The title compound is a double-layered hydroxide which belongs to the solid solution Ca2Al(OH)6BrxCl1−x·2H2O, where x can vary from 0 to 1. Chloride and bromide anions of the negatively charged interlayer [Br0.5Cl0.5·2H2O]− share statistically the same crystallographic site. Al3+ and Ca2+ cations are coordinated by six and seven O atoms, respectively. All water molecules are bonded to Ca2+ cations and assume the seventh coordination position.
Cs3CoCl5 has been determined at 10 K with high precision. The Co atom is at a site with symmetry, one Cs atom is at a site with 42 symmetry, the other has mm site symmetry, one Cl ligand has 4/m symmetry and the other has m symmetry.