Potassium tetrachloridocuprate(II)

Chemical compound From Wikipedia, the free encyclopedia

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]

Quick facts Names, Identifiers ...
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:
GHS05: CorrosiveGHS06: ToxicGHS07: Exclamation markGHS09: Environmental hazard
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
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).
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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

Structure of K
2CuCl
4·2H
2O (mitscherlichite).

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

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