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Synthesis, Crystal Structure, and Characterization of the Charge-Transfer Salt (BEDT-TTF)[Fe(C2O4)Cl2](CH2Cl2), {BEDT-TTF = Bis(ethylenedithio)tetrathiafulvalene}



The synthesis, crystal structure, Raman spectra, conductivity, and magnetism of the title charge-transfer salt (1) composed of BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene], one-dimensional [Fe(C2O4)Cl2]n, and the solvent CH2Cl2, are described and interpreted. Electrochemical oxidation of neutral BEDT-TTF in the presence of [(C2H5)3NH][Fe(C2O4)Cl2] in a CH2Cl2/CH3OH solution yields crystals of 1, which crystallizes in triclinic form. In 1, two donor molecules stack in a face-to-face manner as a BEDT-TTF dimer. The BEDT-TTF dimers form a (4,4) grid in the ab plane. The cavity of the (4,4) grid is occupied by two CH2Cl2 molecules. The donor layers are separated by sheets of [Fe(C2O4)Cl2]n anions with a zigzag chain along the a axis. There are S···S interactions between the donors, and S···Cl interactions between the donor and the anion. On the χ vs. T plot, a broad maximum is observed around 45 K, showing the existence of antiferromagnetic interactions between the metal atoms in the low-dimensional system. The formal charge of the donor molecules is assigned 1.0+ based on the bond lengths of the TTF core and on the Raman spectra. The material is a semiconductor with σrt = 1.8 × 10–5 S/cm.