Samarium(III) chloride


Samarium(III) chloride, also known as samarium trichloride, is an inorganic compound of samarium and chloride. It is a pale yellow salt that rapidly absorbs water to form a hexahydrate, SmCl3.6H2O.[1] The compound has few practical applications but is used in laboratories for research on new compounds of samarium.

Samarium(III) chloride
UCl3 without caption.png
IUPAC name
samarium(III) chloride
Other names
samarium trichloride
  • 10361-82-7 (anhydrous) checkY
  • 13465-55-9 (hexahydrate) checkY
3D model (JSmol)
  • Interactive image
  • 55428 checkY
ECHA InfoCard 100.030.712 Edit this at Wikidata
EC Number
  • 233-797-0
  • 10131313
  • 5J4QGH7J16 checkY
  • 9874IU4M1V (hexahydrate) checkY
  • DTXSID4047757 Edit this at Wikidata
  • InChI=1S/3ClH.Sm/h3*1H;/q;;;+3/p-3 checkY
  • InChI=1/3ClH.Sm/h3*1H;/q;;;+3/p-3
  • Cl[Sm](Cl)Cl
Molar mass 256.76 g/mol (anhydrous)
364.80 g/mol (hexahydrate)
Appearance pale yellow solid (anhydrous)

cream-coloured solid (hexahydrate)

Density 4.46 g/cm3 (anhydrous)

2.383 g/cm3 (hexahydrate)

Melting point 682 °C (1,260 °F; 955 K)
Boiling point decomposes
92.4 g/100 mL (10 °C)
hexagonal, hP8
P63/m, No. 176
Tricapped trigonal prismatic
Occupational safety and health (OHS/OSH):
Main hazards
GHS labelling:
GHS07: Exclamation mark
H315, H319
P264, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362
Related compounds
Other anions
Samarium(III) fluoride
Samarium(III) bromide
Samarium(III) oxide
Other cations
Samarium(II) chloride
Promethium(III) chloride
Europium(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


Like several related chlorides of the lanthanides and actinides, SmCl3 crystallises in the UCl3 motif. The Sm3+ centres are nine-coordinate, occupying trigonal prismatic sites with additional chloride ligands occupying the three square faces.

Preparation and reactionsEdit

SmCl3 is prepared by the "ammonium chloride" route, which involves the initial synthesis of (NH4)2[SmCl5]. This material can be prepared from the common starting materials at reaction temperatures of 230 °C from samarium oxide:[2]

10 NH4Cl + Sm2O3 → 2 (NH4)2[SmCl5] + 6 NH3 + 3 H2O

The pentachloride is then heated to 350-400 °C resulting in evolution of ammonium chloride and leaving a residue of the anhydrous trichloride:

(NH4)2[SmCl5] → 2 NH4Cl + SmCl3

It can also be prepared from samarium metal and hydrochloric acid.[3][4]

2 Sm + 6 HCl → 2 SmCl3 + 3 H2

Aqueous solutions of samarium(III) chloride can be prepared by dissolving metallic samarium or samarium carbonate in hydrochloric acid.

Samarium(III) chloride is a moderately strong Lewis acid, which ranks as "hard" according to the HSAB concept. Aqueous solutions of samarium chloride can be used to prepare samarium trifluoride:

SmCl3 + 3 KF → SmF3 + 3 KCl


Samarium(III) chloride is used for the preparation of samarium metal, which has a variety of uses, notably in magnets. Anhydrous SmCl3 is mixed with sodium chloride or calcium chloride to give a low melting point eutectic mixture. Electrolysis of this molten salt solution gives the free metal.[5]

In laboratoryEdit

Samarium(III) chloride can also be used as a starting point for the preparation of other samarium salts. The anhydrous chloride is used to prepare organometallic compounds of samarium, such as bis(pentamethylcyclopentadienyl)alkylsamarium(III) complexes.[6]


  1. ^ F. T. Edelmann, P. Poremba (1997). W. A. Herrmann (ed.). Synthetic Methods of Organometallic and Inorganic Chemistry. Vol. 6. Stuttgart: Georg Thieme Verlag.
  2. ^ Meyer, G. (1989). The Ammonium Chloride Route to Anhydrous Rare Earth Chlorides-The Example of YCl3. Inorganic Syntheses. Vol. 25. pp. 146–150. doi:10.1002/9780470132562.ch35. ISBN 978-0-470-13256-2.
  3. ^ L. F. Druding, J. D. Corbett (1961). "Lower Oxidation States of the Lanthanides. Neodymium(II) Chloride and Iodide". J. Am. Chem. Soc. 83 (11): 2462–2467. doi:10.1021/ja01472a010.
  4. ^ J. D. Corbett (1973). "Reduced Halides of the Rare Earth Elements". Rev. Chim. Minérale. 10: 239.
  5. ^ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. ISBN 978-0-08-022057-4.
  6. ^ G. A. Molander, E. D. Dowdy (1999). Shu Kobayashi (ed.). Lanthanides: Chemistry and Use in Organic Synthesis. Berlin: Springer-Verlag. pp. 119–154. ISBN 3-540-64526-8.