Editing Copper(II) nitrate

{{Distinguish|Copper(I) nitrate}}
{{chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 476996432
| Name           = Copper(II) nitrate
| ImageFile1     = Copper(II)-nitrate-trihydrate-sample.jpg
| ImageFileL2    = Anhydrous-copper(II)-nitrate-unit-cell-3D-bs-17.png
| ImageFileR2    = Beta-copper(II)-nitrate-unit-cell-3D-bs-17.png
| ImageCaptionL2 = alpha polymorph<ref name="Wallwork&Addison" />
| ImageCaptionR2 = beta polymorph<ref name="Troyanov" />
| IUPACName      = Copper(II) nitrate
| OtherNames     = Cupric nitrate
| Section1       = {{Chembox Identifiers
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 17582
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = 9TC879S2ZV
|UNII1_Ref = {{fdacite|correct|FDA}}
|UNII1 = 066PG1506T
|UNII1_Comment = (trihydrate)
|UNII2_Ref = {{fdacite|correct|FDA}}
|UNII2 = 0HP2H86BS6
|UNII2_Comment = (hexahydrate)
|InChI = 1/Cu.2NO3/c;2*2-1(3)4/q+2;2*-1
|SMILES = [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O
|InChIKey = XTVVROIMIGLXTD-UHFFFAOYAG
|PubChem = 18616
|PubChem1 =  9837674
|PubChem1_Comment = (trihydrate)
|PubChem2 = 9839123
|PubChem2_Comment = (hexahydrate)
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/Cu.2NO3/c;2*2-1(3)4/q+2;2*-1
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = XTVVROIMIGLXTD-UHFFFAOYSA-N
|CASNo = 3251-23-8
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo1_Ref = {{cascite|correct|CAS}}
|CASNo1 = 10031-43-3
|CASNo1_Comment = (trihydrate)
|CASNo2_Ref = {{cascite|correct|CAS}}
|CASNo2 = 13478-38-1
|CASNo2_Comment = (hexahydrate)
|CASNo3_Ref = {{cascite|changed|??}}
|CASNo3 = 19004-19-4 
|CASNo3_Comment = (hemipentahydrate)
|RTECS = GL7875000
|ChEBI_Ref = {{ebicite|changed|EBI}} 
|ChEBI = 78036
}}
| Section2       = {{Chembox Properties
|Formula = {{chem2|Cu(NO3)2}}
|MolarMass = 187.5558 g/mol (anhydrous) <br> 241.60 g/mol (trihydrate) <br> 232.591 g/mol (hemipentahydrate)
|Appearance = blue-green crystals (anhydrous)<br>blue crystals (hydrate)
|Density = 3.05 g/cm<sup>3</sup> (anhydrous) <br> 2.32 g/cm<sup>3</sup> (trihydrate) <br> 2.07 g/cm<sup>3</sup> (hexahydrate)
|Solubility = ''trihydrate:<ref name="Perrys' Chem Eng Handbook, 7th Ed">Perrys' Chem Eng Handbook, 7th Ed</ref>'' <br> 381 g/100 mL (40 °C) <br> 666 g/100 mL (80 °C)<br> ''hexahydrate:<ref name="Perrys' Chem Eng Handbook, 7th Ed"/>'' <br> 243.7 g/100 mL (80 °C) 
|SolubleOther = hydrates very soluble in [[ethanol]], [[ammonia]], [[water]]; insoluble in [[ethyl acetate]]
|MeltingPtC = 114
|MeltingPt_notes = (anhydrous, decomposes) <br> 114.5 °C (trihydrate) <br> 26.4 °C (hexahydrate, decomposes)
|BoilingPtC = 170
|BoilingPt_notes = (trihydrate, decomposes)
|MagSus = +1570.0·10<sup>−6</sup> cm<sup>3</sup>/mol (~3H<sub>2</sub>O)
}}
| Section3       = {{Chembox Structure
| CrystalStruct = orthorhombic (anhydrous) <br> rhombohedral (hydrates)
}}
| Section7       = {{Chembox Hazards
|ExternalSDS = [http://hazard.com/msds/mf/baker/baker/files/c5874.htm Cu(NO<sub>3</sub>)<sub>2</sub>·3H<sub>2</sub>O]
|MainHazards = Irritant, Oxidizer
|NFPA-H =1
|NFPA-F =0
|NFPA-R =3
|NFPA-S = OX
|PEL = TWA 1 mg/m<sup>3</sup> (as Cu)<ref name=PGCH>{{PGCH|0150}}</ref>
|REL = TWA 1 mg/m<sup>3</sup> (as Cu)<ref name=PGCH/>
|IDLH =  TWA 100 mg/m<sup>3</sup> (as Cu)<ref name=PGCH/>
}}
| Section8       = {{Chembox Related
|OtherAnions = [[Copper(II) sulfate]]<br/>[[Copper(II) chloride]]
|OtherCations = [[Silver nitrate]]<br/>[[Gold(III) nitrate]]
}}
}}

'''Copper(II) nitrate''' describes any member of the family of [[inorganic compound]]s with the formula [[Copper|Cu]]([[Nitrate|NO<sub>3</sub>]])<sub>2</sub>(H<sub>2</sub>O)<sub>x</sub>. The hydrates are [[hygroscopic]] blue [[solid]]s.  [[Anhydrous]] copper nitrate forms blue-green crystals and [[Sublimation (phase transition)|sublimes]] in a vacuum at 150-200 °C.<ref>{{cite book |last=Pass and Sutcliffe |title=Practical Inorganic Chemistry |year=1968 |publisher=Chapman and Hall |location=London}}</ref><ref name="G&E">{{Greenwood&Earnshaw2nd|page=1190}}</ref> Common hydrates are the hemipentahydrate and trihydrate.

==Synthesis and reactions==
===Hydrated copper(II) nitrate ===
Hydrated copper nitrate is prepared by treating copper metal or its oxide with [[nitric acid]]:<ref name=Ullmann/>

:{{chem2|Cu + 4 HNO3 -> Cu(NO3)2 + 2 H2O + 2 NO2}}
The same salts can be prepared treating copper metal with an [[aqueous solution]] of [[silver nitrate]].  That reaction illustrates the ability of copper metal to reduce silver ions.

In aqueous solution, the hydrates exist as the [[aqua complex]] {{chem2|[Cu(H2O)6](2+)}}. Such complexes are highly labile and subject to rapid ligand exchange due to the d<sup>9</sup> electronic configuration of copper(II).

Attempted dehydration of any of the hydrated copper(II) nitrates by heating affords the oxides, not {{chem2|Cu(NO3)2}}.<ref name="G&E" /> At 80&nbsp;°C the hydrates convert to "basic copper nitrate", {{chem2|Cu2(NO3)(OH)3}}, which converts to {{chem2|CuO}} at 180 °C.<ref name=Ullmann/> Exploiting this reactivity, copper nitrate can be used to generate [[nitric acid]] by heating it until decomposition and passing the fumes directly into water. This method is similar to the last step in the [[Ostwald process]]. The equations are as follows:

:{{chem2|2 Cu(NO3)2 -> 2 CuO + 4 NO2 + O2}}
:{{chem2|3 NO2 + H2O -> 2 HNO3 + NO}}

Treatment of copper(II) nitrate solutions with [[triphenylphosphine]], [[triphenylarsine]], and [[triphenylstibine]] gives the corresponding copper(I) complexes {{chem2|[Cu(EPh3)3]NO3}} (E = P, As, Sb; Ph = {{chem2|C6H5}}).  The group V ligand is oxidized to the oxide.<ref>{{cite book |last1=Gysling |first1=Henry J. |title=Inorganic Syntheses |series=Inorganic Syntheses |year=1979 |volume=19 |pages=92–97 |chapter=Coordination Complexes of Copper(I) Nitrate |doi=10.1002/9780470132500.ch19 |isbn=9780470132500}}</ref>

===Anhydrous copper(II) nitrate ===
Anhydrous {{chem2|Cu(NO3)2}} is one of the few anhydrous transition metal nitrates.<ref>{{cite journal |doi=10.1039/qr9712500289 |title=Structural Aspects of Co-ordinated Nitrate Groups |year=1971 |last1=Addison |first1=C. C. |last2=Logan |first2=N. |last3=Wallwork |first3=S. C. |last4=Garner |first4=C. D. |journal=Quarterly Reviews, Chemical Society |volume=25 |issue=2 |page=289}}</ref> It cannot be prepared by reactions containing or producing water. Instead, anhydrous {{chem2|Cu(NO3)2}} forms when copper metal is treated with [[dinitrogen tetroxide]]:<ref name="G&E" />

:{{chem2|Cu + 2 N2O4 -> Cu(NO3)2 + 2 NO}}

==Structure==
===Anhydrous copper(II) nitrate===
[[File:Copper(II)-nitrate-monomer-2D-dimensions.png|thumb|left|Structure of anhydrous copper(II) nitrate in the gas phase.<ref name="G&E" />]]

Two [[polymorphism (materials science)|polymorph]]s of anhydrous copper(II) nitrate, α and β, are known.<ref name="G&E" /> Both polymorphs are three-dimensional [[coordination polymer]] networks with infinite chains of copper(II) centers and nitrate groups. The α form has only one Cu environment, with [4+1] coordination,<ref name="Wallwork&Addison">{{cite journal |last1=Wallwork |first1=S. C. |last2=Addison |first2=W. E. |year=1965 |title=526. The crystal structures of anhydrous nitrates and their complexes. Part I. The α form of copper(II) nitrate |journal=J. Chem. Soc. |volume=1965 |pages=2925–2933 |doi=10.1039/JR9650002925}}</ref> but the β form has two different copper centers, one with [4+1] and one that is square planar.<ref name=Troyanov>{{cite journal |last1=Troyanov |first1=S. I. |last2=Morozov |first2=I. V. |last3=Znamenkov |first3=K. O. |last4=Yu |last5=Korenev |first5=M. |year=1995 |title=Synthesis and X-Ray Structure of New Copper(II) Nitrates: Cu(NO<sub>3</sub>)<sub>2</sub>·H<sub>2</sub>O and β-modification of Cu(NO<sub>3</sub>)<sub>2</sub> |journal=Z. Anorg. Allg. Chem. |volume=621 |issue=7 |pages=1261–1265 |doi=10.1002/zaac.19956210727}}</ref>

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.<ref>{{cite journal |last1=Duffin |first1=B. |last2=Wallwork |first2=S. C. |year=1966 |title=The crystal structure of anhydrous nitrates and their complexes. II. The 1:1 copper(II) nitrate-nitromethane complex |journal=[[Acta Crystallographica]] |volume=20 |issue=2 |pages=210–213 |doi=10.1107/S0365110X66000434 |doi-access=}}</ref>

Heating solid anhydrous copper(II) nitrate under a vacuum to 150-200 °C leads to sublimation and "[[Cracking (chemistry)|cracking]]" to give a vapour of monomeric copper(II) nitrate molecules.<ref name="G&E" /><ref>{{ cite journal | title = 628. The vapour pressure of anhydrous copper nitrate, and its molecular weight in the vapour state | first1 = C. C. | last1 = Addison | first2 = B. J. | last2 = Hathaway | journal = [[Journal of the Chemical Society|J. Chem. Soc.]] | year = 1958 | pages = 3099-3106  | doi = 10.1039/JR9580003099 }}</ref> In the vapour phase, the molecule features two bidentate nitrate ligands.<ref>{{cite journal |last1=LaVilla |first1=R. E. |last2=Bauer |first2=S. H. |year=1963 |title=The Structure of Gaseous Copper(II) Nitrate as Determined by Electron Diffraction |journal=J. Am. Chem. Soc. |volume=85 |issue=22 |pages=3597–3600 |doi=10.1021/ja00905a015}}</ref> 

===Hydrated copper(II) nitrate===
Five [[water of hydration|hydrates]] have been reported: the monohydrate ({{chem2|Cu(NO3)2*2H2O}}),<ref name=Troyanov/> the sesquihydrate ({{chem2|Cu(NO3)2*1.5H2O}}),<ref>{{cite journal |last1=Dornberger-Schiff |first1=K. |last2=Leciejewicz |first2=J. |year=1958 |title=Zur Struktur des Kupfernitrates Cu(NO<sub>3</sub>)<sub>2</sub><sup>.</sup>1.5H<sub>2</sub>O |journal=[[Acta Crystallogr]] |volume=11 |issue=11 |pages=825–826 |doi=10.1107/S0365110X58002322 |doi-access=}}</ref> the hemipentahydrate ({{chem2|Cu(NO3)2*2.5H2O}}),<ref>{{cite journal |last1=Morosin |first1=B. |year=1970 |title=The crystal structure of Cu(NO<sub>3</sub>)<sub>2</sub>.2.5H<sub>2</sub>O |journal=[[Acta Crystallographica Section B]] |volume=26 |issue=9 |pages=1203–1208 |doi=10.1107/S0567740870003898}}</ref> a trihydrate ({{chem2|Cu(NO3)2*3H2O}}),<ref>J. Garaj, ''Sbornik Prac. Chem.-Technol. Fak. Svst., Cskosl.'' 1966, pp. 35–39.</ref> and a hexahydrate ({{chem2|[Cu(OH2)6](NO3)2}}.<ref>{{cite journal |last1=Zibaseresht |first1=R. |last2=Hartshorn |first2=R. M. |year=2006 |title=Hexaaquacopper(II) dinitrate: absence of Jahn-Teller distortion |journal=[[Acta Crystallographica Section E]] |volume=62 |pages=i19–i22 |doi=10.1107/S1600536805041851}}</ref> The crystal structure of the hexahydrate appeared to show six almost equal Cu–O 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 Cu-O bonds but it is probably due to nickel being misidentified as copper in the refinement.

==Applications==
Copper(II) nitrate finds a variety of applications, the main one being its conversion to [[copper(II) oxide]], which is used as [[catalyst]] for a variety of processes in [[organic chemistry]].  Its solutions are used in textiles and polishing agents for other metals. Copper nitrates are found in some [[pyrotechnic]]s.<ref name=Ullmann>H.Wayne Richardson "Copper Compounds" Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim.  {{doi|10.1002/14356007.a07_567}}.</ref>  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]].<ref>{{cite journal |author=Menke J.B. |title=Nitration with nitrates |journal=Recueil des Travaux Chimiques des Pays-Bas |volume=44 |year=1925 |pages=141 |doi=10.1002/recl.19250440209}}</ref>
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 [[thiol]]s to [[disulfide]]s.  Claycop is also used to convert dithioacetals to carbonyls.<ref>Balogh, M. "Copper(II) Nitrate–K10 Bentonite Clay"  in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. {{doi|10.1002/047084289X}}.</ref>  A related reagent based on [[montmorillonite]] has proven useful for the [[nitration]] of aromatic compounds.<ref>{{cite journal |doi=10.1002/anie.199005351 |volume=29 |issue=5 |title=Clays Direct Aromatic Nitration |year=1990 |journal=Angewandte Chemie International Edition in English |pages=535–536 |last1=Collet |first1=Christine}}</ref>

=== Electrowinning ===
Copper(II) nitrate may also be used for copper [[electrowinning]] on small scale with a ammonia (NH<sub>3</sub>) as a byproduct.<ref>{{Cite journal |last=Oishi |first=Tetsuo |last2=Koyama |first2=Kazuya |last3=Konishi |first3=Hirokazu |last4=Tanaka |first4=Mikiya |last5=Lee |first5=Jae-Chun |date=November 2007 |title=Influence of ammonium salt on electrowinning of copper from ammoniacal alkaline solutions |url=https://linkinghub.elsevier.com/retrieve/pii/S001346860700802X |journal=Electrochimica Acta |language=en |volume=53 |issue=1 |pages=127–132 |doi=10.1016/j.electacta.2007.06.024|url-access=subscription }}</ref>

==Naturally occurring copper nitrates==
No mineral of the ideal {{chem2|Cu(NO3)}} formula, or the hydrates, are known. Likasite, {{chem2|Cu3(NO3)(OH)5*2H2O}} and buttgenbachite, {{chem2|Cu19(NO3)2(OH)32Cl4*2H2O}} are related minerals.<ref name=min2399>{{Cite web |url=https://www.mindat.org/min2399.html |title=Likasite |website=www.mindat.org}}</ref><ref name=min811/>

{{anchor|gerhardtite}} Natural basic copper nitrates include the rare minerals [[gerhardtite]] and rouaite, both being polymorphs of {{chem2|Cu2(NO3)(OH)3}}.<ref>{{Cite web |url=https://www.mindat.org/min-1680.html |title=Gerhardtite |website=www.mindat.org}}</ref><ref>{{Cite web |url=https://www.mindat.org/min-10588.html |title=Rouaite |website=www.mindat.org}}</ref><ref name=IMA>{{Cite web |url=https://www.ima-mineralogy.org/Minlist.htm |title=List of Minerals |date=21 March 2011 |website=www.ima-mineralogy.org |author=International Mineralogical Association}}</ref> A much more complex, basic, hydrated and chloride-bearing natural salt is buttgenbachite.<ref name=min811>{{Cite web |url=https://www.mindat.org/min811.html |title=Buttgenbachite |website=www.mindat.org}}</ref><ref name=IMA/>

==References==
{{Reflist}}

==External links==
{{Commons category|Copper(II) nitrate}}

*[https://web.archive.org/web/20130530211504/http://www.npi.gov.au/substances/copper/index.html National Pollutant Inventory – Copper and compounds fact sheet]
*[https://web.archive.org/web/20170905225218/https://www.cdc.gov/niosh/ipcsneng/neng0240.html ICSC Copper and compounds fact sheet]

{{Copper compounds}}
{{nitrates}}

[[Category:Copper(II) compounds]]
[[Category:Nitrates]]
[[Category:Pyrotechnic oxidizers]]
[[Category:Pyrotechnic colorants]]
[[Category:Oxidizing agents]]