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 P21/c. The asymmetric unit contains one Mg (site symmetry 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.