Abstract
The title compound, NaK5Cl2(S2O6)2 [systematic name: sodium penta-potassium dichloride bis-(di-thio-nate)], arose as an unexpected product from an organic synthesis that used di-thio-nite (S2O42-) ions as a reducing agent to destroy excess permanganate ions. Compared to the previous study [Stanley (1953 ▸). Acta Cryst.6, 187-196], the present tetra-gonal structure exhibits a root 2a × root 2a × c super-cell due to subtle changes in the orientations of the di-thio-nate anions. The structure can be visualized as a three-dimensional framework of [001] columns of alternating trans-NaO4Cl2 and KO4Cl2 octa-hedra cross-linked by the di-thio-nate ions with the inter-stices occupied by KO6Cl2 polyhedra to generate a densely packed three-dimensional framework. The asymmetric unit comprises 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-di-thio-nate ions (all atoms on general positions). Both di-thio-nate 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.
Highlights
The title compound, NaK5Cl2(S2O6)2 [systematic name: sodium pentapotassium dichloride bis(dithionate)], arose as an unexpected product from an organic synthesis that used dithionite (S2O42) ions as a reducing agent to destroy excess permanganate ions
The structure can be visualized as a three-dimensional framework of [001] columns of alternating trans-NaO4Cl2 and KO4Cl2 octahedra cross-linked by the dithionate ions with the interstices occupied by KO6Cl2 polyhedra to generate a densely packed three-dimensional framework
= 4, 4, 1 and 1), three chloride ions and two halfdithionate ions. Both dithionate ions are completed by crystallographic inversion symmetry
Summary
As well as their large-scale industrial use in reducing and solublizing vat dyes such as indigo (Božič & Kokol, 2008), dithionites containing the S2O42 anion The title mixed-cation, mixed-anion compound, NaK5Cl2(S2O6) (I), containing S2O62 dithionate ions (sulfur oxidation state = +5), arose as a completely unexpected side product from an attempt to oxidize hexamethyl 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 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), was established over 60 years ago (Stanley, 1953). The structure of the title compound, along with that of the non-isostructural Na2K4Cl2(S2O6), was established over 60 years ago (Stanley, 1953) This re-determination presents a superstructure of the earlier reported structure, which arises from subtle orientational changes for the dithionate anions
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