Angeli's salt

Angeli's salt
Identifiers
3D model (JSmol)
Properties
N2Na2O3
Molar mass 121.99 g·mol−1
Appearance white solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Angeli's salt, sodium trioxodinitrate, is the inorganic compound with the formula Na2[N2O3]. It contains nitrogen in an unusual reduced state. It is a colorless, water-soluble solid, a salt. In research, this salt is used as a source of the metastable nitroxyl (HNO), which is a signalling molecule in nature.[1] It is also known by the name sodium trioxodinitrate(II) monohydrate.

As first reported by Angeli in 1896, the salt is prepared by combining hydroxylamine and an organic nitrate, as a source of NO2+:[2][3]

NH2OH + RONO2 + 2 NaOR' → ROH + 2 R'OH + Na2N2O3

The structure of the hydrate has been confirmed by X-ray crystallography. The anion is planar. Starting from the ONN end, the bond distances are 1.35 (N-O), 1.26 (N-N), 1.31 (N-O), 1.32 Å (N-O). Negative charge is on the oxygen atoms at opposite ends of the molecule. The angles are single oxygen to nitrogen-nitrogen bond 112.9°, nitrogen-nitrogen bond to trans oxygen 118.4°, nitrogen-nitrogen bond to cis oxygen 122.5°. This means that the nitrogen-nitrogen bond is a double bond, and that the cis oxygen is slightly repelled by the single oxygen.[4]

References

  1. ↑ Nakagawa, H. (2013). "Controlled release of HNO from chemical donors for biological applications". J. Inorg. Biochem. 118: 187–190. doi:10.1016/j.jinorgbio.2012.10.004.
  2. ↑ A. Angeli (1896). "Sopra la nitroidrossilammina". Gazz. Chim. Ital. 26: 17-28.
  3. ↑ Hughes, Martin N.; Cammack, Richard (1999). "Synthesis, chemistry, and Applications of Nitroxyl Ion Releasers Sodium Trioxodinitrate or Angeli's Salt and Piloty's Acid". Methods in Enzymology (Nitric Oxide, Part C: Biological and Antioxidant Activities). 301: 279–287.
  4. ↑ Hope, Hakon; Sequeira, Michael R. (February 1973). "Angeli's salt. Crystal structure of sodium trioxodinitrate(II) monohydrate, Na2N2O3.H2O". Inorganic Chemistry. 12: 286–288. doi:10.1021/ic50120a008.
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