The New Semiconducting Magnetic Charge Transfer Salt (BEDT-TTF)₄ • H₂O • Fe(C₂O₄)₃ • C₆H₅NO₂: Crystal Structure and Physical Properties

The structure, resistivity and ESR of a new molecular charge transfer salt β-(salt (BEDT-TTF)₄ • H₂Fe(C₂O₄)₃ • C₆H₅NO₂ (BEDT-TTF = bis (ethylenedithio)tetrathiofulvalene) are studied. The structure of the salt consists of successive layers of BEDT-TTF which are packed according to β-type and layers of approximately hexagonal geometry containing alternating H₂O and Fe(C₂O₄)₃^3-, with C₆H₅NO₂ lying within the hexagonal cavity. Its main crystallographic parameters are found to be: M = 1999.6(1), a = 10.31(8), b = 20.14(8), c = 35.34(4) Å, β = 92.21(9)°; V = 7342.0(5) ų, space group C₂/c; Z = 4. The conductivity of this salt at room temperature is 10 S cm^-1 and shows semiconducting behaviour from 20 to 300 K. The ESR line width is found to be 38.1 (300 K), which is substantially wider than a typical line width for BEDT-TTF based radical cation salts of the β-type, indicating a two-dimensional character. The comparison of crystal structure and properties of the title compound with other salts of this family (BEDT-TTF)₄ • A • Fe(C₂O₄)₃ • C₆H₅NO₂, where A = H₂O, K⁺ or NH₄⁺, is also carried out. © 1998 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.