Silver oxide
Template:Chembox new Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.
Preparation
Silver oxide is commercially available. It can be easily prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide.[1] Noteworthy is the fact that this reaction does not afford the hydroxide.
Properties
Like most binary oxides, Ag2O is a three-dimensional polymer with covalent metal-oxygen bonding. It is therefore expected that Ag2O is insoluble in all solvents,[2] except by reaction. It is also slightly soluble in aqueous solution due to the formation of the ion, Ag(OH)2– and possibly related hydrolysis products.[3] It hydrolyzes only slightly in water (1 part in 40,000) and dissolves in ammonium hydroxide solution to give soluble derivatives.
A slurry of Ag2O is readily attacked by acids:
- Ag2O + 2 HX → 2 AgX + H2O
where HX = HF, HCl, HBr, or HI, HO2CCF3. It will also react with solutions of alkali chlorides to precipitate silver chloride, leaving a solution of the corresponding alkali hydroxide.[4][3]
Like many silver compounds, silver oxide is photosensitive. It also decomposes at temperatures above 200 °C.[2]
Applications
Silver oxide is used in a silver-oxide battery. Silver oxide reacts easily with ligand precursors such as 1,3-disubstituted imidazolium or benzimidazolium salts to generate the corresponding N-heterocyclic carbene complexes. These silver complexes are useful as carbene-transfer agents, easily displacing labile ligands such as cyclooctadiene or acetonitrile. This is a common way of synthesizing transition metal carbene complexes.[5]
References
- ^ This publication gives the preparation of Ag2O and silver trifluoroacetate: "4-Iodoveratrole" Janssen, D. E.; Wilson, C. V. Organic Syntheses, Collected Volume 4, pp. 547 (1963). http://www.orgsyn.org/orgsyn/pdfs/CV4P0547.pdf
- ^ a b Merck Index of Chemicals and Drugs, 9th ed. monograph 8265
- ^ a b Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry (2nd Ed.). New York:Interscience.
{{cite book}}: CS1 maint: multiple names: authors list (link) Advanced Inorganic Chemistry by Cotton and Wilkinson, 2nd ed. p1042 - ^ Cite error: The named reference
paulingwas invoked but never defined (see the help page). - ^ Wang, H. M. J.; Lin, I. J. B. "Facile Synthesis of Silver(I)-Carbene Complexes. Useful Carbene Transfer Agents" Organometallics 1998, 17, 972-975. doi:10.1021/om9709704
See also
- silver(II) oxide, AgO