E. B. Yagubskii

Resistance and magnetoresistance anomaly in a new stable organic metal (ET)2TlHg(SCN)4

Abstract A new organic metal (ET) 2 TlHg(SCN) 4 has been synthesized. The X-ray study shows the compound to be isostructural to (ET) 2 MHg(SCN) 4 salts with M = K, NH 4 and Rb. The resistance and magnetoresistance measurements show anomalous behaviour at low temperature which may be attributed to spin-density-wave instability. Shubnikov-de Haas oscillations have also been observed at low temperature.

Band structure and Fermi surface of the (BEDT-TTF)4M[Fe(CN)5NO]2 (M=Na, K, Rb,…) molecular metals containing the photochromic nitroprusside anion

Abstract Tight-binding band structure calculations for the room temperature crystal structure of the new family of (BEDT-TTF)4M[Fe(CN)5NO]2 (M=Na, K, Rb, NH4, Cs, Tl) salts are reported. It is shown that the Fermi surface of these salts contains two contributions: (a) a strongly warped non-nested open part and (b) a contribution which can be open or closed depending on minor changes in the donor–donor interactions which in either case exhibits well-nested portions. Because of these features, the pressure dependence of both the magnetoresistance measurements and the possible occurrence of density wave instabilities would be very interesting to study.

Molecular metals based on radical cation salts of ET and some its analogues with the photochromic nitroprusside anion, [Fe(CN)5NO]2-

Abstract A series of electroconducting radical cation salts based on ET, BEDO and EDT with the photochromic nitroprusside anion has been synthesized. Their crystal structures and transport properties have been studied. The salts of the (ET) 4 M[Fe(CN) 5 NO] 2 (M=Na,K,NH 4 ,Tl,Rb,Cs) composition are isostructural and exhibit metallic behaviour down to helium temperatures.

EELS, XPS and IR study of C60·2S8 compound

Abstract Results from electron energy loss, X-ray photoelectron, and infrared spectroscopies are ptesented for the C 60 ·2S 8 compound. As one goes from C 60 to C 60 ·2S 8 , binding energy decreases by 0.5 eV, and ( σ + π ) plasmon energy decreases by 1.2 eV. Arguments for charge redistribution are performed.

[Ni(dddt)2]3(HSO4)2, the first metal among the M(ddt)2 salts

Abstract The first metal, [Ni(dddt)2]3(HSO4)2, among the class of M(dddt)2 cation salts has been obtained. Its structure and conducting properties have been studied. [Ni(dddt)2]3(HSO4)2 has been found to be isostructural to the (ET)3(HSO4)2 salt and their conducting properties are compared. [Ni(dddt)2]3(HSO4)2 retains its metallic state to lower temperatures (∼ 25 K) than (ET)3(HSO4)2 (∼ 130 K).

ET cation-radical salts with metal complex anions

Crystal structures and electrical properties of ET2Cu5I6, ET4[Pt(CN)4], ET4[(Pt(CN)4]C2H3Cl3, and ET3(ZnCl4)2 are described. Bond lengths and angles in ET2+ dication and ET+ cation-radical have been compared for ET3(ZnCl4)2.

New cation-radical salts of BEDT-TTF with the octahedral metal complex anions PtCl62−, PtBr62−, TeCl62− and SnCl62−. Synthesis, structure and properties

Abstract A new series of isostructural cation-radical salts of bis(ethylene)dithiotetrathiafulvalene (BEDT-TTF) with the octahedral metal complex dianions PtCl62−, PtBr62−, TeCl62− and SnCl62− have been obtained. The crystal structure of the (BEDT-TTF)4PtCl6C6H5CN salt has been determined. Although it should be attributed to the k-type of BEDT-TTF metallic salts due to the packing arrangement of the BEDT-TTF molecules, it undergoes a first-order transition into the insulating state at 250 K. Application of a pressure higher than 6 kbar results in a new conducting state. The complexes of (BEDT-TTF) with the anions PtBr62−, TeCl62− and SnCl62− exhibit semiconducting properties.

Endohedral metallofullerenes M@C82 (M=La, Y): synthesis and transport properties

Endohedral metallofullerenes M@C2n (M=La, Y) were synthesized by the arc-discharge method using optimum electric arc parameters. It was also shown that an organic solvent (N,N-dimethylformamide) is successfully used in selective extraction of M@C2n. We identified the resulting products by mass spectrometry, electron spectrophotometry, EPR and X-ray fluorescence spectroscopy. The resulting N,N-dimethylformamide extracts of La@C2n and Y@C2n are shown to be free of empty fullerenes and appear as a mixture of endometallofullerenes M@C2n whose main ingredient is M@C82 (∼80 wt%). Transport properties of the extracts of La@C82 and Y@C82 were studied using pressed pellets. It was found that oxygen and heat treatment affect conductivity of endometallofullerenes. Heat treatment results in a three-order increase of conductivity from 10−5 upto 10−2 Ohm−1 cm−1

Structure and magnetotransport properties of the new quasi-two-dimensional molecular metal {beta} Double-Prime -(BEDT-TTF){sub 4}H{sub 3}O[Fe(C{sub 2}O{sub 4}){sub 3}] {center_dot} C{sub 6}H{sub 4}Cl{sub 2}

The β″-(BEDT-TTF)4AI[MIII(C2O4)3] · G(AI=NH4+, H3O+, K+, Rb+; MIII=Fe, Cr; G = “guest” solvent molecule) family of layered molecular conductors with magnetic metal oxalate anions exhibits a pronounced dependence of the conducting properties on the type of neutral solvent molecules introduced into the complex anion layer. A new organic dichlorobenzene (C6H4Cl2)-containing conductor of this family, namely, β″-(BEDT-TTF)4H3O[Fe(C2O4)3] · C6H4Cl2, is synthesized. The structure of the synthesized single crystals studied by X-ray diffraction is characterized by the following parameters: a = 10.421(1) Å, b= 19.991(2) Å, c= 35.441(3) Å, β = 92.87(1)°, V= 7374(1) Å3, space groupC2/c, and Z = 4. In the temperature range 0.5&2-300 K, the conductivity of the crystals is metallic without changing into a superconducting state. The magnetotransport properties of the crystals are examined in magnetic fields up to 17 T at T = 0.5 K. In fields higher than 10 T, Shubnikov-de Haas oscillations are detected, and the Fourier spectrum of these oscillations contains two frequencies with maximum amplitudes of about 80 and 375 T. The experimental results are compared with the related data obtained for other phases of this family. The possible structural mechanisms of the effect of a guest solvent molecule on the transport properties of the β″-(BEDT-TTF)4AI[MIII(C2O4)3] · G crystals are analyzed.

Crystal structures and electrical properties of ET3Cl2.2H2O and ET4Cl2.4H2O organic metals

Abstract Synthesis, crystal structures and electrical properties of ET-chlorides, ET 3 Cl 2 .2H 2 O and ET 4 Cl 2 .4H 2 O, are described. Both cation-radical salts are organic metals with the metal dielectric transition at ∼ 150 K and ∼ 20 K, respectively.