Sodium cobaltinitrite

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Sodium cobaltinitrite
Sodium cobaltinitrite.png
Sodium cobaltinitrite powder.jpg
IUPAC name
sodium hexanitrocobaltate(III)
3D model (JSmol)
ECHA InfoCard 100.033.692
Molar mass 403.933 g·mol−1
Density 2.565 g/cm3
Safety data sheet JT Baker MSDS
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 cobaltinitrite is inorganic compound with the formula Na3Co(NO2)6. The anion of this yellow-coloured salt consists of the coordination complex [Co(NO2)6]3-. It was a reagent for the qualitative test for potassium and ammonium ions.[1]

Synthesis and reactions[edit]

The compound is prepared by oxidation of cobalt(II) salts in the presence of sodium nitrite:[2]

4 [Co(H2O)6](NO3)2 + O2 + 24 NaNO2 → 4 Na3[Co(NO2)6] + 8 NaNO3 + 4 NaOH + 22 H2O

Application for analysis of potassium[edit]

Although the sodium cobaltinitrite is soluble in water, it forms the basis of a quantitative determination of potassium, thallium, and ammonium ions. Under the recommended reaction conditions the insoluble double salt, K2Na[Co(NO2)6]·H2O is precipitated and weighed.[3] In geochemical analysis, sodium cobaltinitrite is used to distinguish alkali feldspars from plagioclase feldspars in thin section.[4]

Fragment of the Na3Co(NO2)6 lattice, highlighting the CoN6 and NaO6 coordination spheres.[5]

See also[edit]


  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  2. ^ Glemser, O. (1963). "Sodium Hexanitritocobaltate(III)". In Brauer, G. (ed.). Handbook of Preparative Inorganic Chemistry. 1 (2nd ed.). New York, NY: Academic Press. p. 1541.
  3. ^ Vogel, A. I. (1951). Quantitative Inorganic Analysis (2nd ed.). Longmans Green and Co.
  4. ^ Bailey, E. H.; Stevens, R. E. (1960). "Selective staining of K-feldspar and plagioclase on rock slabs and thin sections". American Mineralogist. 45: 1020–1025.
  5. ^ Brian N. Figgis, Alexandre N. Soboleva (2001). "Na3Co(NO2)6 at 293 and 10 K". Acta Crystallographica Section C. 57: 885–886. doi:10.1107/S0108270101007995.CS1 maint: Uses authors parameter (link)