in the presence of an electrolyte (Ph 4 P)[Cu(dca)] 3 ⋅H 2 O [(dca) = N(CN) 2 ] has been studied using different solvents. A new organic metal (BETS) 2 Cu(dca) 3 (1), and the first radical cation salt with 3D dicyanamidocuprate anion, incorporating both diamagnetic Cu1+ and paramagnetic Cu2+atoms, (ET) 2 Cu 1.8 (dca) 4 (2) have been obtained. Crystal structure, conducting properties of both salts, as well as the electronic structure of 2 and its structural analog (ET) 2 CuMn(dca) 4 (3) were analysed. The salts 1 and 2 have layered structures. In contrast to the BETS radical cation salt 1 , complex 2 is characterized by the presence of a 3D polymeric anion built into the ET radical cation layers. At ambient pressure, the resistance of the crystals 1 shows semimetal behaviour down to 30 K. Below 30 K, the resistance sharply increases and the sample becomes insulating. The application of a pressure of about 3 kbar suppresses the metal-insulator transition. The salt 2 undergoes a semiconductor I - semiconductor II phase transition, which is manifested by a jump in the resistance and a hysteresis in the R(T) curves in a very large temperature range (185 – 250 K). The phase transition is accompanied by changes in the charge state of the ET molecules, and notable structure changes in the anion layer, especially in the environment of Cu2+. For the salt 3 the calculated selfconsistent charges show upon cooling a sharp increase of charge order between 291 K and 285 K. [ABSTRACT FROM AUTHOR]