Specific Structural Disorder in an Anion Layer and Its Influence on Conducting Properties of New Crystals of the (BEDT-TTF)4A+[M3+(ox)3]G Family, Where G Is 2-Halopyridine; M Is Cr, Ga; A+ Is [K0.8(H3O)0.2]+

Abstract

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 + [M 3+ (ox) 3 ] 3− G} 2− , where M is Cr, Ga; G is 2-chloropyridine, 2-bromopyridine; and A + is [K 0.8 (H 3 O) 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) 4 A + [M 3+ (ox) 3 ]G family with β"-packing type of conducting BEDT-TTF layers. In contrast to the known superconducting crystals with M 3+ = Fe 3+ and G = 2-chloro-or 2-bromopyridine (T c = 4.0-4.3 K), crystals with Cr 3+ and Ga 3+ 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·H 2 O·0.6 EtOH (5) were obtained. It is a new compound in the family of BEDT-TTF crystals with tris(oxalato)metallate anions.

Double Layer Conducting Salts: (CNB-EDT-TTF)4X, X = ClO4−, ReO4−, and SbF6−; Electrical Transport and Infrared Properties

“…These sample-dependent minima in ρ(T) of ClO 4 − and SbF 6 − samples and the upturn of resistivity upon cooling are ascribed to intrinsic anion disorder effects, leading to progressive localization at low temperatures. This role of disorder is further confirmed by the low temperature behavior approaching a variation linear with the logarithm of temperature, as predicted for an impurity or disorder scattering regime [19] (see inset in Figure 3b) and also similar to the behavior that is observed in other anion disordered layered systems based on the donor BEDT-TTF [20]. It should be also mentioned that attempts to find Shubnikov-de Haas oscillations in the magnetoresistance, at 1.5 K, were unsuccessful for fields up to 16 T, probably due to the disorder present in the crystals.…”

“…Crystals 2019, 9, x FOR PEER REVIEW 6 of 11 systems based on the donor BEDT-TTF [20]. It should be also mentioned that attempts to find Shubnikov-de Haas oscillations in the magnetoresistance, at 1.5 K, were unsuccessful for fields up to 16 T, probably due to the disorder present in the crystals.…”

The Peter Day Series of Magnetic (Super)Conductors

“…In contrast, there are many different solvents that can be found in the hexagonal cavities of the anionic layers. Thus, as it can be seen in Table 1, besides the PhCN molecule used in the first example (35) [3], there are also reported salts with PhNO 2 (3,4), pyridine (py) (1, 2), PhF (19,20), PhCl (17,18), PhBr (15, 16), PhI ( 14), 1,2-PhCl 2 (13), 2-Clpy (29, 30), 3-Clpy (33), 2-Brpy (31, 32), and mixtures of PhCN and py (5)(6)(7)(8)(9)(10)(11)(12) or PhCN with halobenzenes (21)(22)(23)(24)(25)(26)(27) and even with dimethylformamide (dmf) (28), the only non-aromatic solvent used in the β" series with Fe(III) [13].…”

First Molecular Superconductor with the Tris(Oxalato)Aluminate Anion, β″-(BEDT-TTF)4(H3O)Al(C2O4)3·C6H5Br, and Isostructural Tris(Oxalato)Cobaltate and Tris(Oxalato)Ruthenate Radical Cation Salts

“…The most widely studied 4:1 salts in this "Day series" are the β" salts, which crystallise in the monoclinic C2/c space group, of which 32 are superconductors [1,2,. The counter cation (A = H 3 O + /K + /NH 4 + /Rb + ) and the tris(oxalato)metallate metal centre can be changed (M = Fe [1,[7][8][9][10][11][12][13][14][15][16][17][18][19]25], Cr [20][21][22][23][24][25], Co [25], Al [25], Mn [17,26], Ga [24,27,28] Ru [29], Rh [30]), which has a small effect on the electrical properties of the material owing to the change in size of A and M. For example, β"-(BEDT-TTF) 4 (A)M(C 2 O 4 ) 3 •G,…”