Hyponitrite

In chemistry, hyponitrite may refer to the anion N
2O2−
2 ([ON=NO]2−), or to any ionic compound that contains it. In organic chemistry, it may also refer to the group −O−N=N−O−, or any organic compound with the generic formula R1−O−N=N−O−R2, where R1 and R2 are organic groups.[1] Such compounds can be viewed as salts and esters of respectively hyponitrous acid H
2N
2O
2 or HON=NOH.

Bis(hyponitrite)
Names
Preferred IUPAC name
Hyponitrite
Systematic IUPAC name
Diazenebis(olate)
Other names
Hyponitrite(2–)
Identifiers
3D model (JSmol)
3DMet
ChEBI
ChemSpider
130273
KEGG
Properties
N
2O2−
2
Molar mass 60.012 g·mol−1
Conjugate acid Hyponitrous acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

An acid hyponitrite is an ionic compound with the anion HN
2O−
2 ([HON=NO]−).

Hyponitrite ion

Hyponitrite exhibits cis–trans isomerism.[2]

The trans (E) form is generally found in hyponitrite salts such as sodium hyponitrite (Na
2N
2O
2) and silver(I) hyponitrite (Ag
2N
2O
2).

The cis (Z) form of sodium hyponitrite can be obtained too, and it is more reactive than the trans form.[2] The cis hyponitrite anion is nearly planar and almost symmetric, with lengths of about 140 pm for N−O bond and 120 pm for the N−N bond, and O−N−N angles of about 119°.[3]

Reactions

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.[4]

Hyponitrite can act as a reducing agent for example reducing iodine:[4]

N
2O2−
2 + 3 I
2 + 3 H
2O → NO−
3 + NO−
2 + 6 HI

Hyponitrite esters

Organic trans-hyponitrites R1−O−N=N−O−R2 can be obtained by reacting trans silver(I) hyponitrite Ag
2N
2O
2 with various alkyl halides. For example, reaction with t-butyl chloride yields trans di-tert-butyl hyponitrite.[5][6][7][8]

Other alkyl radicals reported in the literature include ethyl,[9] and benzyl.[10][11][12] These compounds can be a source of alkoxyl radicals.[13]

See also

Other nitrogen oxoanions include

References
  1. M. N. Hughes (1968), "Hyponitrites". Quarterly Reviews of the Chemical Society, volume 22, issue 1, pages 1–13. doi:10.1039/QR9682200001.
  2. Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
  3. Claus Feldmann, Martin Jansen (1996), "cis-Sodium Hyponitrite – A New Preparative Route and a Crystal Structure Analysis". Angewandte Chemie International Edition in English, volume 35, issue 15, pages 1728–1730. doi:10.1002/anie.199617281.
  4. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  5. 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.
  6. H. Kiefer and T. G. Traylor (1966), Tetrahedron Lett., page 6163.
  7. R. L. Huang, T. W. Lee, and S. H. Ong (1969), J. Chem. Soc. C, page 40.
  8. R. C. Neuman and R. J. Bussey (1970), J. Am. Chem. Soc., volume 92, page 2440.
  9. J. R. Partington and C. C. Shah (1932), J. Chem. Soc., page 2589.
  10. J. B. Sousa and S. K. Ho (1961), J. Chem. Soc., page 1788.
  11. J. B. Sousa and S. K. Ho (1960), Nature, volume 186, page 776.
  12. N. H. Ray (1960), J. Chem. Soc., page 4023.
  13. 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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