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Potassium cobaltinitrite, IUPAC name potassium hexanitritocobaltate(III), is a salt with the formula K3[Co(NO2)6]. It is a yellow solid that is insoluble in water. The compound finds some use as a yellow pigment.

Potassium cobaltinitrite
Potassium cobaltinitrite.svg
Cobalt yellow.jpg
IUPAC name
Potassium hexanitritocobaltate(III)
3D model (JSmol)
ECHA InfoCard 100.034.018
K3[Co(NO2)6] (anhydrous)
K3[Co(NO2)6]·1.5H2O (sesquihydrate)
Molar mass 452.26 g/mol (anhydrous)
479.284 g/mol (sesquihydrate)
Appearance yellow cubic crystals (sesquihydrate)
Density 2.6 g/cm3 (sesquihydrate)
slightly soluble in water (sesquihydrate)
Solubility reacts with acids, insoluble in ethanol (sesquihydrate)[1]
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

The salt features potassium cations and an trianionic coordination complex. In the anion, cobalt is bound by six nitrito ligands, the overall complex having octahedral molecular geometry. The oxidation state of cobalt is 3+. Its low-spin d6 configuration confers kinetic stability and diamagnetism.

The compound was first described in 1848 by Nikolaus Wolfgang Fischer in Breslau,[2] and it is used as a yellow pigment called Aureolin.[3][4]

See alsoEdit


  1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 4–54. ISBN 0-8493-0594-2
  2. ^ Fischer, N. W. (1848). "Ueber die salpetrichtsauren Salze". Annalen der Physik und Chemie. 150 (5): 115–125. Bibcode:1848AnP...150..115F. doi:10.1002/andp.18491500512.
  3. ^ Gates, G. (1995). "A Note on the Artists' Pigment Aureolin". Studies in Conservation. 40 (3): 201–206. doi:10.2307/1506479. JSTOR 1506479.
  4. ^ Gettens, Rutherford John; Stout, George Leslie (1966). Painting materials: A short encyclopaedia. pp. 109–110. ISBN 978-0-486-21597-6.