Potassium tetrachloridocuprate(II)

Potassium tetrachloridocuprate(II)
Names
IUPAC name
Potassium tetrachloridocuprate(II)
Other names
  • Dipotassium cupric chloride
  • Dipotassium tetrachlorocuprate
  • Potassium copper(II) tetrachloride
  • Potassium tetrachlorocuprate
  • Potassium tetrachlorocuprate(II)
  • Mitscherlichite (dihydrate mineral)
Identifiers
3D model (JSmol)
ChemSpider
  • (anhydrous): InChI=1S/4ClH.Cu.2K/h4*1H;;;/q;;;;+2;2*+1/p-4
    Key: FBNNBYUNXDHBOM-UHFFFAOYSA-J
  • (dihydrate): InChI=1S/4ClH.Cu.2K.2H2O/h4*1H;;;;2*1H2/q;;;;+2;2*+1;;/p-4
    Key: QDLOTAGCTPEFOF-UHFFFAOYSA-J
  • (anhydrous): [Cl-].[Cl-].[Cl-].[Cl-].[K+].[K+].[Cu+2]
  • (dihydrate): O.O.[Cl-].[Cl-].[Cl-].[Cl-].[K+].[K+].[Cu+2]
Properties
K2CuCl4 (anhydrous)
K2CuCl4·2H2O (dihydrate)
Molar mass 319.585 g/mol (dihydrate)
Appearance greenish blue crystals (dihydrate)
Density 2.416 g/cm3 at 25 °C (dihydrate)[1]
Structure
(dihydrate:) Tetragonal.Point Group: 4/m 2/m 2/m (probable). Crystals, short prismatic along [001], or pyramidal {011}, minute; in stalactitic growths[2]
Hazards
GHS labelling:
NFPA 704 (fire diamond)
2
0
1
Flash point Non-flammable
Related compounds
Other cations
 Cesium tetrachloridocuprate(II)
ammonium tetrachloridocuprate(II)
rubidium tetrachloridocuprate(II)
iron(II) tetrachloridocuprate(II)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium tetrachloridocuprate(II) describes salts with chemical formula K2CuCl4(H2O)2. It is a greenish blue solid.[1] This form also occurs naturally as the rare mineral mitscherlichite.[1][2]

Synthesis and natural occurrence

The dihydrate occurs rarely in nature near volcanic vents, e.g. in Mount Vesuvius, as the mineral mitscherlichite; which is named in honor of Eilhardt Mitscherlich (1794–1863), the German crystallographer and chemist who first synthesized the compound.[2] It was identified as pigment in some ancient artifacts.[3] The dihydrate can be obtained by slow evaporation of a solution of potassium chloride (KCl) and copper(II) chloride (CuCl
2) in 2:1 molar ratio.[1][4]

Structure

The structure of hydrated potassium tetrachloridocuprate(II) has been confirmed by X-ray crystallography and neutron diffraction. Copper is square planar, being bound to two trans chloride ligands (dCu-Cl = 228 pm and two water ligands (dCu-O = 1.97 pm). The other chlorides are more distant (Cu-Cl = 289 pm).[5] Structural studies on this salt are of historic interest.[1][4][6] The compound is isostructural with (NH4)2CuCl4·2H2O and Rb2CuCl4·2H2O.[1][4][6][7][8]

Tetrachlorocuprates

Anhydrous K2CuCl4 has a complicated history and may not exist. Instead it converts upon heating to a mixture of KCl·CuCl2 and potassium trichloridocuprate KCuCl3.[9][10][7][8][11][12][13][14]

The ion CuCl4]2− has been intensively studied from the perspective of electronic structure. It is a planar complex, usually isolated as a salt with organic cations.[15]

See also

References

  1. ^ a b c d e f Howard E. Swanson, Howard F. McMurdie, Marlene C. Morris, Eloise H. Evans, and Boris Paretzkin (1971) Potassium Copper Chloride Hydrate (mitscherlichite), in [Standard X-ray Diffraction Powder Patterns] National Bureau of Standards, Monograph 25, Section 9; page 34.
  2. ^ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, and Monte C. Nichols (1997) Mitscherlichite, in Handbook of Mineralogy, Mineralogical Society of America. volume III.
  3. ^ Riederer (1982)
  4. ^ a b c Sterling B. Hendricks and Roscoe G. Dickinson (1927). The crystal structures of ammonium, potassium and rubidium cupric chloride dihydrates. Journal of the American Chemical Society, volume 49, issue 9, pages 2149–2162 doi:10.1021/ja01408a005
  5. ^ Chidambaram, R.; Navarro, Q. O.; Garcia, A.; Linggoatmodjo, K.; Shi-Chien, L.; Suh, I. H.; Sequeira, A.; Srikanta, S. (1970). "Neutron diffraction refinement of the crystal structure of potassium copper chloride dihydrate, K2CuCl4.2H2O". Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 26 (6): 827–830. doi:10.1107/S0567740870003187.
  6. ^ a b L. Chrobak (1934). Quantitative spectrometric studies of ammonium and of potassium cupric chloride dihydrate (NH4)2CuCl4.2H2O and K2CuCl4.2H2O. Zeitschrift für Kristallographie, volume 88, pages 35–47
  7. ^ a b E. Joly (1971). C. R. Acad. Sci., Ser. C, volume 271, page 1302.
  8. ^ a b I. V. Vasil'kova and G. M. Barvinok (1966). Chemical Abstracts, volume 65, page 9831.
  9. ^ C. M. Fontana, E. Gorin, G. A. Kidder and C. S. Meredith (1952). Ind. Eng. Chem., volume 44, page 363
  10. ^ S. A. Shchukarev, I. V. Vasil'kova and G. M. Barvinok (1965). Vestn. Leningr. Univ., Ser. Mat. Fiz. Khim., volume 20, page 145.
  11. ^ H. T. Witteveen, D. L. Jongejan and W. Brandwijk (1974). Mater. Res. Bull., volume 9, page 345.
  12. ^ D. W. Smith (1976), Chlorocuprates(II). Coordination Chemistry Reviews, volume 21, issues 2-3, pages 93-158. doi:10.1016/S0010-8545(00)80445-2
  13. ^ N. Fogel and T. J. Nolan (1975). Amer. Chem. Soc. Symp., section Inorg., page 121.
  14. ^ Thomas J. Nolan, Harold Haralson, James L. McAdams and Norman Fogel (1977) Dehydration of potassium tetrachlorocuprate(II) dihydrate. Journal of the Chemical Society, Dalton Transactions, volume 1977, issue 17, pages 1608-1612 doi:10.1039/DT9770001608
  15. ^ Solomon, Edward I. (2006). "Spectroscopic Methods in Bioinorganic Chemistry: Blue to Green to Red Copper Sites". Inorganic Chemistry. 45 (20): 8012–8025. doi:10.1021/ic060450d. PMID 16999398.
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