A two-dimensional radical salt based upon BEDT-TTF and the dimeric, magnetic anion [Fe(tdas)2]22−: (BEDT-TTF)2[Fe(tdas)2] (tdas = 1,2,5-thiadiazole-3,4-dithiolate)

Abstract

In an attempt to synthesize new synthetic metals which couple magnetic properties to conductivity, we prepared the novel salt (BEDT-TTF)₂[Fe(tdas)₂] [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene, hereafter referred to as ET; tdas = 1,2,5-thiadiazole-3,4-dithiolate] by the electrocrystallization technique. The crystal structure of this compound, as determined by single crystal X-ray diffraction, contains conducting, organic ET layers separated by dimerized, magnetic [Fe(tdas)₂]₂²⁻ anions. Due to the magnetic insulating ground electronic state of the ET layer, thermally activated conductivity is observed, with a room temperature value of about 1 S cm⁻¹. This salt was also characterized by EPR spectroscopy, dc magnetization measurements and Raman spectroscopy. The electronic structure of the ET layers was investigated by extended Hückel tight-binding calculations, and the spin exchange interactions of the ET and [Fe(tdas)₂]⁻ layers were examined by spin-dimer analysis.