Erbium(III) chloride

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Erbium(III) chloride
Erbium(III) chloride hydrate photographed in sunlight
IUPAC name
Erbium(III) chloride
Other names
Erbium trichloride
3D model (Jmol)
ECHA InfoCard 100.030.337
ErCl3 (anhydrous)
ErCl3·6H2O (hexahydrate)
Molar mass 273.62 g/mol (anhydrous)
381.71 g/mol (hexahydrate)
Appearance violet hygroscopic monoclinic crystals (anhydrous)
pink hygroscopic crystals (hexahydrate)
Density 4.1 g/cm3 (anhydrous)
Melting point 776 °C (1,429 °F; 1,049 K) (anhydrous)
decomposes (hexahydrate)
Boiling point 1,500 °C (2,730 °F; 1,770 K)
soluble in water (anhydrous)
slightly soluble in ethanol (hexahydrate)[1]
Related compounds
Other anions
Erbium(III) oxide
Other cations
Holmium(III) chloride, Thulium(III) chloride
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

Erbium(III) chloride, the erbium(III) salt of hydrochloric acid, is a violet solid used for the preparation of erbium metal.


Erbium(III) chloride hydrate photographed under a fluorescent lamp

It is also found as a pink crystalline hexahydrate, CAS number [10025-75-9]. It has the interesting property that the pink colour is much more intense under the light from a fluorescent lamp, as may be seen from the picture.

Anhydrous erbium(III) chloride is formed from the hexahydrate by heating under a strongly chlorinating atmosphere, such as chlorine or hydrogen chloride; otherwise erbium oxide chloride, ErOCl, is formed. An alternative preparation is to react the readily available Er2O3 with excess NH4Cl to make the intermediate salt (NH4)3ErCl6 plus both ammonia and water. This salt is stable with respect to hydrolysis and can be thermally decomposed under vacuum to yield anhydrous erbium(III) chloride with loss of ammonia and gaseous HCl.

It reacts with alkalis to form erbium(III) hydroxide:

ErCl3 + 3 XOH → Er(OH)3 + 3 XCl

Structural data[edit]

Erbium chloride forms crystals of the AlCl3 type, with monoclinic crystals and the point group C2/m.[2]

Erbium(III) chloride hexahydrate also forms monoclinic crystals with the point group of P2/n (P2/c) - C42h. The erbium is octa-coordinated to form [Er(H2O)6Cl2]+ ions with the isolated Cl completing the structure.[3]

Optical properties[edit]

Erbium(III) chloride solutions show a negative nonlinear absorption effect.[4]

Catalytic properties[edit]

Erbium(III) chloride is a powerful catalyst for the acylation of alcohols and phenols, and can be easily recycled and reused without significant loss of activity.[5]


  1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–57. ISBN 0-8493-0594-2. 
  2. ^ Tempelton DH, Carter GF (1954). "The Crystal Structure of Yttrium Trichloride and Similar Compounds". J Phys Chem. 58 (11): 940–943. doi:10.1021/j150521a002. 
  3. ^ Graebner EJ, Conrad GH, Duliere SF (1966). "Crystallographic data for solvated rare earth chlorides". Acta Crystallographica. 21: 1012–1013. doi:10.1107/S0365110X66004420. 
  4. ^ Maeda Y, Akidzuki Y, Yamada T (1998). "All-optical liquid device derived from negative nonlinear absorption effect in an erbium chloride solution". Applied Physics Letters. 73 (17): 2411–2413. doi:10.1063/1.122450. 
  5. ^ CSIRO PUBLISHING - Australian Journal of Chemistry