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Item Open Access The preparation of new metallic charge-transfer complexes: anthra [9.1-cd:10.5-c'd'] bis [1.2] dithiol (TTA), -diselenol (TSA) and their polyiodides(1982) Endres, Helmut; Keller, Heimo J.; Queckbörner, Jobst G.; Veigel, Jürgen; Schweitzer, DieterThe donors TTA and TSA were prepared starting from 1.5-dichloro-9.10-anthracenedione which was converted into 1.5.9.10-tetrachloroan-thracene (TCA) by two alternating chlorination and elimination steps. TCA was reacted under a dry argon atmosphere with suspensions of Na2S2 and Na2Se2 to yield TTA and TSA, respectively. Action of elemental iodine gives highly conductive polyiodides of both donors. Single crystals of TSA·I1.2 actually behave metallic between 220 and 300 K. The X-ray structure of TSA and TSA·I1.2 allows a comparison of intermolecular distances in the neutral and the partially oxidized, ionic stacks of the donor.Item Open Access TCNQ salts of planar metal complex cations: novel molecular conductors and semiconductors(1985) Endres, Helmut; Bongart, August; Nöthe, Dietrich; Hennig, Ingolf; Schweitzer, Dieter; Helberg, Hans W.; Schäfer, HerbertThe facile variation of positive charge of oxamide oxime metal complexes, caused by acid-base equilibrium, allows the growth of single crystals of their TCNQ salts. 1:1 salts consist of reqular segregated stacks of the components, with metallic room temperature behaviour of the Ni compound, the Pt compound being a semiconductor. Room temperature conductivities are of the order of 10 Siemens per cm. A 2:3 Pt complex TCNQ salt contains segregated acceptor stacks with half a negative charge per molecule. These stacks run perpendicular to mixed stacks -D-D-A-D-D-A-, with integral charges on donors D and acceptors A.Item Open Access Radical cation salts of BEDT-TTF and an unsymmetrical BEDT-TTF derivative(1986) Schweitzer, Dieter; Bender, Klaus; Endres, Helmut; Gärtner, Stephan; Heid, Rolf; Heinen, Ilsabe; Keller, Heimo J.; Weber, Angelika; Weger, MeirInvestigations of several BEDT-TTF and DIMET radical salts are presented. Measurements on β-(BEDT-TTF)2IAuI crystals show that their conducting and superconducting properties might vary strongly depending on the decomposition of (IAuI)− anions during the electrochemical process.Item Open Access Electrocrystallization and structures of perylene radical salts: hexaperylene perchlorate, (C20H12)6+ClO4-, triperylene perchlorate, (C20H12)3+ClO4-, and diperylene hexafluorophosphate-tetrahydrofuran (3/2), (C20H12)2+PF6-.2/3C4H8O(1985) Endres, Helmut; Keller, Heimo J.; Müller, Barbara; Schweitzer, DieterCrystals grown by electrocrystallization, species obtained depending on perylene concentration. Room-temperature data collect ions, Mo Kat λ = 0·71069 A. 6:1 salt: Mr= 1613·3, triclinic. pl, a = 12·57 1 (7), b = 13·699(5). c = 13.835(II)A, α = 110·43 (4), β= 107·13 (7), γ= 107·09 (4)°, V = 1913A3, Z = 1, Dx = 1.40gcm-3, μ= 1.1 cm- ', F(OOO) = 841, final R = 0·077 for 3171 observed reflections. The structure contains three independent perylene π dimers arranged nearly perpendicularly to each other. The anions are severely disordered or freely rotating. 3:1 salt: Mr = 856·4, triclinic, PI, a = 13·009(8), b= 13.821 (10), c= 13·850(15)A, α = 66·05(7), β = 83·36 (8). γ= 63·5 1 (6)°, V = 2030A3, Z = 2, Dx= 1.40gcm-3 , μ= 1·5cm-1 , F(OOO) = 890, final R = 0· 138 for 3523 observed reflections. Tetrameric perylene stacks are surrounded on four sides by single perylene species, having their planes nearly perpendicular to the molecular planes in the stacks. 2:1 salt: Mr = 697· 7, monoclinic, P2/m, a = 13·04(1), b = 14 · 12 (1), c = 13·75 (1)A, β=110·80 (2)°, V = 2367 A3, Z = 3, Dx = 1·47 g cm-3',μ= 1·5 cm- ', F(OOO) = 1079, final R =0· 121 for 1737 observed reflections. Nearly regular perylene stacks are surrounded by single perylene species in a way similar to the 3:1 salt. The thf solvent and one of the perylene molecules are disordered over two orientations.Item Open Access Synthesis, structure and physical properties of a two-dimensional organic metal, di[bis(ethylenedithiolo)tetrathiofulvalene] triiodide, (BEDT-TTF)2+I3-(1984) Bender, Klaus; Hennig, Ingolf; Schweitzer, Dieter; Dietz, Klaus; Endres, Helmut; Keller, Heimo J.Electrical oxidation of bis(ethylenedithiolo)tetrathiofulvalene (BEDT-TTF) 1 in a nitrogen saturated tetrahydrofurane solution containing (n-C4H10)4N+I3 as electrolyte results in the deposition of crystal plates of (BEDT-TTF)+2I3 (C10H8S8)2I3. These two dimensional crystals are triclinic, space group P1, a = 9.211(2), b=10.850(4), c = 17.488(5) Aring, agr=96.95(2), β = 97.97(2), γ = 90.75(2)°, V = 1717 Aring3, Mr = 1150.01, Z=2, Dx =2.22 g cm-3. Rw = 0.037 for 2462 observed reflections. Sheets of alternating cations and anions occur in the compound. The most prominent intermolecular S-S contacts (∼3.5Aring) are found between the stacks of BEDT-TTF. The stacking of the molecules and the interstack contacts give the compound a two-dimensional character which influences the physical properties.Item Open Access α- and β-(BEDT-TTF)2+I3-: two dimensional organic metals(1985) Hennig, Ingolf; Bender, Klaus; Schweitzer, Dieter; Dietz, Klaus; Endres, Helmut; Keller, Heimo J.; Gleitz, Arno; Helberg, Hans W.Electronic properties of α- and β-(BEDT-TTF)2I3 crystals are reported.Item Open Access Organic metals from simple aromatic hydrocarbons: perylene radical salts(1985) Schweitzer, Dieter; Hennig, Ingolf; Bender, Klaus; Endres, Helmut; Keller, Heimo J.Crystal structures, temperature dependent thermopower and conductivity measurements of several metallic perylene radical salt phases are discussed.Item Open Access Radical cation salts of an unsymmetrical BEDT-TTF derivative: DIMET(1987) Bender, Klaus; Endres, Helmut; Gärtner, Stephan; Gogu, Emil; Heid, Rolf; Heinen, Ilsabe; Keller, Heimo J.; Kraatz, Andrea; Schweitzer, DieterA surprising fact in the structures of the organic superconductors (TMTSF)2 Cl04 and -β-(BEDT-TTF)2X (X=I3-, IBr2- and AuI2-) is that there exists a slight dimerisation of the donor molecules within the stacks of these radical cation salts. Therefore, the question arises whether a more pronounced dimerisation in organic radical salts of this type leads to stronger intra- and interstack interactions and to stronger couplings between the unpaired electrons. This might result in an increase of the transition temperature to superconductivity. A step in this direction is the preparation of "unsymmetrical" donors like DIMET, which was synthesized recently. This new donor was electrocrystallized by us in different solvents using tetrabutylammonium salts of various anions like ClO4-, ReO4-, NO3-, I3-, (AuI2)-, PF6-, ASF6- and SbF6- as electrolytes. With all these anions radical salts were obtained and in some cases even several crystallographic different phases.Item Open Access (BEDT-TTF)2+J3- : a two-dimensional organic metal(1984) Bender, Klaus; Dietz, Klaus; Endres, Helmut; Helberg, Hans W.; Hennig, Ingolf; Keller, Heimo J.; Schäfer, Herbert; Schweitzer, DieterTemperature-dependent thermopower-, dc- and microwave-conductivity measurements on the two-dimensional organic metal (BEDT-TTF)2+J3- are reported.Item Open Access Preparation, structure and investigations of BEDT-TTF trihalides(1985) Endres, Helmut; Hiller, M.; Keller, Heimo J.; Bender, Klaus; Gogu, Emil; Heinen, Ilsabe; Schweitzer, DieterCrystals of the β-phases of (BEDT-TTF)2Br-I-Br (1) and (BEDT-TTF)2I-I-Br (2) have been isolated by electrocrystallization. The solids can be obtained using different tetrabutylammonium trihalides containing iodine and bromine as supponing electrolytes. Cyclovoltammetric results show clearly that the trihalide anions are involved in the oxidation reactions near the anode which finally lead to the crystals.