Copper(II) sulfide
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content
Copper monosulfide
IUPAC name copper monosulfide
Other names covellite, copper(II) sulfide
Identifiers
CAS number 1317-40-4
Properties
Molecular formula CuS
Molar mass 95.61 g/mol
Density 4.6 g/mL
Melting point

above 500°C (decomposes 1)
Solubility in water insoluble
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox references

Copper monosulfide is a chemical compound of copper and sulfur. It occurs in nature as the dark indigo blue mineral covellite. It is a moderate conductor of electricity. 2 A black colloidal precipitate of CuS is formed when hydrogen sulfide, H2S, is bubbled through solutions of Cu(II) salts. 3 It is one of number of binary compounds of copper and sulfur (see copper sulfide). It has attracted interest because of its potential uses in catalysis 4 and photovoltaics5

CuS structure and bonding

Copper monosulfide crystallises in a hexagonal crystal system, and this is the form of the mineral covellite. There is additionally a high pressure amorphous form 6 which on the basis of the Raman spectrum has been described as having a distorted covellite structure. An amorphous room temperature semiconducting form produced by the reaction of Cu(II)ethylenediamine complex with thiourea has been reported which transforms to the crystalline covellite form at 30°C.7
The crystal structure of covellite has been studied a number of times (e.g8 9 10) and while these studies are in general agreement on assigning the space group (P63/mmc) there are small discrepancies in bond lengths and angles between them. The structure was described as extraordinary by A.F Wells.11 and is quite different from copper(II) oxide, but similar to CuSe, 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 10indicating the existence of a S-S bond (a disulfide unit).
  • the 2 remaining S atoms form the 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 monosulfide as CuIIS (i.e containing no sulfur-sulfur bond) is clearly incompatible with the crystal structure, and also at variance with the observed diamagnetism 12 as a Cu(II) compound would have a d9 configuration and be expected to be paramagnetic3
Studies using XPS 13 14 15 16 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. 317) describing CuS as containing both CuI and CuII i.e. (Cu+)2Cu2+(S2)2–S2–. An alternative formulation as (Cu+)3(S2–)(S2)– was proposed and supported by calculations.18 The formulation should not be interpreted as containing radical anion rather that there is a delocalised valence "hole". 1819 EPR studies on the precipitation of Cu(II) salts indicates that the reduction of Cu(II) to Cu(I) occurs in solution. 20
ball-and-stick model of part of
the crystal structure of covellite
trigonal planar
coordination of copper
tetrahedral
coordination of copper
trigonal bipyramidal
coordination of sulfur
tetrahedral
coordination of sulfur-note disulfide unit

See also

References

  1. ^ Blachnik, R.; Müller A. (October 2000). "The formation of Cu2S from the elements I. Copper used in form of powders". Thermochimica Acta 361 (1-2): 31–52. doi:10.1016/S0040-6031(00)00545-1. 
  2. ^ Wells A.F. (1962) Structural Inorganic Chemistry 3d edition Oxford University Press
  3. ^ a b c Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (2nd ed.), Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4 
  4. ^ Kuchmii, S.Y.; Korzhak A.V., Raevskaya A.E.,Kryukov A.I. (2001). "Catalysis of the Sodium Sulfide Reduction of Methylviologene by CuS Nanoparticles". Theoretical and Experimental Chemistry (New York: Springer) 37 (1): 36–41. doi:10.1023/A:1010465823376. 
  5. ^ Mane, R.S.; Lokhande C.D. (June 2000). "Chemical deposition method for metal chalcogenide thin films". Materials Chemistry and Physics 65: 1–31. doi:10.1016/S0254-0584(00)00217-0. 
  6. ^ Peiris, M; Sweeney, J.S.; Campbell, A.J.; Heinz D. L. (1996). "Pressure-induced amorphization of covellite, CuS". J. Chem. Phys. 104: 11 - 16. doi:10.1063/1.470870. 
  7. ^ Grijalva, H.; Inoue, M.; Boggavarapu, S.; Calvert, P. (1996). "Amorphous and crystalline copper sulfides, CuS". J. Mater. Chem. 6: 1157 - 1160. doi:10.1039/JM9960601157. 
  8. ^ Oftedal, I. (1932). . Z. Kristallogr. 83: 9-25. 
  9. ^ Berry, L. G. (1954). "The crystal structure of covellite CuS and klockmannite CuSe". American Mineralogist 39: 504. 
  10. ^ a b Evans, H.T. Jr.; Konnert J. (1976). "Crystal structure refinement of covellite". American Mineralogist 61: 996-1000. 
  11. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  12. ^ [1]
  13. ^ Nakai, I.; Sugitani, Y.; Nagashima, K.; Niwa, Y. (1978). "X-ray photoelectron spectroscopic study of copper minerals". Journal of Inorganic and Nuclear Chemistry 40 (5): 789 - 791. doi:10.1016/0022-1902(78)80152-3. 
  14. ^ Folmer, J.C.W.; Jellinek F. (1980). "The valence of copper in sulphides and selenides: An X-ray photoelectron spectroscopy study". Journal of the Less Common Metals 76 (1-2): 789 - 791. doi:10.1016/0022-5088(80)90019-3. 
  15. ^ Folmer, J.C.W.; Jellinek F., Calis G.H.M (1988). "The electronic structure of pyrites, particularly CuS2 and Fe1−xCuxSe2: An XPS and Mössbauer study". Journal of Solid State Chemistry 72 (1): 137-144. doi:10.1016/0022-4596(88)90017-5. 
  16. ^ Goh, S.W.; Buckley A.N., Lamb R.N. (February 2006). "Copper(II) sulfide?". Minerals Engineering 19 (2): 204 - 208. doi:10.1016/j.mineng.2005.09.003. 
  17. ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5 
  18. ^ a b Liang, W.; Whangbo M, -H (February 1993). "Conductivity anisotropy and structural phase transition in Covellite CuS". Solid State Communications 85 (5): 405 - 408. doi:10.1016/0038-1098(93)90689-K. 
  19. ^ Nozaki, H; Shibata, K; Ohhashi,N. (April 1991). "Metallic hole conduction in CuS". Journal of Solid State Chemistry 91 (2): 306 - 311. doi:10.1016/0022-4596(91)90085-V. 
  20. ^ Luther, GW; Theberge SM, Rozan TF, Rickard D, Rowlands CC, Oldroyd A. (February 2002). "Aqueous copper sulfide clusters as intermediates during copper sulfide formation.". Environ Sci Technol. 36 (3): 394–402. 
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