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

The crystal structure of dicaesium hexaaquacopper(II) bis[sulfate(VI)], Cs-2[ 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 A. The [Cu(H2O)(6)] octahedron (1 symmetry) is strongly distorted because of the Jahn-Teller effect, with a calculated distortion parameter Delta of 0.0054. The Cs+ cation is ninefold coordinated by seven O atoms and two water molecules, with a mean Cs - O bond length of 3.238 angstrom.