(BaMn2MnIII)-Mn-II(PO4)(3)

The title compound, barium trimanganese tris(orthophosphate), was synthesized hydrothermally. Its structure is isotypic with the lead and strontium analogues AMn(2)(II)Mn(III) (PO4)(3) (A = Pb, Sr). Except for two O atoms on general positions, all atoms are located on special positions. The Ba and one P atom exhibit mm2 symmetry, the Mn-II atom 2/m symmetry, the Mn-III atom and the other P atom .2. symmetry and two O atoms are located on mirror planes. The crystal structure contains two types of chains running parallel to [010]. One chain is linear and is composed of alternating (MnO6)-O-III octahedra and PO4 tetrahedra sharing vertices; the other chain has a zigzag arrangement and is built up from two edge-sharing (MnO6)-O-II octahedra connected to PO4 tetrahedra by edges and vertices. The two types of chains are linked through PO4 tetrahedra into an open three-dimensional framework which contains channels parallel to [100] and [010] in which the Ba-II ions are located. The alkaline earth cation is surrounded by eight O atoms in the form of a slightly distorted bicapped trigonal prism.