Browsing by Author "Bongart, August"

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    A novel molecular metal: (oxamide oximato)(oxamide oxime)nickel(II) tetracyanoquinodimethanide, [Ni(oaoH)(oaoH2)]tcnq, and physical properties of its semiconducting Pt analogue
    (1985) Endres, Helmut; Bongart, August; Nöthe, Dietrich; Hennig, Ingolf; Schweitzer, Dieter; Schäfer, Herbert; Helberg, Hans W.; Flandrois, Serge
    (C4H11N8NiO4)+(C12H4N4)-, Mr = 498.09 is triclinic, p1, a -=3.7718(6), b = 7.436(2), c =17.511(4) A, a=88.67(2), β=86.93(2), γ=85.05(2), γ= 488.51 A 3, Z = 1, d c=1.69 gcm -3, final R w= 0.035 for 1454 observed independent reflections. The crystals consist of segregated regular parallel stacks of planar metal complex cations and tcnq - counterions with intermolecular H bonds stabilizing the structure. The compound is metallic at room temperature. A metal to semiconductor transition around 230 K shows up in thermopower data, in the microwave conductivity and epr around 170 K. It is not visible in the static magnetic susceptibility.
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    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, Herbert
    The 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.