Sodium hexanitritocobaltate(III)

Sodium hexanitritocobaltate(III) is an inorganic compound with the formula Na₃[Co(NO₂)₆]. The anion of this yellow-coloured salt consists of the transition metal nitrite complex [Co(NO₂)₆]³⁻. It was a reagent for the qualitative test for potassium and ammonium ions.^[2]

Sodium hexanitritocobaltate(III)

Names
IUPAC name Sodium hexanitritocobaltate(III)
Other names Sodium cobaltinitrite
Identifiers
CAS Number	13600-98-1 Y
3D model (JSmol)	Interactive image
ChemSpider	13198283 Y
ECHA InfoCard	100.033.692
EC Number	237-077-7
PubChem CID	16211641
UNII	XO0NGY9EY7 Y
CompTox Dashboard (EPA)	DTXSID00894906
InChI InChI=1S/Co.6NO2.3Na/c;6*2-1-3;;;/q-3;;;;;;;3*+1 Y Key: IMBXIBFCGMYSME-UHFFFAOYSA-N Y InChI=1/Co.6NO2.3Na/c;6*2-1-3;;;/q-3;;;;;;;3*+1/rCoN6O12.3Na/c8-2(9)1(3(10)11,4(12)13,5(14)15,6(16)17)7(18)19;;;/q-3;3*+1 Key: IMBXIBFCGMYSME-PEVTYUNUAJ
SMILES [Na+].[Na+].[Na+].O=[N+]([O-])[Co-3]([N+]([O-])=O)([N+](=O)[O-])([N+]([O-])=O)([N+]([O-])=O)[N+]([O-])=O
Properties
Chemical formula	Na3[Co(NO2)6]
Molar mass	403.933 g·mol−1
Appearance	Yellow crystals
Density	2.565 g/cm3
Hazards
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H272, H315, H317, H319, H334, H335, H351
Safety data sheet (SDS)	JT Baker MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Synthesis and reactions

The compound is prepared by oxidation of cobalt(II) salts in the presence of sodium nitrite:^[3]

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

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.^{[4][page needed]} In geochemical analysis, sodium cobaltinitrite is used to distinguish alkali feldspars from plagioclase feldspars in thin section.^[5]

• 
  Concentrated aqueous solution of sodium cobaltinitrite.
• 
  K₂Na[Co(NO₂)₆]·H₂O

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

See also

• Potassium hexanitritocobaltate(III)