Hyponitrite

Hyponitrite

Names
Preferred IUPAC name Hyponitrite
Systematic IUPAC name Oxidoazanylidene
Identifiers
Abbreviations	NO((2.)-)
ChEBI	CHEBI:29121
ChemSpider	2272768
Jmol interactive 3D	Image
PubChem	3001380
InChI InChI=1S/NO/c1-2/q-1 Key: FZRKAZHKEDOPNN-UHFFFAOYSA-N
SMILES [N-]=O
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

Bis(hyponitrite)

Names
Preferred IUPAC name Hyponitrite
Systematic IUPAC name Diazenebis(olate)
Other names Hyponitrite(2-)
Identifiers
3DMet	B00354
ChEBI	CHEBI:18210
ChemSpider	3874228 ()
Gmelin Reference	130273
Jmol interactive 3D	Image
KEGG	C01818
PubChem	6185901 (E) 4686309 ()
InChI InChI=1S/H2N2O2/c3-1-2-4/h(H,1,4)(H,2,3)/p-2 Key: NFMHSPWHNQRFNR-UHFFFAOYSA-L
SMILES [O-]N=N[O-]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

A hyponitrite refers to ionic compounds that contain the hyponitrite ion, N
2O2−
2, ([ON=NO]²⁻) or to organic hyponitrites (RON=NOR), for example di-tert butyl hyponitrite.

Hyponitrite ion

There are cis and trans forms of the hyponitrite ion.^[1] The trans form is generally found in hyponitrite salts such as sodium hyponitrite, Na₂N₂O₂ and silver hyponitrite, Ag₂N₂O₂. The trans-isomer is conventionally prepared by nitrite reduction with sodium amalgam.^[2][3] Sodium hyponitrite can be prepared from sodium and nitric oxide by a method described by an earlier method modified with pyridine, from sodium amalgam and sodium nitrite, from alkyl nitrites and hydroxylamine^[4] or by electrolysis of sodium nitrite.^[5]

The cis-isomer of the sodium salt, NaN₂O₂, can be prepared by passing nitrous oxide, NO into a solution of sodium metal in liquid ammonia at −50 °C.^[1]The cis salt is more reactive than the trans. The trans-hyponitrite ion is a salt of the related trans-hyponitrous acid H₂N₂O₂ ( HON=NOH ), the cis acid is not known.^[1]
The hyponitrite ions can act as a bidentate ligand in either bridging or chelating mode. There is a bridging cis-hyponitrite group in the red dinuclear form of nitrosyl pentammine cobalt(III) chloride, [Co(NH₃)₅NO]Cl₂.^[6]
Hyponitrite can act as a reducing agent for example reducing iodine, I₂,:^[6]

N
2O2−
2 + 3I₂ + 3H₂O = NO−
3 + NO−
2 + 6HI

Liquid N₂O₄ oxidises hyponitrites to give Na₂N₂O₃, sodium peroxohyponitrite (containing [ON=NOO]²⁻).^[1]

Hyponitrous acid

Trans-hyponitrous acid forms white crystals that are explosive when dry. It is a weak acid in aqueous solution and decomposes to N₂O and water with a half life of 16 days at 25 °C at pH 1–3.^[1] As this reaction is not reversible N₂O should not be considered as the anhydride of H₂N₂O₂.^[1] Hyponitrous acid forms salts, the "acid hyponitrites" containing the [HON=NO]⁻ anion as well as the hyponitrites that contain the [ON=NO]²⁻ anion.^[1]

Other nitrogen oxoanions

Other nitrogen oxoanions include

• nitrate, NO−
  3
• nitrite, NO−
  2
• peroxonitrite, (peroxynitrite), OONO⁻
• peroxonitrate, HNO−
  4
• trioxodinitrate, (hyponitrate), [ON=NO₂]²⁻
• nitroxylate, [O₂N−NO₂]⁴⁻
• orthonitrate NO3−
  4
• dinitramide[O₂N–N–NO₂]⁻
• nitrosyl hyponitrite[ONNONO]⁻

Alkyl hyponitrites

Silver hyponitrite reacts with alkyl halides, RX, to form organic hyponitrites, (RON=NOR), e.g. trans-t-butyl hyponitrites.^[7] One use of these is as a source of alkoxyl radicals.^[8]

References

1. Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
2. Addison, C. C.; Gamlen G. A.; Thompson, R. (1952). "70. The ultra-violet absorption spectra of sodium hyponitrite and sodium α-oxyhyponitrite : the analysis of mixtures with sodium nitrite and nitrate". J. Chem. Soc.: 338. doi:10.1039/jr9520000338.
3. Neumann, R. C., Jr. Bussey, R. J. (1970). "High pressure studies. V. Activation volumes for combination and diffusion of geminate tert-butoxy radicals". J. Am. Chem. Soc. 92 (8): 2440. doi:10.1021/ja00711a039.
4. Scott, A. W. (1927). J. Am. Chem. Soc. 49 (4): 986–7. doi:10.1021/ja01403a502. Missing or empty |title= (help)
5. Polydoropoulos, C. N. Chem. Ind. (London) 1963, 1686 and references therein.
6. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
7. Navamoney Arulsamy, D. Scott Bohle, Jerome A. Imonigie, Elizabeth S. Sagan (2000). "Correlation of the Product E/Z Framework Geometry and O/O vs O/N Regioselectivity in the Dialkylation of Hyponitrite". J. Am. Chem. Soc. 122 (23): 5539–5549. doi:10.1021/ja994261o.
8. Craig A. Ogle, Steven W. Martin, Michael P. Dziobak, Marek W. Urban, G. David Mendenhall (1983). "Decomposition rates, synthesis, and spectral properties of a series of alkyl hyponitrites". J. Org. Chem. 48 (21): 3728–3733. doi:10.1021/jo00169a023.