Sodium thioantimoniate

Sodium thioantimoniate

Names
IUPAC name Sodium tetrathioantimonate(V)
Properties
Chemical formula	Na3SbS4·9H2O
Appearance	Yellow crystals
Density	1.806 g/cm^3, solid
Melting point	87 °C (189 °F; 360 K)
Related compounds
Other anions	Potassium thioantimoniate
Related compounds	Antimony(III) sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sodium thioantimoniate is an inorganic compound with the formula Na₃SbS₄. The nonahydrate of this material is known as Schlippe's salt, named after K. F. Schlippe (1799–1867), These compounds are examples of sulfosalts. They are mainly of historic interest.

Structure

This hydrated salt consists of the tetrahedral SbS₄³⁻ anion (r_Sb-S = 2.33 Å) and sodium cations, which are hydrated.^[1][2] Related salts are known for different cations including ammonium and potassium.

The anhydrous salt is polymer with tetrahedral Na and Sb sites.^[3]

Preparation

Sodium thioantimoniate is prepared by the reaction of antimony trisulfide, elemental sulfur, and aqueous sulfide source.

3 Na₂S + 2 S + Sb₂S₃ + 9 H₂O → 2 Na₃SbS₄·9 H₂O

The sulfide can be generated indirectly by the thermal reaction of elemental sulfur with sodium hydroxide or even charcoal:

Sb₂S₃ + 8 NaOH + 6 S → 2 Na₃SbS₄ + Na₂SO₄ + 4 H₂O

In the latter route, a mixture of sodium sulfate (16 parts) is reduced by fusion with charcoal (4-5 parts) in the presence of antimony sulfide (13 parts). The melt is extracted into water which is treated with sulfur (4 parts). Upon evaporation of the solution, the salt crystallizes as large tetrahedra, which are easily soluble in water. The anhydrous salt melts easily on heating, and in the hydrated condition, on exposure to moist air becomes coated with a red film.

The required antimony(III) sulfide is prepared in the usual way by treatment of virtually any Sb(III) compound with sulfide sources:

2 SbCl₃ + 3 H₂S → Sb₂S₃ + 6 HCl

Reactions

The hydrate dissolves in water to give the tetrahydral SbS₄^3- ion. The salt gives "quinsulfide antimony," upon acidification:

2 Na₃SbS₄ + 6 HCl → Sb₂S₅ + 6 NaCl + 3 H₂S

Related compounds

• Antimony (III) sulfide, Sb₂S₃

Notes

1. Krebs, B., "Thio- and Seleno Compounds of Main Group Elements - New Inorganic Oligomers and Polymers", Angewandte Chemie, 1983, volume 95, pages 113-34.
2. K. Mereiter, A. Preisinger and H. Guth "Hydrogen bonds in Schlippe's salt: refinement of the crystal structures of Na₃SbS₄^.9H₂O by X-ray diffraction and Na₃SbS₄^.9D₂O by neutron diffraction at room temperature" Acta Crystallographica 1979, vol. B35, 19-25. doi:10.1107/S0567740879002442.
3. H. A. Graf, H. Schäfer "Zur Strukturchemie der Alkalisalze der Tetrathiosäuren der Elemente der 5. Hauptgruppe (pages 67–80) Zeitschrift fuer Anorganische und Allgemeine Chemie 1976, vol. 425, p67-p80. doi:10.1002/zaac.19764250109

References

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Schlippe's Salt". Encyclopædia Britannica (11th ed.). Cambridge University Press.