Neutron diffraction evidence for unusual cohesive H-bonding interactions in. beta. -(BEDT-TTF)/sub 2/X organic superconductors. [. beta. -bis(ethylenedithio)tetrathia fulvalene X; X = AuI/sub 2/ or I/sub 3/]
In order to determine the nature and exact geometries of the interionic interactions that are responsible for crystal cohesion between the sheetlike networks of radical cation molecules and the halide-containing anions in the layered organic conductors of the type ..beta..-(ET)/sub 2/X, the authors have undertaken low-temperature (20 K) neutron diffraction studies of the X/sup -/ = AuI/sub 2//sup -/ and I/sub 3//sup -/ salts. For these synthetic organic superconductors, ..beta..-(ET)/sub 2/AuI/sub 2/ has the highest T/sub c/ (approx. 5K) at ambient pressure, and ..beta..-(ET)/sub 2/I/sub 3/ has the highest T/sub c/ (approx. 8 K) under a nonhydrostatic pressure of 1.3 kbar. The discovery of very short H...I contacts in ..beta..-(ET)/sub 2/AuI/sub 2/ is surprising because such interactions are generally assumed to be weak. There are important implications for the design and synthesis of new ..beta..-(ET)/sub 2/X systems where the X/sub n//sup -/ anions contain halide (I, Br, Cl, F) atoms, namely, that H-bonding interactions of the type H...X play a major role in determining the crystal cohesive forces between donors and anions thereby controlling compound formation.
- Research Organization:
- Argonne National Lab., IL
- DOE Contract Number:
- W-31-109-ENG-38; AC02-76CH00016
- OSTI ID:
- 5534174
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 108:13
- Country of Publication:
- United States
- Language:
- English
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Effect of structural disorder on organic superconductors: a neutron diffraction study of high-T/sub c/. beta. -(BEDT-TTF)/sub 2/I/sub 3/ at 4. 5 K and 1. 5 kbar. [Bis(ethylenedithio)tetrathia-fulvalene iodide]
Importance of intermolecular hydrogen. hydrogen and hydrogen. anion contacts for the lattice softness, the electron-phonon coupling, and the superconducting transition temperatures, T/sub c/, of organic conducting salts. beta. -(ET)/sub 2/X (X/sup -/ = IBr/sub 2//sup -/, AuI/sub 2//sup -/, I/sub 3//sup -/). [ET = bis(ethylenedithio)tetrathiafulvalene]
Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GOLD IODIDES
INTERMOLECULAR FORCES
SUPERCONDUCTIVITY
IODIDES
TTF
EXPERIMENTAL DATA
NEUTRON DIFFRACTION
SUPERCONDUCTORS
COHERENT SCATTERING
DATA
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
GOLD COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IODINE COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
TRANSITION ELEMENT COMPOUNDS
360603* - Materials- Properties
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)