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hyponitrite

{{Short description|Ion, and compounds containing the ion}}

{{Chembox

| Watchedfields = changed

| ImageFileL1 = Trans-Hyponitrite-ion-3D-balls.png

| ImageFileR1 = Cis-Hyponitrite-ion-3D-balls.png

| ImageCaptionL1 = trans (E) hyponitrite

| ImageCaptionR1 = cis (Z) hyponitrite

| PIN = Hyponitrite

| SystematicName = Diazenebis(olate)

| OtherNames = Hyponitrite(2–)

| IUPACName =

| Section1 = {{Chembox Identifiers

| PubChem = 6185901

| PubChem_Comment = (E)

| PubChem1 = 4686309

| PubChem1_Comment = (unassigned stereochemistry)

| ChemSpiderID = 3874228

| ChemSpiderID_Comment = (?)

| ChEBI = 18210

| SMILES = [O-]/N=N/[O-]

| SMILES_Comment = (E)

| SMILES1 = [O-]\N=N/[O-]

| SMILES1_Comment = (Z)

| InChI=1S/H2N2O2/c3-1-2-4/h(H,1,4)(H,2,3)/p-2

| InChIKey = NFMHSPWHNQRFNR-UHFFFAOYSA-L

| Gmelin = 130273

| 3DMet = B00354}}

| Section2 = {{Chembox Properties

| Formula = {{chem|N|2|O|2|2−}}

| MolarMass = {{chem molar mass|O=2|N=2}}

| ConjugateAcid = Hyponitrous acid}}

| Section3 =

| Section4 =

| Section5 =

| Section6 =

}}

In chemistry, hyponitrite may refer to the anion {{chem|N|2|O|2|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.{{cite journal | doi=10.1039/QR9682200001 | title=Hyponitrites | date=1968 | last1=Hughes | first1=M. N. | journal=Quarterly Reviews, Chemical Society | volume=22 | page=1 }} Such compounds can be viewed as salts and esters of hyponitrous acid.

An acid hyponitrite is an ionic compound with the anion {{chem|H|N|2|O|2|−}} ([HON=NO]−).

Hyponitrite ion

Hyponitrite exhibits cis–trans isomerism.Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier {{ISBN|0-12-352651-5}}

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

The cis (Z) form of sodium hyponitrite can be obtained too, but it is more reactive than the trans form. 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°.{{cite journal | doi=10.1002/anie.199617281 | title=Cis-Sodium Hyponitrite—A New Preparative Route and a Crystal Structure Analysis | date=1996 | last1=Feldmann | first1=Claus | last2=Jansen | first2=Martin | journal=Angewandte Chemie International Edition in English | volume=35 | issue=15 | pages=1728–1730 }}

=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.{{Greenwood&Earnshaw}}

Hyponitrite can reduce elemental iodine to hydroiodic acid:

:{{chem|N|2|O|2|2−}} + 3 {{chem|I|2}} + 3 {{chem|H|2|O}} → {{chem|NO|3|−}} + {{chem|NO|2|−}} + 6 HI

Hyponitrite esters

Organic trans-hyponitrites R1−O−N=N−O−R2 can be obtained by reacting trans silver(I) hyponitrite {{chem|Ag|2|N|2|O|2}} with various alkyl halides. For example, reaction with tert-butyl chloride yields trans di-tert-butyl hyponitrite.{{cite journal | title = Correlation of the Product E/Z Framework Geometry and O/O vs O/N Regioselectivity in the Dialkylation of Hyponitrite |author1=Navamoney Arulsamy |author2=D. Scott Bohle |author3=Jerome A. Imonigie |author4=Elizabeth S. Sagan | journal = J. Am. Chem. Soc. | year = 2000 | volume = 122 | issue = 23 | pages = 5539–5549 | doi = 10.1021/ja994261o}}{{cite journal | last1=Kiefer | first1=Hansruedi | last2=Traylor | first2=T.G. | title=Di-t-butyl hyponitrite. A convenient source of t-butoxy radicals | journal=Tetrahedron Letters | volume=7 | issue=49 | year=1966 | issn=0040-4039 | doi=10.1016/s0040-4039(00)70159-6 | pages=6163–6168}}{{cite journal | last1=Huang | first1=R. L. | last2=Lee | first2=Tong-Wai | last3=Ong | first3=S. H. | title=Reactions of the α-methoxybenzyl radical in carbon tetrachloride and in other solvents. Carbon tetrachloride as a chlorinating agent | journal=J. Chem. Soc. C | issue=1 | year=1969 | issn=0022-4952 | doi=10.1039/j39690000040 | pages=40–44}}{{cite journal | last1=Neuman | first1=Robert C. | last2=Bussey | first2=Robert J. | title=High pressure studies. V. Activation volumes for combination and diffusion of geminate tert-butoxy radicals | journal=Journal of the American Chemical Society | volume=92 | issue=8 | year=1970 | issn=0002-7863 | doi=10.1021/ja00711a039 | pages=2440–2445}}

Other alkyl radicals reported in the literature include ethyl,{{cite journal | last1=Partington | first1=James R. | last2=Shah | first2=Chandulal C. | title=384. Hyponitrites. Part II : metallic salts. Part III : esters | journal=Journal of the Chemical Society | year=1932 | issn=0368-1769 | doi=10.1039/jr9320002589 | page=2589}} and benzyl.{{cite journal | last1=Ho | first1=S. K. | last2=de Sousa | first2=J. B. | title=347. Alkoxy-radicals. Part I. The kinetics of thermal decomposition of dibenzyl hyponitrite in solution | journal=Journal of the Chemical Society | year=1961 | issn=0368-1769 | doi=10.1039/jr9610001788 | page=1788}}{{cite journal | last1=de SOUSA | first1=J. B. | last2=HO | first2=S. K. | title=Disproportionation and Dimerization of the Benzyloxyl Free Radical in Solution | journal=Nature | volume=186 | issue=4727 | year=1960 | issn=0028-0836 | doi=10.1038/186776a0 | pages=776–778| bibcode=1960Natur.186..776D | s2cid=4248607 }}{{cite journal | last=Ray | first=N. H. | title=794. The rates of decomposition of free-radical polymerisation-catalysts: measurements of short half-lives by a thermal method | journal=Journal of the Chemical Society | year=1960 | issn=0368-1769 | doi=10.1039/jr9600004023 | page=4023}} These compounds can be a source of alkoxyl radicals.{{cite journal | title = Decomposition rates, synthesis, and spectral properties of a series of alkyl hyponitrites |author1=Craig A. Ogle |author2=Steven W. Martin |author3=Michael P. Dziobak |author4=Marek W. Urban |author5=G. David Mendenhall | journal = J. Org. Chem. | year = 1983 | volume = 48 | issue = 21 | pages = 3728–3733 | doi = 10.1021/jo00169a023}}

See also

Other nitrogen oxyanions include

References

{{reflist}}

{{Nitrogen compounds}}

Category:Nitrogen oxyanions

Category:Nitrogen–oxygen compounds

Category:Hyponitrites