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Three new radical cation salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with the magnetic metal complex anion [ReCl], viz., β-(BEDT-TTF)[ReCl] ( 1), α´-(BEDT TTF)[ReCl]•(DCE) ( 2), and δ-(BEDT-TTF)[ReCl]•(CB) ( 3) (DCE is dichloroethane, CB is chlorobenzene), were synthesized for the first time. The X-ray diffraction analyses of the obtained crystals at room and low temperatures showed that all of them had the sandwich structure characteristic of alternating anionic and cationic layers, which is characteristic of conducting radical cation salts. The structural phase transition accompanied by unit cell tripling and decreasing the symmetry from monoclinic to triclinic in the low-temperature phase occurs in the crystals of salt 2. The transition is related to modulated displacements of both [ReCl] anions and BEDT-TTF radical cations. A specific feature of the crystals of salt 3 is a strong positional disorder in the anionic layer, which is expressed as a random distribution of [ReCl] anions and CB solvent molecules in a ratio of 2 : 1 along the channels in the ordered cationic framework. [ABSTRACT FROM AUTHOR]

New radical cation salts based on 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP), viz., κ-(BDH-TTP)CuCl·(HO) ( 1) and κ-(BDH-TTP)[CuCl]· ·(HO) ( 2), were synthesized and structurally characterized. Single crystals were prepared by the electrochemical oxidation of BDH-TTP under galvanostatic conditions. The X-ray diffraction study showed that the salts have layered structures characterized by the presence of κ-type BDH-TTP conducting layers. These layers alternate with the complex anions composed of [CuCl] units and water molecules. Both salts exhibit the temperature dependence of the metallic conductivity down to 4.2 K. Spin-spin antiferromagnetic correlations in the Cu subsystem were observed in the crystals of 2. [ABSTRACT FROM AUTHOR]

Abstract: The first polymorph, κ″-(ET)2Cu[N(CN)2]Cl, of the well known Mott insulator κ-(ET)2Cu[N(CN)2]Cl has been prepared and its crystal and electronic structures have been examined. The polymorph has monoclinic symmetry in contrast with the orthorhombic one of the isostructural κ-salts of the family (ET)2Cu[N(CN)2]X (X=Cl, Br, I). The monoclinic phase exhibits a layered structure in which the conducting layers are packed in a κ-type arrangement and the anion sheets consist of polymeric zigzag chains formed by Cu[N(CN)2]Cl units. The main structural differences with the orthorhombic κ-salts are that the anion sheets are disordered and the ET molecules are less planar. The new polymorph shows metallic type resistivity down to 4.2K. [Copyright &y& Elsevier]

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]