Acta Cryst. (2004). E60, i139-i141  [ doi:10.1107/S1600536804026182 ]

Fe^II₃Fe^III₄(AsO₄)₆, the first arsenate adopting the Fe₇(PO₄)₆ structure type

M. Weil

Abstract: Single crystals of triiron(II) tetrairon(III) hexakis[orthoarsenate(V)], Fe₇(AsO₄)₆, were grown by chemical transport reactions. The structure is isotypic with other M^II₃M^III₄(XO₄)₆ compounds (M = first row transition metals; X = P, V) which adopt the Fe₇(PO₄)₆ structure type. The structure includes four independent cation sites, two of which are occupied by divalent and two by trivalent iron cations. Slightly distorted [FeO₆] octahedra and [FeO₅] trigonal bipyramids share edges and form infinite chains, which are linked by corner-sharing with AsO₄ tetrahedra and with [FeO₆] octahedra into a three-dimensional network. Except for one Fe site with symmetry occupied by a divalent iron cation, all other atoms are located in general positions.

Online 22 October 2004

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