Bis[hexaaquacobalt(II)] 25,26,27,28-tetrahydroxy-2,8,14,19-tetrathiacalix[4]-arene-5,11,17,23-tetrasulfonate monohydrate

In the crystal structure of the title compound, [Co(H2O)(6)](2)(C24H12O16S8) center dot H2O, the thiacalix[4]arenetetrasulfonate (= TCAS(4-)) anions adopt a cone-type conformation with an additional water molecule as a guest molecule in the hydrophobic cavity. The TCAS(4-) anions are arranged in layers in an up-down fashion. These anionic layers alternate with cationic layers consisting of rather regular octahedral cations (symmetry m). Several medium O-H center dot center dot center dot O hydrogen-bond interactions exist between the aqua ligands of the [Co(H2O)(6)] (2+) cations and the O atoms of the sulfonate groups. In addition to the two crystallographically different Co atoms, two S and four O atoms are situated on mirror planes.