Composé à charpente bidimensionnelle K₃Fe₃(AsO₄)₄

Tripotassium triiron(III) tetraarsenate, K₃Fe₃(AsO₄)₄, has been synthesized at high temperature by solid-state reaction. The structure is built up from corner- and edge-sharing between FeO₆ octahedra and AsO₄ tetrahedra. The structure can be described as infinite anionic layers parallel to the (010) plane. Alkali metal cations are located in the interlayer space. The relationship between the title compound and K₃Fe₃(PO₄)₄·H₂O structures is discussed. The title compound is isostructural with K₃Cr₃(AsO₄)₄.

Un nouveau diarséniate Cs₃Fe₂(AsO₄)₃ à environnement exclusivement pentagonal du fer

The crystal structure of the new iron(III) arsenate, viz. tricaesium diiron(III) tris(arsenate), Cs₃Fe₂(AsO₄)₃, is built up from corner-sharing AsO₄ tetrahedra and FeO₅ trigonal bipyramids forming a three-dimensional open framework, which contains two channels running along the c axis where the Cs⁺ cations are located. This compound is a rare example of an oxide possessing Fe exclusively in trigonal-bipyramidal coordination.