|Solvent1 = ethanol
|Solubility1 = hydrates very soluble
|Solvent2 = ammonia
|Solubility2 = hydrates very soluble
|MeltingPt_notes =
|MeltingPt_ref =
|BoilingPtC = 170
|BoilingPt_notes = (trihydrate, decomposes)
|BoilingPt_ref =
|MagSus = (trihydrate)
| Section3 =
| Section7 =
| Section8 =
Copper(II) nitrate describes any member of the family of inorganic compounds with the formula . The hydrates are hygroscopic blue solids. Anhydrous copper nitrate forms blue-green crystals and sublimes in a vacuum at . Common hydrates are the hemipentahydrate and trihydrate.
Occurrence
No mineral of the ideal formula, or the hydrates, are known.
, and , are related minerals. Natural basic copper nitrates include the rare minerals gerhardtite and , both being polymorphs of . A much more complex, basic, hydrated and chloride-bearing natural salt is buttgenbachite.
Structure
Anhydrous copper(II) nitrate
[[File:Copper(II)-nitrate-monomer-2D-dimensions.png|thumb|class=skin-invert-image|left|Structure of anhydrous copper(II) nitrate in the gas phase.
The nitromethane solvate also features "[4+1] coordination", with four short Cu-O bonds of approximately 200 pm and one longer bond at 240 pm.
Heating solid anhydrous copper(II) nitrate under a vacuum to leads to sublimation and cracking to give a vapour of monomeric copper(II) nitrate molecules. In the vapour phase, the molecule features two bidentate nitrate ligands.
Hydrated copper(II) nitrate
Five hydrates have been reported: the monohydrate (), the sesquihydrate (), the hemipentahydrate (), a trihydrate (), and a hexahydrate (.
The crystal structure of the hexahydrate appeared to show six almost equal distances, not revealing the usual effect of a Jahn-Teller distortion that is otherwise characteristic of octahedral Cu(II) complexes. This non-effect was attributed to the strong hydrogen bonding that limits the elasticity of the bonds but it is probably due to nickel being misidentified as copper in the refinement.
Synthesis and reactions
Hydrated copper(II) nitrate
Hydrated copper nitrate is prepared by treating copper metal or its oxide with nitric acid:
Anhydrous copper(II) nitrate
Anhydrous is one of the few anhydrous transition metal nitrates. It cannot be prepared by reactions containing or producing water. Instead, anhydrous forms when copper metal is treated with dinitrogen tetroxide: It is often used in school laboratories to demonstrate chemical voltaic cell reactions. It is a component in some ceramic glazes and metal patinas.
Organic synthesis
Copper nitrate, in combination with acetic anhydride, is an effective reagent for nitration of aromatic compounds, known as the Menke nitration.
Hydrated copper nitrate adsorbed onto clay affords a reagent called "Claycop". The resulting blue-colored clay is used as a slurry, for example for the oxidation of thiols to disulfides. Claycop is also used to convert dithioacetals to carbonyls. A related reagent based on montmorillonite has proven useful for the nitration of aromatic compounds.
Electrowinning
Copper(II) nitrate may also be used for copper electrowinning on small scale with a ammonia () as a byproduct.