Distrontium trimanganese(II) bis-(hydro-gen-phosphate) bis-(ortho-phosphate)

The title compound, Sr2Mn3(HPO4)2(PO4)2, was synthesized under hydro-thermal 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 octa-hedra (one almost undistorted, one considerably distorted), one PO3OH and one PO4 tetra-hedron. The centrosymmetric MnO6 octa-hedron is linked to two other MnO6 octa-hedra by edge-sharing, forming infinite zigzag chains parallel to [010]. The PO3OH and PO4 tetra-hedra connect these chains through common vertices or edges, resulting in the formation of sheets parallel to (100). The Sr(2+) cation is located in the inter-layer 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 inter-layer 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.