Silver hyponitrite explained

Silver hyponitrite is an ionic compound with formula Ag₂N₂O₂ or ₂[ON=NO]²⁻, containing monovalent silver cations and hyponitrite anions. It is a bright yellow solid practically insoluble in water and most organic solvents, including DMF and DMSO.^{[1] [2] [3]}

Preparation

The compound was described in 1848.^[4]

The salt can be precipitated from a solution of sodium hyponitrite in water by the addition of silver nitrate:^[2]

+ 2 → + 2 Excess silver nitrate yields a brown or black precipitate.^{[1] [2]}

Silver hyponitrite can also be prepared by reacting silver nitrate with sodium amalgam.

Properties and reactions

Silver hyponitrite is sparingly soluble in concentrated alkali hyponitrite solutions, but quite soluble in aqueous ammonia due to the formation of the complex cation [({{chem|N|H|3}})₂Ag]⁺.^[5] The compound is slowly decomposed by light.^[6]

The anhydrous compound decomposes in vacuum at 158 °C. The primary decomposition products are silver(I) oxide and nitrous oxide . However, these then react to form a variable mixture of nitrogen, metallic silver, and various oxides of the two elements and silver salts.^[1]

Hyponitrous acid

Reaction of silver hyponitrite with anhydrous hydrogen chloride in ether is the standard way to prepare hyponitrous acid:

+ 2 HCl → + 2 AgClSpectroscopic data indicate a trans configuration for the resulting acid.^[7]

Alkyl halides

Silver hyponitrite reacts with alkyl halides, to form alkyl hyponitrites. For example, reaction with methyl bromide yields the spontaneously explosive dimethyl hyponitrite:^[2]

2 + → -O-N=N-O- + 2 AgBrOther alkyl hyponitrites reported in the literature include those of ethyl,^[8] benzyl,^{[9] [10] [11]} and tert-butyl.^{[12] [13] [14]}

Notes and References

1. Trambaklal Mohanlal Oza, Rajnikant Hariprasad Thaker (1955), "The Thermal Decomposition of Silver Hyponitrite". Journal of the American Chemical society, volume 77, issue 19, pages 4976–4980.
2. G. David Mendenhall (1974), "Convenient synthesis of silver hyponitrite". Journal of the American Chemical society, volume 96, issue 15, page 5000.
3. Book: Egon . Wiberg . Arnold Frederick . Holleman . 2001 . Inorganic Chemistry . Elsevier . 0-12-352651-5.
4. (1848), "On the formation of hyponitrite of silver". Philosophical Magazine Series 3, XIII. Intelligence and miscellaneous articles, volume 33 (1848), issue 219, page 75.
5. C.N. Polydoropoulos, Th. Yannakopoulos (1961), "Silver hyponitrite: Solubility product and complexes in aqueous ammonia". Journal of Inorganic and Nuclear Chemistry, volume 19, issues 1–2, pages 107–114.
6. Masatsugu Sekiguchi, Michio Kobayashi, Hiroshi Minato (1974), "Reactions between Acyl Halides and Silver Hyponitrite". Bulletin of the Chemical Society of Japan, volume 45, issue 9, pages 2932-2934.
7. Book: Inorganic Chemistry . limited . 3rd . Chapter 15: The group 15 elements . Catherine E. Housecroft . Alan G. Sharpe. Pearson . 2008 . 978-0-13-175553-6 . 468.
8. J. R. Partington and C. C. Shah (1932), J. Chem. Soc., page 2589.
9. Ho . S. K. . de Sousa . J. B. . 347. Alkoxy-radicals. Part I. The kinetics of thermal decomposition of dibenzyl hyponitrite in solution . Journal of the Chemical Society (Resumed) . 1961 . 1788 . 10.1039/JR9610001788.
10. J. B. Sousa and S. K. Ho (1960), Nature, volume 186, page 776.
11. Ray . N. H. . 794. The rates of decomposition of free-radical polymerisation-catalysts: measurements of short half-lives by a thermal method . Journal of the Chemical Society (Resumed) . 1 January 1960 . 4023–4028 . 10.1039/JR9600004023.
12. H. Kiefer and T. G. Traylor (1966), Tetrahedron Lett., page 6163.
13. Huang . R. L. . Lee . Tong-Wai . Ong . S. H. . Reactions of the α-methoxybenzyl radical in carbon tetrachloride and in other solvents. Carbon tetrachloride as a chlorinating agent . Journal of the Chemical Society C: Organic . 1 January 1969 . 1 . 40–44 . 10.1039/J39690000040.
14. R. C. Neuman and R. J. Bussey (1970), J. Am. Chem. Soc., volume 92, page 2440.