Crystal structure of sodium (1S)-d-lyxit-1-ylsulfonate

The anion has an open-chain structure in which one of the oxygen atoms of the sulfate residue, the S atom, the C atoms of the sugar chain and the O atom of the hydroxymethyl group form an essentially planar zigzag chain. A three-dimensional bonding network exists in the crystal structure involving hexacoordination of sodium ions by O atoms, three of which are provided by a single d-lyxose–sulfonate unit and the other three by two sulfonate groups and one hydroxymethyl group, each from separate units of the adduct. Extensive intermolecular O—H⋯O hydrogen bonding supplements this bonding network.


Chemical context
Bisulfite adducts of aldehydes are important compounds because, in many cases, they are crystalline and allow a means of purification and storage of those aldehydes which are liquids or which suffer from problems of instability. The importance of aldehydes in many synthetic processes for the production of commercially important compounds, including pharmaceuticals, means that there is continuing interest in these bisulfite adducts. A recent publication (Kissane et al., 2013) has focused on counter-ion effects in the preparation of aldehyde-bisulfite adducts. Of particular concern in that work was a comparison of the physical properties of sodium and potassium bisulfite adducts of a range of aldehydes, to include their hygroscopic nature and ease of filtration, in order to facilitate their preparation and storage on a large scale. Studies by X-ray crystallography on the bisulfite adducts of common aldehydo-sugars such as d-glucose (Cole et al., 2001) and our related work on d-galactose (Haines & Hughes, 2010), d-ribose (Haines & Hughes, 2014) and d-lyxose (Haines & Hughes, 2015) indicated the crystallinity and ease of isolation of such potassium adducts, and also, in the case of the sodium bisulfite adduct of d-glucose (Haines & Hughes, 2012), allowed a comparison of the potassium and sodium Schematic representation of the preparation of the title compound. compounds. We now report the preparation (Fig. 1), properties, and crystal structure of the sodium bisulfite adduct of d-lyxose, which allows a further comparison of the influence of the two counter-ions in the properties of an adduct from the same substrate.
Crystallization of the sodium bisulfite adduct of d-lyxose from water required a very concentrated solution from which highly crystalline material grew slowly on storage at room temperature. In contrast to the potassium adduct (Haines & Hughes, 2015), the crystals lacked water of crystallization but had the same S-configuration at C1, leading to a similar positive optical rotation for the two products. The melting points of the sodium and potassium adducts (417.6-420.1 K and 392-400 K, respectively, both with decomposition) were above that of d-lyxose (381-385 K). Both of the d-lyxose adducts were stable on storage in a sealed container at room temperature.

Structural commentary
The newly formed chiral centre at C1 has the S-configuration (Fig. 2) and the systematic name for the salt is sodium (1S,2S,3S,4R)-1,2,3,4,5-pentahydroxypentane-1-sulfonate. The anion has an open-chain structure in which one of the oxygen atoms, O13, of the sulfonate residue, the S atom, the C atoms of the sugar chain and the oxygen atom, O5, of the terminal hydroxymethyl group form an essentially planar zigzag (alltrans) chain with the corresponding torsion angles lying between the absolute values of 179.80 (11) and 167.74 (14) . The atoms O13-C4 form a plane, with C5 and O5 displaced 0.229 (3) and 0.525 (2) Å , respectively, from that mean plane. All of the hydroxyl groups form medium-strength to weak intermolecular hydrogen bonds which connect molecules in an extensive three-dimensional network ( Fig. 3 and Table 1). This network is enhanced through complexation of the sodium atom which has a coordination sphere of six oxygen atoms with an approximately octahedral pattern in which three sites are occupied by oxygen atoms O1, O2, and O11 of one basic dlyxose-sulfonate unit and the remaining three sites are occupied by oxygen atoms O12 and O13 arising from two different sulfonate groups, and O5 of another d-lyxose-sulfonate unit. View of the d-lyxose-NaHSO 3 adduct, indicating the atom-numbering scheme, all sodium coordination contacts and hydrogen bonds involving the atoms of the basic adduct moieties. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (1) x, y, z À 1; (2) x, y + 1, z; (3) x À 1, y + 1, z; (4) x, y À 1, z; (5) x + 1, y À 1, z; (6) x, y, z + 1; (7) x À 1, y, z + 1; (8) x À 1, y, z; (9) x + 1, y, z.] Table 1 Hydrogen-bond geometry (Å , ).

Figure 3
View approximately along the d-lyxose chain, showing the intermolecular hydrogen bonding and coordination links. Symmetry codes are as in Fig. 2.
2.5265 (16) Å . The sodium atoms are linked in planes parallel to the ab plane through coordinating sulfonate groups supported by H-OÁ Á ÁNa coordination and hydrogen bonds (Fig. 4). There is no symmetry in this space group; all the molecules lie parallel and are arranged by translation parallel to the cell axes. A comparison of the crystal structures of the sodium and potassium bisulfite adducts of d-lyxose illustrates the different coordination requirements of the two alkali metal cations. In the potassium salt hydrate (Haines & Hughes, 2015), two distinct environments for the cation are observed, involving both hexa-and octa-coordination of oxygen atoms, with each cation lying on a twofold symmetry axis. Oxygen atoms from the water of crystallization provide two of the coordination sites for the octa-coordinate potassium ion. In contrast, the sodium salt lacks water of crystallization and possesses a much simpler crystal structure having one environment only for the cation with hexa-coordination of oxygen atoms. However, in both cases the structures accommodate a nearly planar zigzag chain incorporating the sulfur atom, the five sugar carbon atoms and the oxygen of the terminal hydroxymethyl group, and both adducts crystallize with the same S-configuration at the newly formed chiral centre, despite evidence for the existence of the R-stereoisomer in solution.

Supramolecular features
A three-dimensional bonding network exists in the crystal structure through (i) hexa-coordination of a sodium cation with oxygens from four different lyxose bisulfite residues, three of those oxygens coming from one such residue, and (ii) intermolecular hydrogen bonds from each of the five hydroxyl groups to acceptor oxygens in four different residues.

Spectroscopic findings
High resolution mass spectrometry in negative ion mode showed no peak for ([C 5 H 11 O 8 S 1 ] À ) at m/z 231.0108 but a significant peak was observed at 213.0075 ([C 5 H 11 O 8 S 1 -H 2 O] À ). The mono-anion of d-lyxose gave a peak at m/z 149.0458 ([C 5 H 9 O 5 ] À ) and the base peak of the spectrum, observed at m/z 299.0982 ([C 10 H 19 O 10 ] À ), was assigned to a dimer ion ([2M -H] À ) produced by association of a d-lyxose molecule (M = C 5 H 10 O 5 ) with the mono-anion of d-lyxose ([C 5 H 9 O 5 ] À ) under the electrospray ionization conditions of the mass spectrometric measurement.
The 1 H NMR spectrum of the adduct in D 2 O indicated the presence of theand -pyranose forms of d-lyxose and the major and minor forms of the acyclic sulfonate in the % ratios 11.62 : 5.47 : 74.78 : 8.14. Clearly, the R-stereoisomer at C1 is present in solution but only the S-isomer crystallizes. Further, some hydrolysis of the adduct to afford the parent sugar occurs during the NMR measurement. As expected, the NMR spectrum of the sodium bisulfite adduct is very similar to that of the related potassium sulfite adduct reported earlier (Haines & Hughes, 2015).
The 13 C NMR spectrum showed signals for C1 nuclei at C 94.81, 94.68, 84.21 and 82.17 arising, respectively, from theand -pyranose forms of d-lyxose, the minor adduct and the major adduct, in the % ratios of 5 View approximately onto the ab plane, showing the links between the sodium ions parallel to that plane. Symmetry codes are as in Fig. 2.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms were located in difference maps and were refined freely with isotropic displacement parameters, except for H1 and H3 for which the U iso values were set at the positive value of 0.010 (rather than refining to a very low or negative value).

Special details
Experimental. Absorption correction: CrysAlisPro (Agilent 2014). Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. 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.