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)·H2O, the thiacalix[4]arenetetrasulfonate (= TCAS4−) anions adopt a cone-type conformation with an additional water molecule as a guest molecule in the hydrophobic cavity. The TCAS4− 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⋯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.

In the crystal structure of the title compound, [Co(H 2 O) 6 ] 2 -(C 24 H 12 O 16 S 8 )ÁH 2 O, the thiacalix[4]arenetetrasulfonate (= TCAS 4À ) anions adopt a cone-type conformation with an additional water molecule as a guest molecule in the hydrophobic cavity. The TCAS 4À 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-HÁ Á ÁO hydrogenbond interactions exist between the aqua ligands of the [Co(H 2 O) 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.

Bis
In the crystal structure of (I) the TCAS 4molecules adopt the cone-type conformation. The Co 2+ ions are not directly bonded to the TCAS 4moieties, but exist as two octahedral aqua complexes, [Co(H 2 O) 6 ] 2+ , both with m symmetry ( Figure   1, Table 1

S2. Experimental
A solution of Na 4 (S 8 C 24 O 16 H 12 ) . 14H 2 O (=Na 4 TCAS . 14H 2 O) in 2 M HCl and a 2M HCl solution containing CoCl 2 . 6H 2 O were mixed in the molar ratio (Co/Na 4 TCAS = 5), poured into a vial and stirred for 1 h. This solution was then kept at room temperature from which pale pink crystals of (I) were obtained within a few days. Elemental analysis of (I) is in agreement with the refined structure model. Found: C 24.85, H 2.89%; calculated for (I): C 24.74, H 3.29%.

S3. Refinement
Refinement was performed using 4296 reflections (5 < 2θ < 51°) out of 4319 independent reflections. The positions of all the H atoms were initially located from a difference map. All H atoms were refined by using the riding model approximation with C-H distances in the range 0.77-0.93Å. The isotropic displacement parameters for all H atoms were fixed at 1.2 times the value of the equivalent isotropic displacement parameter of their carrier atom. The H atoms attached to the water molecule in the hydrophobic cavity of thiacalix[4]arenetetrasulfonate could not be found from a difference map. Therefore the positions of the H atoms were not refined. The maximum of the remaining electron density is located 2.66Å away from atom O15.  The molecular entities of (I) with the atom-labelling scheme and displacement ellipsoids drawn at 50% probability level.
Labelling of H atoms has been omitted for clarity. [Symmetry code:

Figure 2
The projection of the structure of (I) along the b axis. Special details Refinement. Refinement was performed using 4296 reflections (5 < 2θ < 51°). The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R factor (gt) are based on F. The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R factor (gt).