Hyponitrite

Hyponitrite
Names
Preferred IUPAC name
Hyponitrite
Systematic IUPAC name
Oxidoazanylidene
Identifiers
3D model (Jmol) Interactive image
Abbreviations NO((2.)-)
ChEBI CHEBI:29121 N
ChemSpider 2272768 N
PubChem 3001380
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
3D model (Jmol) Interactive image
3DMet B00354
ChEBI CHEBI:18210
ChemSpider 3874228 ()
130273
KEGG C01818
PubChem 6185901 (E)
4686309 ()
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

Main article: 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

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. 1 2 3 4 5 6 7 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. 1 2 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.
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