Potassium trichloridocuprate(II)

Potassium trichloridocuprate(II) is a salt with chemical formula KCuCl3, more properly [K+]2[Cu2Cl2−6].[3][4]

potassium trichloridocuprate(II)
Names
Other names
    • potassium trichlorocuprate(II)
    • potassium copper(II) trichloride
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 237-639-1
  • InChI=1S/3ClH.Cu.K/h3*1H;;/q;;;+2;+1/p-3
    Key: SZNHAWRQQIZIBK-UHFFFAOYSA-K
  • Cl[Cu-](Cl)Cl.[K+]
Properties
KCuCl3
Molar mass 208.99 g·mol−1
Appearance garnet-red crystals[1]
Density 2.86 g/cm3[1]
Solubility methanol,[2] ethanol[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

It is a member of the "halide" sub-family of perovskite materials with general formula ABX3 where A is a monovalent cation, B is a divalent cation, and X is a halide anion.[5]

The compound occurs in nature as the bright red mineral sanguite.[1]

The compound is also called potassium trichlorocuprate(II), potassium copper(II) trichloride, potassium cupric chloride and other similar names. The latter is used also for potassium tetrachloridocuprate(II) K2CuCl4.[1]

Preparation and properties

The compound can be obtained by evaporation of a solution of potassium chloride KCl and copper(II) chloride CuCl2 in 1:1 mole ratio.[3]

The anhydrous form is garnet-red.[6] It can be crystallized from a molten mixture of potassium chloride KCl and copper(II) chloride CuCl2.[7][2] or by evaporation from a solution of the salts in ethanol.[5] It is very hygroscopic,[5] and soluble in methanol and ethanol.[2] It is antiferromagnetic below 30 K, and pleochroic, with maximum visible absorption when the electric vector is parallel to the Cu–Cu vector of the dimer.[6][8]

Structure

Anhydrous

The anhydrous mineral form (sanguite) has the monoclinic crystal structure, with symmetry group P21/c and lattice parameters a = 402.81 pm, b = 1379.06 pm, c = 873.35 pm, and β = 97.137°, cell volume V = 0.48138 nm3, and formulas per cell Z = 4.[1][9] The measured density is 2.86 g/cm3, close to the calculated one 2.88 g/cm3. It contains discrete almost planar anions [Cu2Cl6]2−, each with the two copper atoms connected by two bridging chlorine atoms. These anions are arranged in columns consisting of distorted edge-sharing CuCl6 octahedra, stacked in double chains parallel to the a axis. The columns occupy the edges and the centre of the cell's projection on the bc plane.[1][9][6] The potassium atoms are located between these columns; each K+ cation is surrounded by nine chlorine atoms.[1] The mineral is optically biaxial (negative), with α = 1.653, β = 1.780, γ = 1.900', 2V= 85°. The mineral is named from the Latin sanguis (blood), alluding to its color.[1]

Theoretical calculations for this topology give the lattice parameters as a = 1388.1 pm, b = 427.7 pm, c = 896.5 pm, α = 79.855°, cell volume V = 0.523891 nm3, calculated density 2.65 g/cm3.[10]

Theoretical

An alternative theoretical structure for the compound has a cubic crystal system, symmetry group Pm3m[221], with the copper atoms arranged as corners of a cubic grid, a potassium atom at the center of each cube and a chlorine atom at the midpoint of each edge. The latice parameters are a = b = c = 485.8 pm, V = 0.114684 nm3, predicted density 3.03 g/cm3.[11]

References
  1. Pekov, Igor V.; Zubkova, Natalia V.; Belakovskiy, Dmitry I.; Lykova, Inna S.; Yapaskurt, Vasiliy O.; Vigasina, Marina F.; Sidorov, Evgeny G.; Pushcharovsky, Dmitry Yu. (2015). "Sanguite, KCuCl3, A New Mineral from the Tolbachik Volcano, Kamchatka, Russia". The Canadian Mineralogist. 53 (4): 633–641. doi:10.3749/canmin.1500012.
  2. Kuroe, H.; Takami, N.; Niwa, N.; Sekine, T.; Matsumoto, M.; Yamada, F.; Tanaka, H.; Takemura, K. (2012). "Longitudinal magnetic excitation in KCuCl3 studied by Raman scattering under hydrostatic pressures". Journal of Physics: Conference Series. 400 (3): 032042. arXiv:1209.0235. Bibcode:2012JPhCS.400c2042K. doi:10.1088/1742-6596/400/3/032042. S2CID 96200315.
  3. Smith, D.W. (1976). "Chlorocuprates(II)". Coordination Chemistry Reviews. 21 (2–3): 93–158. doi:10.1016/S0010-8545(00)80445-2.
  4. "Potassium trichlorocuprate(1-)". Chemical page 44145367 at the PubChem website. Accessed on 2022-07-18.
  5. McMurdie, H.F.; De Groot, J.; Morris, M.; Swanson, H.E. (1969). "Crystallography and preparation of some ABCl3 compounds". Journal of Research of the National Bureau of Standards Section A. 73A (6): 621. doi:10.6028/jres.073A.049.
  6. Willett, Roger D.; Dwiggins, Claudius; Kruh, R. F.; Rundle, R. E. (1963). "Crystal Structures of KCuCl3 and NH4CuCl3". The Journal of Chemical Physics. 38 (10): 2429–2436. Bibcode:1963JChPh..38.2429W. doi:10.1063/1.1733520.
  7. Kato, T.; Oosawa, A.; Takatsu, K.; Tanaka, H.; Shiramura, W.; Nakajima, K.; Kakurai, K. (1999). "Magnetic excitations in the spin gap system KCuCl3 and TlCuCl3". Journal of Physics and Chemistry of Solids. 60 (8–9): 1125–1128. Bibcode:1999JPCS...60.1125K. doi:10.1016/S0022-3697(99)00072-4.
  8. Cavadini, N.; Henggeler, W.; Furrer, A.; Güdel, H.-U.; Krämer, K.; Mutka, H. (1999). "Magnetic excitations in the quantum spin system KCuCl". The European Physical Journal B. 7 (4): 519–522. Bibcode:1999EPJB....7..519C. doi:10.1007/s100510050642. S2CID 115539179.
  9. Cavadini, N.; Heigold, G.; Henggeler, W.; Furrer, A.; Güdel, H-U; Krämer, K.; Mutka, H. (2000). "Quantum magnetic interactions in S = 1/2 KCuCl3". Journal of Physics: Condensed Matter. 12 (25): 5463–5472. Bibcode:2000JPCM...12.5463C. doi:10.1088/0953-8984/12/25/310. S2CID 250757988.
  10. None Available (2020). "Materials Data on KCuCl3 by Materials Project". LBNL Materials Project; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). doi:10.17188/1201674. {{cite journal}}: Cite journal requires |journal= (help)
  11. None Available (2017). "Materials Data on KCuCl3 (SG:221) by Materials Project". LBNL Materials Project; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). doi:10.17188/1354951. {{cite journal}}: Cite journal requires |journal= (help)
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