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]

Journal Article · Wed Jan 07 04:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00235a014· OSTI ID:6874500

Whangbo, M; Williams, J M; Schultz, A J; Emge, T J; Beno, M A

On the basis of the crystal structures of ..beta..-(ET)/sub 2/X (X/sup -/ = IBr/sub 2//sup -/, AuI/sub 2//sup -/, I/sub 3//sup -/) determined at low temperature under ambient and applied pressure, they examined the structural factors responsible for the occurrence of the structural modulation in ..beta..-(ET)/sub 2/I/sub 3/ under ambient pressure, its disappearance under pressure greater than approx. 0.5 kbar, and its effect on the superconducting transition temperature T/sub c/ and the dependence of T/sub c/ on anion X/sup -/ in ..beta..-(ET)/sub 2/X. ET is an abbreviation for BEDT-TTF, i.e., bis(ethylenedithio)tetrathiafulvalene. The electron-phonon coupling constants, lambda, calculated for ..beta..-(ET)/sub 2/X on the basis of the McMillan equation suggest that the lattice softness with respect to translational and/or librational modes of vibration increases in the order ..beta..-(ET)/sub 2/I/sub 3/ < ..beta..-(ET)/sub 2/IBr/sub 2/ < ..beta..-(ET)/sub 2/AuI/sub 2/ < ..beta..*-(ET)/sub 2/I/sub 3/, where ..beta..*-(ET)/sub 2/I/sub 3/ refers to the ..beta..-(ET)/sub 2/I/sub 3/ salt under an applied pressure greater than approx. 0.5 kbar with T/sub c/ similarly ordered 8 K. They also discuss the importance of hydrogen...anion interactions in understanding the lower T/sub c/ values (1-1.5 K) of the other class of organic superconductors (TMTSF)/sub 2/X (X/sup -/ = ClO/sub 4//sup -/, PF/sub 6//sup -/) compared to the ..beta..-(ET)/sub 2/X systems and the implications concerning the synthesis of new organic superconductors.

• Research Organization: North Carolina State Univ., Raleigh
• DOE Contract Number: W-31109-ENG-38; FG05-86ER45259
• OSTI ID: 6874500
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:1; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
BROMIDES
BROMINE COMPOUNDS
CHEMICAL BONDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON-PHONON COUPLING
ELEMENTS
EXPERIMENTAL DATA
GOLD COMPOUNDS
GOLD IODIDES
HALIDES
HALOGEN COMPOUNDS
HYDROGEN
INFORMATION
IODIDES
IODINE BROMIDES
IODINE COMPOUNDS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
ULTRALOW TEMPERATURE