Abstract: | Na5FeS4 — the First Thioferrate(III) with Discrete Tetrahedral Anions Ruby red crystals of Na5FeS4 were obtained by reacting a stoichiometric mixture of Na2S, Fe, and S at 970 K. The compound is orthorhombic, space group Pbca, with a = 11.947(5), b = 7.091(3), c = 21.54(1) Å, Z = 8. The crystal structure was determined from single crystal diffractometer data. The atomic arrangement – which corresponds to that of Na5GaO4 [1] – is characterized by discrete tetrahedral [FeS4] groups, separated from each other by Na+ cations. Measurements of the magnetic susceptibilities show coupling effects between Fe3+ ions below 28 K. At higher temperatures a Curie-Weiss behaviour indicates a high-spin-state of the Fe3+ ions. Relationships between the interatomic distances and the magnetic moments in alkali thioferrates are discussed. |