Chemistry:Dysprosium(III) chloride

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Dysprosium(III) chloride
Dysprosium(III) chloride hexahydrate
IUPAC names
Dysprosium(III) chloride
Dysprosium trichloride
3D model (JSmol)
Molar mass 268.86 g/mol (anhydrous)
Appearance white solid
Density 3.67 g/cm3, solid
Melting point 647 °C (1,197 °F; 920 K) (anhydrous)
Boiling point 1,530 °C (2,790 °F; 1,800 K)
AlCl3 structure
not listed
Flash point Non-flammable
Related compounds
Other anions
Dysprosium(III) fluoride
Dysprosium(III) bromide
Dysprosium(III) iodide
Dysprosium(III) oxide
Other cations
Terbium(III) chloride
Dysprosium(II) chloride
Holmium(III) chloride
Related compounds
Dysprosium(II) 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

Dysprosium(III) chloride (DyCl3), also known as dysprosium trichloride, is a compound of dysprosium and chlorine. It is a white to yellow solid which rapidly absorbs water on exposure to moist air to form a hexahydrate, DyCl3·6H2O. Simple rapid heating of the hydrate causes partial hydrolysis[1] to an oxychloride, DyOCl.

Preparation and reactions

DyCl3 is often prepared by the "ammonium chloride route", starting from either Dy2O3 or the hydrated chloride DyCl3·6H2O.[2][3][4] These methods produce (NH4)2[DyCl5]:

10 NH4Cl + Dy2O3 → 2 (NH4)2[DyCl5] + 6 NH3 + 3 H2O
DyCl3·6H2O + 2 NH4Cl → (NH4)2[DyCl5] + 6 H2O

The pentachloride decomposes thermally according to the following equation:

(NH4)2[DyCl5] → 2 NH4Cl + DyCl3

The thermolysis reaction proceeds via the intermediacy of (NH4)[Dy2Cl7].

Treating Dy2O3 with aqueous HCl produces the hydrated chloride DyCl3·6H2O, which cannot be rendered anhydrous by heating. Instead one obtains an oxychloride:[3]

DyCl3 + H2O → DyOCl + 2 HCl

Dysprosium(III) chloride is a moderately strong Lewis acid, which ranks as "hard" according to the HSAB concept. Aqueous solutions of dysprosium chloride can be used to prepare other dysprosium(III) compounds, for example dysprosium(III) fluoride:

DyCl3 + 3 NaF → DyF3 + 3 NaCl


Dysprosium(III) chloride can be used as a starting point for the preparation of other dysprosium salts. Dysprosium metal is produced when a molten mixture of DyCl3 in eutectic LiCl-KCl is electrolysed. The reduction occurs via Dy2+, at a tungsten cathode.[5]


Dysprosium compounds are believed to be of low to moderate toxicity, although their toxicity has not been investigated in detail.


  1. F. T. Edelmann, P. Poremba, in: Synthetic Methods of Organometallic and Inorganic Chemistry, (W. A. Herrmann, ed.), Vol. 6, Georg Thieme Verlag, Stuttgart, 1997.
  2. Meyer, G. (1989). The Ammonium Chloride Route to Anhydrous Rare Earth Chlorides-The Example of YCl3. Inorganic Syntheses. 25. pp. 146–150. doi:10.1002/9780470132562.ch35. ISBN 978-0-470-13256-2. 
  3. 3.0 3.1 Taylor, M.D.; Carter, C.P. (1962). "Preparation of anhydrous lanthanide halides, especially iodides". Journal of Inorganic and Nuclear Chemistry 24 (4): 387–391. doi:10.1016/0022-1902(62)80034-7. 
  4. Edelmann, F. T.; Poremba, P. (1997). Herrmann, W. A.. ed. Synthetic Methods of Organometallic and Inorganic Chemistry. VI. Stuttgart: Georg Thieme Verlag. ISBN 3-13-103021-6. 
  5. Y. Castrillejo, M. R. Bermejo, A. I. Barrado, R. Pardo, E. Barrado, A. M. Martinez, Electrochimica Acta, 50, 2047-2057 (2005).