Cobalt(III) chloride or cobaltic chloride is an unstable and elusive compound of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

and

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

with

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

. In this compound, the cobalt atoms have a formal

charge Charge or charged may refer to: Arts, entertainment, and media Films * '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * ''Charge!!'', an album by The Aqu ...

of +3.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. The compound has been reported to exist in the gas phase at high temperatures, in equilibrium with

cobalt(II) chloride Cobalt(II) chloride is an inorganic compound of cobalt and chlorine, with the formula . The compound forms several hydrates ·''n'', for ''n'' = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed.M. T. Saug ...

and chlorine gas.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. It has also been found to be stable at very low temperatures, dispersed in a frozen

argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice a ...

matrix.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. Some articles from the 1920s and 1930s claim the synthesis of bulk amounts of this compound in pure form;C. Schall and H. Markgraf (1924). ''Transactions of the American Electrochemical Society'', volume 45, page 161.D. Hibert and C. Duval (1937): ''Comptes rendues'', volume 204, page 780. however, those results do not seem to have been reproduced, or have been attributed to other substances like the hexachlorocobaltate(III) anion . Those earlier reports claim that it gives green solutions in anhydrous solvents such as

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

and

diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...

, and that it is stable only a very low temperatures (below −60 °C).

Structure and properties

The infrared spectrum of the compound in frozen argon indicates that the isolated molecule is planar with D_''3h'' symmetry. A Scientific study of the stability of this and other metal trihalides at 50 °C was published by Nelsoon and Sharpe in 1956.P. G. Nelsoon 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 50 °C". ''Journal of the Chemical Society A: Inorganic, Physical, Theoretical'', volume 1966,pages 501-511 Aerodynamic properties for the gas phase have been determined by the Glushko Thermocenter of the Russian Academy of Sciences.Scientific Group Thermodata Europe (2001): "Thermodynamic Properties of Compounds, to ". In: ''Landolt-Börnstein - Group IV Physical Chemistry'', Part 3: Compounds from _g to ; volume 19 A3.

Preparation

Cobalts trichlorides was detected in 1952 by

Schäfer Schaefer is an alternative spelling and cognate for the German word ''schäfer'', meaning 'shepherd', which itself descends from the Old High German '' scāphare''. Variants "Shaefer", "Schäfer" (a standardized spelling in many German-speakin ...

and Krehl in the gas phase when

is heated in an atmosphere of chlorine . The trichloride is formed through the equilibrium : 2 + ↔ 2 At 918 K (below the melting point of , 999 K), the trichloride was the predominant cobalt species in the vapor, with partial pressure of 0.72 mm Hg versus 0.62 for the dichloride. However, equilibrium shifts to the left at higher temperatures. At 1073 K, the partial pressures were 7.3 and 31.3 mm Hg, respectively.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. 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 gas + 1/2 = gas". ''Zeitschrift für anorganische und allgemeine Chemie'', volume 283, issue 1‐6, pages 304-313. Cobalt trichloride, in amounts sufficient to study spectroscopically, was obtained by

Green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combin ...

and others in 1983, by

sputtering In physics, sputtering is a phenomenon in which microscopic particles of a solid material are ejected from its surface, after the material is itself bombarded by energetic particles of a plasma or gas. It occurs naturally in outer space, and ca ...

cobalt

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials ...

s with chlorine atoms and trapping the resulting molecules in frozen argon at 14 K. A report from 1969 claims that treatment of solid cobalt(III) hydroxide · with anhydrous ether saturated with at −20 °C produces a green solution (stable at −78 °C) with the characteristic spectrum of . In a 1932 report, the compound was claimed to arise in the electrolysis of cobalt(II) chloride in anhydrous ethanol.C. Schall (1932): "Zur anodischen Oxydation von Co und Ni‐Dichlorid (Nachtrag)." ''Zeitschrift für Elektrochemie'', volume 38, page 27.

Related compounds

The hexachlorocobaltate(III) anion has been identified in preparations of cobalt(III) salts and

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...

in glacial acetic acid. In solutions of cobalt(III) salts with chloride ions, the anionic complexes and are present.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. Trichlorides of cobalt(III) complexed with various ligands, such as organic

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...

s, can be quite stable. In particular,

hexamminecobalt(III) chloride Hexaamminecobalt(III) chloride is the chemical compound with the formula o(NH3)6l3. It is the chloride salt of the coordination complex o(NH3)6sup>3+, which is considered an archetypal "Werner complex", named after the pioneer of coordination c ...

is the archetypal Werner complex and has uses in biological research. Another classical example is

tris(ethylenediamine)cobalt(III) chloride Tris(ethylenediamine)cobalt(III) chloride is an inorganic compound with the formula o(en)3l3 (where "en" is the abbreviation for ethylenediamine). It is the chloride salt of the coordination complex o(en)3sup>3+. This trication was important in ...

References

{{Chlorides Cobalt(III) compounds Inorganic compounds Chlorides Metal halides