Stable metallic behavior and antiferromagnetic ordering of Fe(III) d spins in (EDO-TTFVO)2•FeCl4

We report the crystal structure and physical properties of the 2:1 FeCl4- salt of a new donor molecule, EDO-TTFVO. Crystal structure analysis of this salt revealed that the donor molecules formed a β″-type two-dimensional conducting layer, and there is a short S⋯Cl contact between the donor molecules and the FeCl4- ions, which is expected to mediate a strong π-d interaction. This salt showed a stable metallic conducting behavior down to 0.3 K and an antiferromagnetic ordering at TN ≈ 3.0 K, indicating that this salt becomes a new antiferromagnetic molecular metal at ambient pressure. The appearance of the magnetic ordering is considered to originate from the strong π-d interactions between the donor molecules and the FeCl4- ions because the field dependence of magnetoresistances was remarkably affected below the antiferromagnetic transition temperature. Copyright © 2005 American Chemical Society.