Acta Cryst. (2005). E61, i275-i277  [ doi:10.1107/S1600536805036731 ]

Potassium magnesium hydrogendiphosphate dihydrate

B. El Bali, A. Alaoui Tahiri, M. Lachkar, M. I. Arriortua and M. K. Urtiaga

Abstract: The title compound, KMg(HP₂O₇)·2H₂O, is isotypic with other members of the series KM(HP₂O₇)·2H₂O, where M = Mn, Co and Zn. The structure consists of a three-dimensional framework of [MgHP₂O₇]^- layers parallel to (100) linked by K⁺ cations and hydrogen-bonding interactions. The metal ions and water O atoms lie on mirror planes, as does the bridging O atom of the eclipsed (HP₂O₇)^3- anion. The acid H atom of the diphosphate anion is split into two half-occupied positions around a center of inversion.

Online 19 November 2005

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