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 beta-(BEDT-TTF)(4) . H2O . Fe(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 beta-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) Angstrom, beta = 92.21(9)degrees; V = 7342.0(5) Angstrom(3), space group C2/c; Z = 4. The conductivity of this salt at room temperature is 10 S cm(-1) and it shows semiconducting behaviour from 20 to 300 K. The ESR linewidth is found to be 38.1 (300 K), which is substantially wider than a typical linewidth for BEDT-TTF based radical cation salts of the beta-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+, NH4+, is also carried out. (C) 1998 Elsevier Science S.A. All rights reserved.