Redetermination of the hexa­gonal struvite analogue Cs[Mg(OH(2))(6)](PO(4))

The structure of the hexa­gonal modification of caesium hexa­aqua­magnesium phosphate has been redetermined from single-crystal X-ray data. The previous refinement from photographic data [Ferrari, Calvaca & Nardelli (1955 ▶). Gazz. Chim. Ital. 85, 1232–1238] was basically confirmed, but with all H atoms located and with all non H-atoms refined with anisotropic displacement parameters. The structure can be derived from the NiAs structure type: the PO(4) tetra­hedra (3m. symmetry) are on the Ni positions and the complex [Mg(OH(2))(6)] octa­hedra (3m. symmetry) are on the As positions. The building units are connected to each other by hydrogen bonds. The Cs(+) cations (3m. symmetry) are located in the voids of this arrangement and exhibit a distorted cubocta­hedral 12-coordination by the O atoms of the water mol­ecules.