Crystal structure of (acetato-κO)(ethanol-κO)[(9S,17S,21S,29S)-9,17,21,29-tetrahydroxy-18,30-dioxaoctacyclo[18.10.0.02,7.08,19.09,17.011,16.021,29.023,28]triaconta-1,3,5,7,11(16),12,14,19,23(28),24,26-undecaene-10,22-dione-κ3 O 18,O 21,O 22]caesium ethanol monosolvate

The title compound, C28H16O8·Cs+CH3O−·2CH3CH2OH, was formed in the supramolecular reaction between a vasarene analogue and caesium fluoride, where the F− ion has been replaced by acetate.


Chemical context
The supramolecular reactions of ligands from the vasarene family with ion-pairs of type M + F À , provided M is a large monovalent cation, have been studied extensively by our group in the past years (Almog et al., 2009(Almog et al., , 2012Bengiat et al., 2016a,b,c). The prerequisite regarding the size of the cation rests in the key role of the fluoride ion in initiating the complex formation (Bengiat et al., 2016b), though the contribution of the F À ion to the stability of the complex once formed has yet to be explored. In several cases, however, the F À ions have been absent from the final complex which contained acetate ions instead. This observation can be explained by the presence of acetic acid (AcOH) residues from the synthesis of the ligand, but the exact mechanism is still unknown. Here, we review the structure of the title complex and the effect of the AcO À anion on its supramolecular features.

Structural commentary
The complex was formed in the reaction of the bis ninhydrin naphthalene-1,3-diol ligand [1] ( Fig. 1) with CsF. As mentioned earlier, we suggest that the presence of residual AcOH results in a selective precipitation with AcO À rather ISSN 2056-9890 than F À in the final complex. Similar to the original vasarene complexes with CsF (Almog et al., 2012;Bengiat et al., 2016b,c), the Cs + ion is stabilized by several interactions with the oxygen-containing functional groups of the ligand: hydroxyl (O3), carbonyl (O4) and etheric (O5), as well as by the additional EtOH solvate molecule (O1E) and the acetate counter-ion (O1A) (Scheme, Fig. 2). Fig. 2 shows the hydrogen bonding between the different unit cells (Table 1) involving a second solvent molecule of EtOH, O2EÁ Á ÁH-O1E and O2E-HÁ Á ÁO2A. Further stabilization of the lattice is achieved by the parallel-displacedstacking between the aromatic rings of the 'side-walls' of ligands in different unit cells with an inter-planar distance of 3.669 (1) Å (Janiak, 2000) (Fig. 3). In other complexes of the vasarane analogues with CsF, there has been an alternating arrangement of ligand and salt layers, forming 'salt channels' that are held by supramolecular interactions of hydrogen bonds, cation-and metal coordination with the ligands (Bengiat et al., 2016b,c). In this case, however, it is suggested that the difference in the ionic radius between the F À (1.33 Å ) and AcO À (1.60 Å ) (Shannon, 1976;Manku, 1980) results in steric hindrance that prevents the tight packing of the lattice (Figs. 4 and 5).

Database survey
The bowl-shaped compound formed upon reaction between ninhydrin and 1,3,5-benzenetriol was first reported by Kim The molecular structure of the bis ninhydrin naphthalene-1,3-diol [1] complex with CsOAc showing 50% probability ellipsoids for non-H atoms. Hydrogen bonding is represented by the orange dashed lines. Aromatic H atoms have been omitted for clarity. The codes for symmetry-related atoms are given in Table 1.

Figure 1
The molecular structure of the bis ninhydrin naphthalene-1,3-diol ligand [1], showing 50% probability ellipsoids for non-H atoms. Solvent molecules and the Cs I ion have been omitted for clarity. Table 1 Hydrogen-bond geometry (Å , ). and his co-workers (Na et al., 2005), while other groups attempted similar reactions involving ninhydrin and polyhydroxy aromatics (Kundu et al., 2004;Mahmood et al., 2011). Since then, the reaction has been thoroughly explored by our group, expanding the family of these ligands, which we have named vasarenes (Almog et al., 2009;Gil et al., 2014;Bengiat et al., 2016c,d). A comprehensive study of the supramolecular reactions of the vasarenes and their analogues with M + F À salts has also been carried out (Almog et al., 2012;Bengiat et al., 2016a,b,c). However, this is the first time that a complex with an anion other than fluoride has been reported. A fragment of the crystal packing of the [1]ÁCsOAc complex showing the parallel-displacedstacking with an interplanar distance of 3.669 Å at 50% probability ellipsoids for non-H atoms. Aromatic H atoms and solvent molecules have been omitted for clarity.

Figure 4
The crystal packing of the [1]ÁCsOAc complex showing 2 Â 2 Â 2 unit cells. Aromatic H atoms and solvent molecules have been omitted for clarity.

Figure 5
The crystal packing of the complex of bis ninhydrin 1,3-benzenediol with CsF (Bengiat et al., 2016b) showing 2 Â 2 Â 2 unit cells. Aromatic H atoms and solvent molecules have been omitted for clarity.
addition of the CsF solution an immediate color change to intense yellow was observed, later changing to bright orange. The mixture was left to crystallize at RT for a few days, forming a colorless crystalline precipitate suitable for single crystal X-ray diffraction.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Hydroxyl H atoms of the ligand molecules and H atoms of the EtOH molecule were located in a different Fourier map and all H-atom parameters refined.
Other H atoms were placed in calculated positions with C-H = 0.95 (aromatic), 0.99 (methylene) and 0.98 Å (methyl), and refined in riding mode with U iso (H) = 1.2U eq (C) for aromatic and aliphatic H atoms and 1.5U eq (C) for the methyl H atoms. program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.007 Δρ max = 1.72 e Å −3 Δρ min = −0.66 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.