View source for Copper monosulfide

{{chembox
|Watchedfields = changed
|verifiedrevid = 440734948
|ImageFile = Sulfid měďnatý.PNG
|IUPACName = Copper sulfide
|OtherNames = [[Covellite]]<br/>Copper(II) sulfide<br/>Cupric sulfide
|Section1={{Chembox Identifiers
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 14145
|InChI = 1/Cu.S/rCuS/c1-2
|SMILES = [Cu]=S
|InChIKey = BWFPGXWASODCHM-BLKBWTQCAT
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/Cu.S
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = BWFPGXWASODCHM-UHFFFAOYSA-N
|CASNo = 1317-40-4
|CASNo_Ref = {{cascite|correct|CAS}}
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = KL4YU612X7
|PubChem = 14831
|RTECS = GL8912000
|EC_number = 215-271-2
}}
|Section2={{Chembox Properties
|Formula = CuS
|MolarMass = 95.611 g/mol
|Appearance = black powder or lumps
|Density = 4.76 g/cm<sup>3</sup>
|MeltingPt= above
|MeltingPtC = 500
|MeltingPt_notes = (decomposes)<ref name = "Blachnik">{{Cite journal | last = Blachnik | first = R. |author2=Müller, A. | year = 2000 | title = The formation of Cu<sub>2</sub>S from the elements I. Copper used in form of powders | journal= Thermochimica Acta | volume = 361 | issue = 1–2 | pages= 31–52 | doi= 10.1016/S0040-6031(00)00545-1 }}</ref>
|Solubility = 0.000033 g/100 ml (18 °C)
|SolubilityProduct = 6 x 10<sup>−37</sup><ref>{{cite journal | title=The new low value for the second dissociation constant for H2S: Its history, its best value, and its impact on the teaching of sulfide equilibria | author=Rollie J. Myers | journal=J. Chem. Educ. | year=1986 | volume=63 | issue=8 | pages=687 |doi=10.1021/ed063p687| bibcode=1986JChEd..63..687M }}</ref>
|SolubleOther = soluble in [[nitric acid|HNO<sub>3</sub>]], [[ammonium hydroxide|NH<sub>4</sub>OH]], [[potassium cyanide|KCN]] <br> insoluble in [[hydrochloric acid|HCl]], [[sulfuric acid|H<sub>2</sub>SO<sub>4</sub>]]
|RefractIndex = 1.45 
|MagSus = −2.0·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
|Section3={{Chembox Structure
|CrystalStruct = hexagonal
}}
|Section4={{Chembox Hazards
|GHSPictograms = {{GHS09}}
|HPhrases = {{H-phrases|413}}
|PPhrases = {{P-phrases|273|501}}
|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/>
}}
|Section5={{Chembox Related
|OtherAnions = [[Copper(II) oxide]]
|OtherCations = [[zinc sulfide]]
}}
}}
'''Copper monosulfide''' <!-- No, it is NOT copper (II), please read the article before changing that --> is a [[chemical compound]] of [[copper]] and [[sulfur]]. It was initially thought to occur in nature as the  dark indigo blue mineral [[covellite]]. However, it was later shown to be rather a cuprous compound, formula {{chem2|Cu3S(S2)}}.<ref name ="Liang & 1993">Liang, W., Whangbo, M.H. (1993) ''Conductivity anisotropy and structural phase transition in Covellite CuS'' Solid State Communications, 85(5), 405-408</ref> CuS is a moderate conductor of electricity.<ref name ="Wells">Wells A.F. (1962) ''Structural Inorganic Chemistry'' 3d edition Oxford University Press</ref> A black colloidal precipitate of CuS is formed when [[hydrogen sulfide]], H<sub>2</sub>S, is bubbled through solutions of Cu(II) salts.<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> It is one of a number of binary compounds of copper and sulfur (see [[copper sulfide]] for an overview of this subject), and has attracted interest because of its potential uses in catalysis<ref>{{cite journal
| last = Kuchmii
| first = S.Y.
| author2=Korzhak A.V.|author3=Raevskaya A.E.|author4=Kryukov A.I.
| year = 2001
| title =Catalysis of the Sodium Sulfide Reduction of Methylviologene by CuS Nanoparticles
| journal = Theoretical and Experimental Chemistry
| volume = 37 
| issue = 1
| pages = 36–41
| publisher = Springer 
| location = New York
| doi = 10.1023/A:1010465823376| s2cid = 91893521
}}</ref> and [[photovoltaics]].<ref>
{{cite journal
| last = Mane
| first = R.S.
| author2=Lokhande C.D.
| date=June 2000
| title =  Chemical deposition method for metal chalcogenide thin films
| journal = Materials Chemistry and Physics    
| volume = 65
| issue = 1| pages = 1–31
| doi = 10.1016/S0254-0584(00)00217-0 }}</ref>

==Manufacturing==
Copper monosulfide can be prepared by passing [[hydrogen sulfide]] gas into a solution of [[copper(II)]] salt.

Alternatively, it can be prepared by melting an excess of [[sulfur]] with [[copper(I) sulfide]] or by precipitation with hydrogen sulfide from a solution of anhydrous [[copper(II) chloride]] in anhydrous [[ethanol]].

The reaction of copper with molten sulfur followed by boiling [[sodium hydroxide]] and the reaction of [[sodium sulfide]] with aqueous [[copper sulfate]] will also produce copper sulfide.

==CuS structure and bonding==
Copper sulfide crystallizes in the hexagonal crystal system, and this is the form of the mineral [[covellite]]. There is also an amorphous high pressure form<ref>{{cite journal
| last =  Peiris
| first = M
|author2=Sweeney, J.S. |author3=Campbell, A.J. |author4=Heinz D. L.
 | year = 1996
| title = Pressure-induced amorphization of covellite, CuS
| journal = J. Chem. Phys.
| volume = 104
| issue = 1| pages = 11–16
| doi = 10.1063/1.470870 |bibcode = 1996JChPh.104...11P }}</ref> which on the basis of the [[Raman spectroscopy|Raman spectrum]] has been described as having a distorted covellite structure. An amorphous room temperature semiconducting form produced by the reaction of a Cu(II) [[ethylenediamine]] complex with [[thiourea]] has been reported, which transforms to the crystalline covellite form at 30 °C.<ref>{{cite journal
| last =  Grijalva
| first = H. |author2=Inoue, M. |author3=Boggavarapu, S. |author4=Calvert, P. 
| year = 1996
| title = Amorphous and crystalline copper sulfides, CuS
| journal = J. Mater. Chem. 
| volume = 6
| issue = 7| pages = 1157–1160
| doi = 10.1039/JM9960601157}}</ref><br />
The crystal structure of covellite has been reported several times,<ref>{{cite journal
| last =  Oftedal
| first =  I.
| title = Die Kristallstruktur des Covellins (CuS)
| year = 1932
| journal = Z. Kristallogr.
| volume = 83
| issue = 1–6
| pages = 9–25
| doi = 10.1524/zkri.1932.83.1.9
| s2cid = 101164006
}}</ref><ref>{{cite journal
| last = Berry 
| first = L. G.
| year = 1954
| title = The crystal structure of covellite CuS and klockmannite CuSe
| journal = American Mineralogist
| volume = 39 
| pages = 504}}</ref><ref name = "Evans">{{cite journal
| last =  Evans
| first = H.T. Jr.
| author2=Konnert J.
| year = 1976
| title = Crystal structure refinement of covellite
| journal = American Mineralogist
| volume = 61
| pages = 996–1000}}</ref> and whilst these studies are in general agreement on assigning the [[space group]] P6<sub>3</sub>/mmc there are small discrepancies in bond lengths and angles between them. The structure was described as "extraordinary" by Wells<ref>Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications {{ISBN|0-19-855370-6}}</ref> and is quite different from [[Copper(II) oxide]], but similar to [[Copper(II) selenide]] (or referred to as Klockmannite). The covellite unit cell contains 6 formula units (12 atoms) in which:
* 4 Cu atoms have tetrahedral coordination (see illustration).
* 2 Cu atoms have trigonal planar coordination (see illustration).
* 2 pairs of S atoms are only 207.1 pm apart<ref name= "Evans"/> indicating the existence of an S-S bond (a disulfide unit).
* the  2 remaining S atoms form trigonal planar triangles around the copper atoms, and are surrounded by five Cu atoms in a pentagonal bipyramid (see illustration).
* The S atoms at each end of a disulfide unit are tetrahedrally coordinated to 3 tetrahedrally coordinated Cu atoms and the other S atom in the disulfide unit (see illustration).
The formulation of copper sulfide as Cu<sup>II</sup>S (i.e. containing no sulfur-sulfur bond) is clearly incompatible with the crystal structure, and also at variance with the observed diamagnetism<ref>[http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elementmagn.pdf Magnetic susceptibility of the elements and inorganic compounds] {{webarchive|url=https://web.archive.org/web/20120112012253/http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elementmagn.pdf |date=2012-01-12 }}</ref> as a Cu(II) compound would have a d<sup>9</sup> configuration and be expected to be paramagnetic.<ref name = "Greenwood"/> <br />
Studies using [[X-ray photoelectron spectroscopy|XPS]]<ref>{{cite journal
| last =  Nakai
| first = I. |author2=Sugitani, Y. |author3=Nagashima, K. |author4=Niwa, Y. 
| year = 1978
| title = X-ray photoelectron spectroscopic study of copper minerals
| journal = Journal of Inorganic and Nuclear Chemistry
| volume = 40
| issue = 5
| pages = 789–791
| doi = 10.1016/0022-1902(78)80152-3}}</ref><ref>{{cite journal
| last =  Folmer
| first = J.C.W.
| author2=Jellinek F.
| year = 1980
| title = The valence of copper in sulfides and selenides: An X-ray photoelectron spectroscopy study
| journal = Journal of the Less Common Metals
| volume = 76
| issue = 1–2
| pages = 789–791
| doi = 10.1016/0022-5088(80)90019-3}}</ref><ref>{{cite journal
| last =  Folmer
| first = J.C.W.
| author2=Jellinek F.|author3=Calis G.H.M
| year = 1988
| title = The electronic structure of pyrites, particularly CuS<sub>2</sub> and Fe<sub>1−''x''</sub>Cu<sub>x</sub>Se<sub><sub><sub>2</sub></sub></sub>: An XPS and Mössbauer study
| journal = Journal of Solid State Chemistry
| volume = 72
| issue = 1
| pages = 137–144
| doi = 10.1016/0022-4596(88)90017-5|bibcode = 1988JSSCh..72..137F }}</ref><ref>{{cite journal
| last =   Goh
| first = S.W.
| author2=Buckley A.N.|author3=Lamb R.N.
| date=February 2006
| title =  Copper(II) sulfide?
| journal = Minerals Engineering
| volume = 19
| issue = 2
| pages = 204–208
| doi = 10.1016/j.mineng.2005.09.003}}</ref> indicate that '''all''' of the copper atoms have an oxidation state of +1. This contradicts a formulation based on the crystal structure and obeying the [[octet rule]] that is found in many textbooks (e.g.<ref name = "Greenwood"/><ref>{{Cotton&Wilkinson6th}}</ref>) describing CuS as containing both Cu<sup>I</sup> and Cu<sup>II</sup> i.e. (Cu<sup>+</sup>)<sub>2</sub>Cu<sup>2+</sup>(S<sub>2</sub>)<sup>2−</sup>S<sup>2−</sup>. An alternative formulation as (Cu<sup>+</sup>)<sub>3</sub>(S<sup>2−</sup>)(S<sub>2</sub>)<sup>−</sup> was proposed and supported by calculations.<ref name = "Liang">{{cite journal
| last =  Liang
| first = W.
| author2=Whangbo M, -H
| date=February 1993
| title = Conductivity anisotropy and structural phase transition in Covellite CuS
| journal = Solid State Communications
| volume = 85
| issue = 5
| pages = 405–408
| doi = 10.1016/0038-1098(93)90689-K|bibcode = 1993SSCom..85..405L }}</ref>
The formulation should not be interpreted as containing radical anion, but rather that there is a delocalized valence "hole".<ref name = "Liang"/><ref>{{cite journal
| last =  Nozaki
| first = H |author2=Shibata, K |author3=Ohhashi,N.
| date=April 1991
| title =Metallic hole conduction in CuS 
| journal =Journal of Solid State Chemistry 
| volume = 91
| issue = 2
| pages = 306–311
| doi = 10.1016/0022-4596(91)90085-V|bibcode = 1991JSSCh..91..306N }}</ref>
[[Electron paramagnetic resonance]] studies on the precipitation of Cu(II) salts indicates that the reduction of Cu(II) to Cu(I) occurs in solution.<ref>{{cite journal
| last = Luther 
| first = GW
| author2=Theberge SM|author3=Rozan TF|author4=Rickard D|author5=Rowlands CC|author6=Oldroyd A.
| date=February 2002
| title = Aqueous copper sulfide clusters as intermediates during copper sulfide formation.
| journal = Environ. Sci. Technol.
| volume = 36
| issue = 3
| pages = 394–402
| doi = 10.1021/es010906k
| pmid = 11871554|bibcode = 2002EnST...36..394L }}</ref>
{| class="wikitable" style="margin:1em auto; text-align:center;"
|
[[Image:Covellite-xtal-CM-3D-balls.png|200px]]
|[[Image:Covellite-Cu1-coordination-3D-balls.png|120px]]||[[Image:Covellite-Cu2-coordination-3D-balls.png|120px]]||[[Image:Covellite-S1-coordination-3D-balls.png|120px]]||[[Image:Covellite-S2-coordination-3D-balls.png|120px]]
|-
|<small>[[ball-and-stick model]] of part of<br>the crystal structure of [[covellite]]</small>||<small>trigonal planar<br>coordination of copper</small>||<small>tetrahedral<br>coordination of copper</small>||<small>trigonal bipyramidal<br>coordination of sulfur</small>||<small>tetrahedral<br>coordination of sulfur-note disulfide unit</small>
|}

==See also==
*[[Copper sulfide]] for an overview of all copper sulfide phases
*[[Copper(I) sulfide]], Cu<sub>2</sub>S
*[[Covellite]]

==References==
{{reflist|30em}}

{{Copper compounds}}
{{Sulfides}}
{{Disulfides}}

[[Category:Sulfides]]
[[Category:Copper(II) compounds]]
[[Category:Disulfides]]