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research communications An unexpected oxidation: NaK5Cl2(S2O6)2 revisited William T. A. Harrison* and M. John Plater ISSN 2056-9890 Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland. *Correspondence e-mail: [email protected] The title compound, NaK5Cl2(S2O6)2 [systematic name: sodium pentapotassium Received 4 January 2017 dichloride bis(dithionate)], arose as an unexpected product from an organic Accepted 10 January 2017 2À synthesis that used dithionite (S2O4 ) ions as a reducing agent to destroy excess permanganate ions. Compared to the previous study [Stanleyp (1953).p Acta Cryst. Edited by M. Weil, Vienna University of 6, 187–196], the present tetragonal structure exhibits a 2a  2a  c super- Technology, Austria cell due to subtle changes in the orientations of the dithionate anions. The structure can be visualized as a three-dimensional framework of [001] columns Keywords: crystal structure; dithionate; super- of alternating trans-NaO4Cl2 and KO4Cl2 octahedra cross-linked by the cell; redetermination. dithionate ions with the interstices occupied by KO6Cl2 polyhedra to generate a densely packed three-dimensional framework. The asymmetric unit comprises CCDC reference: 1526611 two sodium ions (site symmetries 4 and 4), four potassium ions (site symmetries = 4, 4, 1 and 1), three chloride ions (site symmetries = 4, 4 and 2) and two half- Supporting information: this article has supporting information at journals.iucr.org/e dithionate ions (all atoms on general positions). Both dithionate ions are completed by crystallographic inversion symmetry. The crystal chosen for data collection was found to be rotationally twinned by 180 about the [100] axis in reciprocal space with a 0.6298 (13):0.3702 (13) domain ratio. 1. Chemical context As well as their large-scale industrial use in reducing and solublizing vat dyes such as indigo (Bozˇicˇ & Kokol, 2008), 2À dithionites containing the S2O4 anion (sulfur oxidation state = +3) have long found use as moderately strong reducing agents in organic synthesis (De Vries & Kellogg, 1980, and references therein). The title mixed-cation, mixed-anion 2À compound, NaK5Cl2(S2O6)2 (I), containing S2O6 dithionate ions (sulfur oxidation state = +5), arose as a completely unexpected side product from an attempt to oxidize hexa- methyl benzene to mellitic acid as a precursor of synthetic mellite (Plater & Harrison, 2015): sodium dithionite was added to the reaction to destroy excess permanganate ions (as KMnO4) and the source of the chloride ions was added HCl. To our slight surprise, the structure of the title compound, along with that of the non-isostructural Na2K4Cl2(S2O6)2, was established over 60 years ago (Stanley, 1953). This re-deter- mination presents a superstructure of the earlier reported structure, which arises from subtle orientational changes for the dithionate anions. 2. Structural commentary Compound (I) comprises two sodium ions (Na1 site symmetry = 4, Na2 site symmetry = 4), four potassium ions (site symmetries = 4, 4, 1 and 1 for K1, K2, K3 and K4, respec- tively), three chloride ions (Cl1 and Cl2 with site symmetry 4, Cl3 with site symmetry 2) and two half-dithionate ions (all atoms on general positions) in the asymmetric unit. Selected 188 https://doi.org/10.1107/S2056989017000494 Acta Cryst. (2017). E73, 188–191 research communications Table 1 Selected bond lengths (A˚ ). Na1—O1i 2.3375 (13) K3—Cl2 3.1088 (5) Na1—Cl1ii 2.6942 (13) K4—O2viii 2.8429 (11) Na1—Cl2 2.7260 (12) K4—O6vi 2.9235 (11) Na2—O5iii 2.3506 (13) K4—O6ix 2.9941 (11) Na2—Cl3iv 2.6986 (5) K4—O4x 3.0284 (12) K1—O3v 2.8262 (12) K4—O3xi 3.0290 (11) K1—Cl3iv 2.9976 (5) K4—O2xii 3.0664 (12) K2—O6 2.8193 (11) K4—Cl1 3.1168 (5) K2—Cl2 2.9746 (8) K4—Cl3x 3.1291 (5) K2—Cl1 2.9978 (9) S1—O3 1.4465 (11) K3—O4v 2.7843 (11) S1—O2 1.4507 (10) K3—O2v 2.8705 (11) S1—O1 1.4526 (13) K3—O4vi 2.8973 (11) S1—S1i 2.1227 (9) K3—O3i 2.8995 (11) S2—O6 1.4475 (11) K3—O1vii 2.9148 (11) S2—O5 1.4505 (13) K3—O5iii 3.0176 (11) S2—O4 1.4516 (10) K3—Cl3iv 3.0836 (5) S2—S2xiii 2.1176 (9) 1 1 Symmetry codes: (i) Àx þ 1; Ày þ 1; Àz; (ii) x; y; z À 1; (iii) x þ 2; y À 2; Àz þ 1; (iv) 3 1 1 1 1 Ày þ 2; x; z; (v) y; Àx þ 2; z; (vi) Àx þ 2; Ày þ 2; z; (vii) Ày þ 1; x À 2; Àz; (viii) 1 1 1 Ày þ 1; x À 2; Àz þ 1; (ix) Ày þ 2; x; z; (x) y À 2; Àx; Àz þ 1; (xi) 1 1 1 1 Àx þ 2; Ày þ 2; z þ 1; (xii) x À 2; y À 2; Àz þ 1; (xiii) Àx; Ày þ 1; Àz þ 1. Figure 2 2À geometrical data are given in Table 1. Both S2O6 dithionate View down [001] of a slice (0.35 z 0.65) of the structure of (I). ions are completed by crystallographic inversion symmetry at Displacement ellipsoids are displayed at the 50% probability level. the mid-points of their S—S bonds [S1—S1i = 2.1227 (9), S2— [Symmetry codes: (ii) Àx,1À y,1À z; (iii) 1 À x,1À y,1À z.] Note that K2 lies on a fourfold axis and Na2 has 4 site symmetry. S2xiii = 2.1176 (9) A˚ ; see Table 1 for symmetry codes] and both exhibit almost ideal staggered conformations about their S—S bond deviates from the (001) plane by 12.5 and the S2—O5 bonds. The mean S—O bond length (both unique ions) is 1.45 A˚ and the narrow spread of individual S—O bond lengths bond deviates by 10.6 (vide infra). from 1.4465 (11) to 1.4526 (13) A˚ indicates that the negative The packing for (I) can be described in terms of pseudo charges of the anion are delocalized over the three O atoms layers lying perpendicular to the c-axis direction of the attached to each S atom (i.e.: we cannot identify localized tetragonal unit cell. At z 0 and 1, the S1/O1/O2/O3 di- S O double bonds and S—O single bonds). In terms of the orientation of the dithionate ions in the unit cell, the S1—O1 Figure 3 View down [001] of a slice (0.25 z 0.35) of the structure of (I). Displacement ellipsoids are displayed at the 50% probability level. 3 1 Figure 1 [Symmetry codes: (iii) 1 À x,1À y,1À z; (iv) 2 À y, x, z; (v) 2 À y, x, z; (vi) 1 1 1 View down [001] of a slice (À0.15 z 0.15) of the structure of (I). 2 + y,1À x,1À z; (vii) 2 + x, 2 + y,1À z.] Note that Cl1 and Cl2 lie on Displacement ellipsoids are displayed at the 50% probability level. fourfold axes and Cl3 lies on a twofold axis. The chloride ions link to the [Symmetry code: (i) 1 À x,1À y, Àz.] Note that Na1 lies on a fourfold sodium and potassium ions shown in Figs. 1 and 2 to generate infinite axis and K1 has 4 site symmetry. stacks of alternating NaO4Cl2 and KO4Cl2 octahedra. Acta Cryst. (2017). E73, 188–191 Harrison and Plater NaK5Cl2(S2O6)2 189 research communications Table 2 Experimental details. Crystal data Chemical formula NaK5Cl2(S2O6)2 Mr 609.63 Crystal system, space group Tetragonal, P4/n Temperature (K) 100 a, c (A˚ ) 12.0421 (1), 11.3925 (2) V (A˚ 3) 1652.05 (4) Z 4 Radiation type Mo K (mmÀ1) 2.24 Crystal size (mm) 0.05  0.02  0.02 Data collection Diffractometer Rigaku Mercury CCD Absorption correction Multi-scan (SADABS; Sheldrick, 2004) Tmin, Tmax 0.911, 1.000 No. of measured, independent and 1910, 1910, 1834 Figure 4 observed [I >2(I)] reflections ˚ À1 Polyhedral view of the structure of (I), showing the [001] chains of (sin /)max (A ) 0.649 NaO4Cl2 octahedra (blue) and KO4Cl2 (K1 and K2) octahedra (lilac) cross-linked by the dithionate groups. Atoms K3 and K4 are shown as Refinement 2 2 2 purple spheres. R[F >2(F )], wR(F ), S 0.015, 0.043, 1.06 No. of reflections 1910 No. of parameters 113 ˚ À3 thionate ion and the Na1 and K1 cations reside (Fig. 1); at Ámax, Ámin (e A ) 0.35, À0.35 z 1/2, are to be found the S2/O4/O5/O6 dithionate ion and Computer programs: CrystalClear (Rigaku, 2010), SHELXT (Sheldrick, 2015a), Na2 and K2 (Fig. 2). Between them, at z 1/4 and 3/4, are K3, SHELXL2014 (Sheldrick, 2015b), ORTEP-3 for Windows (Farrugia, 2012) and ATOMS K4 and the three chloride ions, which form a distorted square (Dowty, 1999). grid (Fig. 3). The extended structure of (I) can be visualized (Fig. 4) as them as not significant. The three chloride ions each adopt [001] chains of alternating trans-NaO4Cl2 and KO4Cl2 octa- almost regular ClK5Na octahedral geometries. hedra linked via their chloride ions and cross-linked by the Bond-valence sum (BVS) data (Brown & Altermatt, 1985) dithionate groups. There are two distinct chains: the Na1 and for the cations in (I) indicate that the sodium ions in (I) are K2 species and their linking chloride ions (Cl1 and Cl2) lie on considerably ‘overbonded’: BVS(Na1) = 1.46 and BVS(Na2) = the fourfold axes at (1/4, 1/4, z) and (3/4, 3/4, z), whereas Na2 1.45 (expected value = 1.0 valence units).
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  • List of Spectra /Compound Names

    List of Spectra /Compound Names

    IS NIR Spectra Complete collection (6049 spectra) This collection includes all NIR spectra collected within this project. Those are organic and inorganic chemicals, pharmaceutical excipients, drugs, polymers, additives, coatings, dyes, pigments, toxic substances, hazardous substances like explosives, agrochemicals and other types of materials. This collection should be chosen by customers with broad range of analytical applications. The near infrared spectral library „IS NIR Spectra“ is a unique collection of 6049 NIR (near infrared) digital spectra. The spectra have been collected in range 4200-10000 cm-1 (=2.4 – 1 micrometers). „IS NIR Spectra“ is the biggest and newest NIR library available on the market. This spectral library has been designed for users who use their NIR spectrometer not only for quantitative and chemometric analysis, but also want to identify unknown samples or just want to use the library as reference spectra database. ra t IS means “Intergrating Sphere” and at the same time “Identify Samplec”. e Technical parameters: p The „IS NIR Spectra“ were collected using the FT-NIR Spectrometer equipped with Integrating Sphere Accessory. Resolution: standard 4cm-1 IR Customized resolution: upon special request the speNctra can be delivered in customized resolution to reach better correspondence with spectr a collected by customer NIR instrument Spectral range in wavenumbers units: 4200-1000I0S cm-1 Spectral range in wavelength units: 2.4 – 1 micr ometers Only one spectrum/compound covering the mentioned spectral range Typical text information about the sample inmcludes (when available): Compound name including synonyms o CAS number .c Chemical formula a Molecular weight tr Additional information about thec sample like manufacturer and comments.