Distrontium trimanganese(II) bis­(hydro­gen­phosphate) bis­(ortho­phosphate)

The title compound, Sr₂Mn₃(HPO₄)₂(PO₄)₂, was synthesized under hydro­thermal conditions. In the structure, one of two Mn atoms is located on an inversion centre, whereas all others atoms are located in general positions. The framework structure is built up from two types of MnO₆ octa­hedra (one almost undistorted, one considerably distorted), one PO₃OH and one PO₄ tetra­hedron. The centrosymmetric MnO₆ octa­hedron is linked to two other MnO₆ octa­hedra by edge-sharing, forming infinite zigzag chains parallel to [010]. The PO₃OH and PO₄ tetra­hedra connect these chains through common vertices or edges, resulting in the formation of sheets parallel to (100). The Sr²⁺ cation is located in the inter­layer space and is bonded to nine O atoms in form of a distorted polyhedron and enhances the cohesion of the layers. Additional stabilization is achieved by a strong inter­layer O—H...O hydrogen bond between the PO₃OH and PO₄ units. The structure of the title phosphate is isotypic to that of Pb₂Mn₃(HPO₄)₂(PO₄)₂.