Redetermination of the Tutton’s salt Cs2[Cu(H2O)6](SO4)2

The crystal structure of dicaesium hexa-aqua-copper(II) bis-[sulfate-(VI)], Cs2[Cu(H2O)6](SO4)2, has been redetermined from single-crystal X-ray diffraction data. In comparison with the previous refinement based on single-crystal neutron data [Shields & Kennard (1972). Cryst. Struct. Commun. 1, 189-191], the results show an improved precision and benefit from inclusion of anisotropic displacement parameters for the non-H atoms. The structure is characterized by a mean Cu - O bond length of 2.094 Å. The [Cu(H2O)6] octa-hedron ( symmetry) is strongly distorted because of the Jahn-Teller effect, with a calculated distortion parameter of 0.0054. The Cs+ cation is ninefold coordinated by seven O atoms and two water mol-ecules, with a mean Cs - O bond length of 3.238 Å. © International Union of Crystallography 2007.