Crystal structure of barium perchlorate anhydrate, Ba(ClO4)2, from laboratory X-ray powder data

The previously unknown crystal structure of barium perchlorate anhydrate, determined and refined from laboratory X-ray powder diffraction data, represents a new structure type. The title compound was obtained by heating hydrated barium perchlorate [Ba(ClO4)2·xH2O] at 423 K in vacuo for 6 h. It crystallizes in the ortho-rhom-bic space group Fddd. The asymmetric unit contains one Ba (site symmetry 222 on special position 8a), one Cl (site symmetry 2 on special position 16f) and two O sites (on general positions 32h). The structure can be described as a three-dimensional polyhedral network resulting from the corner- and edge-sharing of BaO12 polyhedra and ClO4 tetra-hedra. Each BaO12 polyhedron shares corners with eight ClO4 tetra-hedra, and edges with two ClO4 tetra-hedra. Each ClO4 tetra-hedron shares corners with four BaO12 polyhedra, and an edge with the other BaO12 polyhedron.