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| Names | |
|---|---|
| IUPAC name Copper sulfide | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.013.884 |
| EC Number |
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| RTECS number |
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| UNII | |
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| Properties | |
| CuS | |
| Molar mass | 95.611 g/mol |
| Appearance | black powder or lumps |
| Density | 4.76 g/cm3 |
| Melting point | above 500 °C (932 °F; 773 K) (decomposes)[2] |
| 3.3×10−5 g/100 ml (18 °C)[citation needed] | |
Solubility product (Ksp) | 5×10−37[1][need quotation to verify] |
| Solubility innitric acid | soluble[citation needed][quantify] |
| Solubility inammonium hydroxide | soluble[citation needed][quantify] |
| −2.0×10−6 cm3/mol | |
Refractive index (nD) | 1.45 |
| Structure | |
| hexagonal | |
| Hazards | |
| GHS labelling: | |
 | |
| H413 | |
| P273,P501 | |
| NIOSH (US health exposure limits):[3] | |
PEL (Permissible) | TWA1 mg/m3 (as Cu) |
REL (Recommended) | TWA1 mg/m3 (as Cu) |
IDLH (Immediate danger) | TWA100 mg/m3 (as Cu) |
| Related compounds | |
Otheranions | Copper(II) oxide |
Othercations | zinc sulfide |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Copper monosulfide is achemical compound ofcopper andsulfur. It was initially thought to occur in nature as the dark indigo blue mineralcovellite. However, it was later shown to be a cuprous compound, formulaCu3S(S2).[4][clarification needed] CuS is a moderate conductor of electricity.[5][page needed] A black colloidal precipitate of CuS is formed whenhydrogen sulfide,H2S, is bubbled through solutions of Cu(II) salts.[6][page needed] It is one of a number of binary compounds of copper and sulfur (seecopper sulfide for an overview of this subject), and has attracted interest because of its potential uses in catalysis[7] andphotovoltaics.[8]
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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 withcopper(I) sulfide or by precipitation with hydrogen sulfide from a solution of anhydrouscopper(II) chloride in anhydrousethanol.
The reaction of copper with molten sulfur followed by boilingsodium hydroxide and the reaction ofsodium sulfide with aqueouscopper sulfate will also produce copper sulfide.
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[9] which on the basis of theRaman 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 withthiourea has been reported, which transforms to the crystalline covellite form at 30 °C (86 °F).[10]
The crystal structure of covellite has been reported several times,[11][12][13] and whilst these studies are in general agreement on assigning thespace group P63/mmc there are small discrepancies in bond lengths and angles between them. The structure was described as "extraordinary" by Wells[14][page needed] and is quite different fromCopper(II) oxide, but similar toCopper(II) selenide (or referred to as Klockmannite). The covellite unit cell contains 6 formula units (12 atoms) in which:
The formulation of copper sulfide asCuIIS (i.e. containing no sulfur-sulfur bond) is clearly incompatible with the crystal structure, and also at variance with the observed diamagnetism[15][page needed] as a Cu(II) compound would have a d9 configuration and be expected to be paramagnetic.[6][page needed]
Studies usingXPS[16][17][18][19] indicate thatall of the copper atoms have an oxidation state of +1. This contradicts a formulation based on the crystal structure and obeying theoctet rule that is found in many textbooks (e.g.[6][page needed][20][page needed]) describing CuS as containing bothCuI andCuII i.e.(Cu+)2Cu2+(S2)2−S2−. An alternative formulation as(Cu+)3(S2−)(S2)− was proposed and supported by calculations. The formulation should not be interpreted as containing radical anion, but rather that there is a delocalized valence "hole".[4][21]Electron paramagnetic resonance studies on the precipitation of Cu(II) salts indicates that the reduction of Cu(II) to Cu(I) occurs in solution.[22]
|  |  |  |  |
| ball-and-stick model of part of the crystal structure ofcovellite | trigonal planar coordination of copper | tetrahedral coordination of copper | trigonal bipyramidal coordination of sulfur | tetrahedral coordination of sulfur-note[clarification needed] disulfide unit |
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