Stable Metallic Behavior and Antiferromagnetic Ordering of Fe(III) d Spins in (EDO-TTFVO)2·FeCl4
摘要:
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 beta' '-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 pi-d interaction. This salt showed a stable metallic conducting behavior down to 0.3 K and an antiferromagnetic ordering at TN approximately 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 pi-d interactions between the donor molecules and the FeCl4- ions because the field dependence of magnetoresistances was remarkably affected below the antiferromagnetic transition temperature.
Fe<sub>2</sub>OCl<sub>6</sub><sup>2−</sup> Salt Formed by Electrochemical Oxidation of Ethylenedioxytetrathiafulvalenoquinone-1,3-dithiolemethide in the Presence of FeCl<sub>4</sub><sup>−</sup> Ion with a Silicon Wafer Electrode
作者:Tadahiro Koike、Sayo Yokota、Hideki Fujiwara、Toyonari Sugimoto、Satoru Noguchi、Dominique de Caro、Lydie Valade
DOI:10.1021/ic8006487
日期:2008.8.1
Electrochemical oxidation of a bent donor molecule, ethylenedioxytetrathiafulvalenoquinone-1,3-dithiolmethide (2), in chlorobenzene (PhCl)/ethanol containing NBu4FeCl4 as a supporting electrolyte is performed using an undoped silicon wafer electrode. Black crystals of 2(6) center dot Fe2OCl6 center dot 2PhCl are obtained that have a different molecular formula from that of 2(2) center dot FeCl4 crystals obtained previously using a platinum rod electrode. The new crystal has a structure composed of alternately stacked layers of 2 molecules and Fe2OCl62- ions, whose Fe-O-Fe bond is completely linear and for which the geometry around the Fe atom is almost tetrahedral. The electrical resistivity decreases with temperature until ca. 200 K, but below this temperature, it gently increases. The magnetic susceptibility (chi(p)) observed can be described by the sum of chi(p) obeying a Curie-Weiss law for the impurity spins and of chi(p) obeying a dimer model with a spin-exchange integral (J similar to -180 K) in each Fe2OCl62- ion, which is also weakly coupled to neighboring Fe2OCl62- ions through an additional exchange interaction.
Stable Metallic Behavior and Antiferromagnetic Ordering of Fe(III) <i>d</i> Spins in (EDO-TTFVO)<sub>2</sub>·FeCl<sub>4</sub>
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 beta' '-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 pi-d interaction. This salt showed a stable metallic conducting behavior down to 0.3 K and an antiferromagnetic ordering at TN approximately 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 pi-d interactions between the donor molecules and the FeCl4- ions because the field dependence of magnetoresistances was remarkably affected below the antiferromagnetic transition temperature.