Magnesium perchlorate anhydrate, Mg(ClO4)2, from laboratory X-ray powder data

The previously unknown crystal structure of magnesium perchlorate anhydrate, determined and refined from laboratory X-ray powder diffraction data, represents a new structure type. The title compound was obtained by heating magnesium perchlorate hexahydrate at 523 K for 2 h under vacuum and it crystallizes in the monoclinic space group P2(1)/c. The asymmetric unit contains one Mg (site symmetry (1) over bar on special position 2a), one Cl and four O sites (on general positions 4e). The structure consists of a three-dimensional network resulting from the corner-sharing of MgO6 octahedra and ClO4 tetrahedra. Each MgO6 octahedron share corners with six ClO4 tetrahedra. Each ClO4 tetrahedron shares corners with three MgO6 octahedra, with one O-atom corner dangling. The ClO4 tetrahedra are oriented in such a way that one-dimensional channels parallel to [100] are formed between the dangling O atoms.