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. The compound has few practical applications but is used in laboratories for research on new compounds of samarium.
3D model (JSmol)
CompTox Dashboard (EPA)
|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)|
|92.4 g/100 mL (10 °C)|
|P63/m, No. 176|
|Tricapped trigonal prismatic|
|Occupational safety and health (OHS/OSH):|
|P264, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.
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:
The pentachloride is then heated to 350-400 °C resulting in evolution of ammonium chloride and leaving a residue of the anhydrous trichloride:
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.
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.