The new semiconducting magnetic charge transfer salt (BEDT-TTF) 4·H 2O·Fe(C 2O 4) 3·C 6H 5NO 2: crystal structure and physical properties

Abstract

The structure, resistivity and ESR of a new molecular charge transfer salt β-(BEDT-TTF) 4·H 2O·Fe(C 2O 4) 3·C 6H 5NO 2 (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 H 2O and Fe(C 2O 4) 3 3−, with C 6H 5NO 2 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) A ̊ , β = 92.21(9)°; V = 7342.0(5) A ̊ 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 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(C 2O 4) 3·C 6H 5NO 2, where A = H 2O, K +, NH 4 +, is also carried out.