Cobalt(III) chloride

Cobalt(III) chloride
Names
IUPAC name
Cobalt(III) chloride
Other names
Cobaltic chloride
Cobalt trichloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.509
EC Number 233-574-8
Properties
CoCl3
Molar mass 165.2913 g/mol (anhydrous)
Melting point Solid decomposes over -60°C
Solubility soluble in ethanol, diethyl ether
Hazards
GHS pictograms
GHS signal word Danger
H300, H330
P260, P264, P270, P271, P284, P301+310, P304+340, P310, P320, P321, P330, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cobalt(III) chloride or cobaltic chloride is an unstable and elusive compound of cobalt and chlorine with formula CoCl
3. In this compound, the cobalt atoms have a formal charge of +3.[1]

The existence of this compound is still disputed. Reports of its bulk synthesis from the 1920s and 1930s[2][3] do not seem to have been reproduced.[1] However, the compound has been reported to exist in the gas phase[4] and in a frozen argon matrix.[5]

Earlier reports claim that it gives green solutions in anhydrous solvents such as ethanol and diethyl ether, and that it is stable only a very low temperatures (below -60 °C).[6]

Structure and properties

The infrared spectrum of the compound in frozen argon indicates that the isolated CoCl
3 molecule is planar with D3h symmetry.[5]

A theoretical study of the stability of this and other metal trihalides at 25 °C was published by Nelson and Sharpe in 1966.[7]

Thermodynamic properties for the gas phase have been determined by the Glushko Thermocenter of the Russian Academy of Sciences.[8]

Preparation

In a 1932 report, the compound was claimed to arise in the electrolysis of cobalt(II) chloride in anhydrous ethanol.[6]

A report from 1969 claims that treatment of solid cobalt(III) hydroxide CoOOH·H
2O with anhydrous ether saturated with HCl at -20 °C produces a green solution (stable at -78 °C) with the characteristic spectrum of CoCl
3.[1]

Another report from 1952 describes the formation of CoCl
3 in the gas phase when cobalt(II) chloride CoCl
2 is heated in an atmosphere of chlorine Cl
2, through the equilibrium

2CoCl
2 + Cl
2 ↔ 2 CoCl
3

The trichloride was found to be the predominant cobalt species at 918 K, but the equilibrium shifts to the left at higher temperatures.[4][9][10]

The compound was also prepared by sputtering cobalt electrodes with chlorine atoms and trapping the resulting molecules in frozen argon at 14 K.[5]

The hexachlorocobaltate(III) anion CoCl3−
6 has been identified in preparations of cobalt(III) salts and hydrochloric acid HCl in glacial acetic acid.[1]

In solutions of cobalt(III) salts with chloride ions, the anionic complexes (H
2O)
5Cl2+
 and (H
2O)
4(OH)Cl+
 are present.[11]

Trichlorides of cobalt(III) complexed with various ligands, such as organic amines, can be quite stable. In particular, hexamminecobalt(III) chloride Co(NH
3)
6Cl
3 is the archetypal Werner complex and has uses in biological research. Another classical example is tris(ethylenediamine)cobalt(III) chloride Co(H
2N–C
2H
4–NH
2)
3Cl
3.

References

  1. 1 2 3 4 Arthur W. Chester, El-Ahmadi Heiba, Ralph M. Dessau, and William J. Koehl Jr. (1969): "The interaction of cobalt(III) with chloride ion in acetic acid". Inorganic and Nuclear Chemistry Letters, volume 5, issue 4, pages 277-283. doi:10.1016/0020-1650(69)80198-4
  2. ↑ C. Schall and H. Markgraf (1924). Transactions of the American Electrochemical Society, volume 45, page 161.
  3. ↑ D. Hibert and C. Duval (1937): Comptes rendues, volume 204, page 780.
  4. 1 2 Harald Schäfer and Kurt Krehl (1952): "Das gasförmige Kobalt(III)‐chlorid und seine thermochemischen Eigenschaften". Zeitschrift für anorganische und allgemeine Chemie, volume 268, issue 1‐2, pages 25-34. doi:10.1002/zaac.19522680105
  5. 1 2 3 David W. Green, Dana P. McDermott, and Adelle Bergman (1983): "Infrared spectra of the matrix-isolated chlorides of iron, cobalt, and nickel." Journal of Molecular Spectroscopy, volume 98, issue 1, pages 111-124. doi:10.1016/0022-2852(83)90206-0
  6. 1 2 C. Schall (1932): "Zur anodischen Oxydation von Co und Ni‐Dichlorid (Nachtrag)." Zeitschrift für Elektrochemie, volume 38, page 27.
  7. ↑ P. G. Nelson and A. G. Sharpe (1966): "The variations in the thermal stabilities of the trichlorides, tribromides, and tri-iodides of the metals of the first transition series at 25 °C". Journal of the Chemical Society A: Inorganic, Physical, Theoretical, volume 1966,pages 501-511 doi:10.1039/J19660000501
  8. ↑ Scientific Group Thermodata Europe (2001): "Thermodynamic Properties of Compounds, CoCl
    3     to {[chem|NpCl|3}}". In: Landolt-Börnstein - Group IV Physical Chemistry, Part 3: Compounds from CoCl
    3    g to Ge
    3    N
    4    ; volume 19 A3. doi:10.1007/10551582_3 ISBN 978-3-540-66796-4
  9. ↑ Harald Schäfer and Günther Breil (1956): "Über die Neigung zur Bildung gasförmiger Trichloride bei den Elementen Cr, Mn, Fe, Co, Ni, untersucht mit der Reaktion MeCl
    2     gas + 1/2 Cl
    2     = MeCl
    3     gas". Zeitschrift für anorganische und allgemeine Chemie, volume 283, issue 1‐6, pages 304-313. doi:10.1002/zaac.19562830130
  10. ↑ W. D. Halstead (1975): "A review of saturated vapour pressures and allied data for the principal corrosion products of iron, chromium, nickel and cobalt in flue gases." Corrosion Science, volume 15, issues 6–12, pages 603-625. doi:10.1016/0010-938X(75)90027-X
  11. ↑ T. J. Conocchioli, G. H. Nancollas, and N. Sutin (1965): "The kinetics of the formation and dissociation of the monochloro complex of cobalt(III)". Inorganic Chemistry, volume 5, issue 1, pages 1-5. doi:10.1021/ic50035a001
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