[Open access]

Acta Cryst. (2013). E69, i27-i28
[ doi:10.1107/S1600536813008726 ]


N. Bourguiba Fakhar, M. F. Zid and A. Driss

Abstract: The title compound, heptasodium tetrachromium(III) tetrakis(diphosphate) orthophosphate, was synthesized by solid-state reaction. Its structure is isotypic with that of Na7M4(P2O7)4PO4 (M = In, Al) compounds and is made up from a three-dimensional [(CrP2O7)4PO4]7- framework with channels running along [001]. The three Na+ cations are located in the voids of the framework. One of the cations is situated on a general position, one is equally disordered around a twofold rotation axis and one is on a fourfold rotoinversion axis. The isolated PO4 tetrahedron of the anionic framework is also situated on the -4 axis. Structural relationships between the title compound and different diphosphates containing MP2O11 units (M = Mo, V) are discussed.

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