Calcium chloride rhenate(VII) dihydrate

In the nearly tetra­hedral rhenate(VII) anion of calcium chloride rhenate(VII) dihydrate, all constituent atoms lie on special positions of m2m (Re) and m (O) site symmetries. The Cl⁻ anion and water O atom lie on special positions of m2m and 2 site symmetry, respectively. The Ca²⁺ ion, also on a special position (m2m), is eight-coordinated in a distorted square-anti­prismatic coordination mode. The crystal has a layered structure stabilized by Ca—O coordination bonds as well as O—H...Cl hydrogen bonds.