Copper peroxide is an inorganic compound with the chemical formula . The 1:2 ratio of copper and oxygen would be consistent with copper in its common +2 oxidation state and a peroxide group. has attracted interest from a computational perspective.
Older literature claims that treatment of cold suspended Cu(OH)2 with H2O2 creates a brown hydrate of "copper dioxide," which rapidly decomposes in the presence of water to form ill-defined green and yellow salts above 0 °C.Osborne, T. B. (1886). The higher oxides of copper. American Journal of Science, s3-32(191), 333–342. https://doi.org/10.2475/ajs.s3-32.191.333
History Species claimed to be "copper peroxide" have been claimed, e.g., by the reaction of cold solutions of Schweizer's reagent—a source of copper(II)—and hydrogen peroxide. The Schweizer's reagent used must not contain excess ammonia.
It was once claimed to result from the very slow reaction of finely divided cupric oxide with cold hydrogen peroxide.
It has been claimed that brown "copper dioxide" synthesized from Cu(OH)2 can be dried above 100 °C without decomposition if the product is thoroughly rid of moisture via alcohol washings. The resulting product is claimed to be a copper peroxide hydrate.
Several well-characterized molecular copper peroxide complexes have been reported, but these species always feature supporting organic ligands.
Structure Several substances claimed to be inorganic copper(II) peroxides have been reported, with empirical formulae:
, a dark brown solid prepared by the reaction of freshly-made (blue) with moderate-concentration solutions of between −20 °C and 20 °C. An alternative route is the reaction of an ethanol–water solution of with , followed by ethanolic , at −40 to −50 °C. Possible structures include (mixed hydroxide-hydroperoxide) and (hydrate). Electron spin resonance measurements indicate it does not contain . An early publication claims it turns olive-green with age, as well as upon reaction with excess peroxide. , prepared by the reaction of freshly-made with concentrated solutions of hydrogen peroxide between −36 °C and 20 °C. A possible structure is the perhydrate . , an olive-green solid claimed to be obtainable at −79 °C.
Computational analysis suggests that gaseous adopts an end-on configuration consistent with , copper(I) superoxide.
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