Synthesis, crystal structure and charge-distribution validation of a new alluaudite-type phosphate, Na(2.22)Mn(0.87)In(1.68)(PO(4))(3)

Na(2.22)Mn(0.87)In(1.68)(PO(4)3), sodium manganese indium tris­(phosphate) (2.22/0.87/1.68), was obtained in the form of single crystals by a flux method and was structurally characterized by single-crystal X-ray diffraction. The compound belongs to the alluaudite structure type (space group C2/c) with general formula X(2)X(1)M(1)M(2)(2)(PO(4))(3). The X(2) and X(1) sites are partially occupied by sodium [occupancy 0.7676 (17) and 1/2] while the M(1) and M(2) sites are fully occupied within a mixed distribution of sodium/manganese(II) and manganese(II)/indium, respectively. The three-dimensional anionic framework is built up on the basis of M(2)(2)O(10) dimers that share opposite edges with M(1)O(6) octa­hedra, thus forming infinite chains extending parallel to [10[Image: see text]]. The linkage between these chains is ensured by PO(4) tetra­hedra through common vertices. The three-dimensional network thus constructed delimits two types of hexa­gonal channels, resulting from the catenation of M(2)(2)O(10) dimers, M(1)O(6) octa­hedra and PO(4) tetra­hedra through edge- and corner-sharing. The channels are occupied by Na(+) cations with coordination numbers of seven and eight.