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 orthorhombic 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 tetrahedra. Each BaO₁₂ polyhedron shares corners with eight ClO₄ tetrahedra, and edges with two ClO₄ tetrahedra. Each ClO₄ tetrahedron shares corners with four BaO₁₂ polyhedra, and an edge with the other BaO₁₂ polyhedron.