Samarium(III) chloride

Samarium(III) chloride
Names
	IUPAC name samarium(III) chloride
	Other names samarium trichloride; trichlorosamarium
Identifiers
CAS Number	10361-82-7 (anhydrous) ; 13465-55-9 (hexahydrate) ;
3D model (JSmol)	Interactive image;
ChemSpider	55428 ;
ECHA InfoCard	100.030.712
EC Number	233-797-0;
PubChem CID	10131313;
UNII	5J4QGH7J16 ; 9874IU4M1V (hexahydrate) ;
CompTox Dashboard (EPA)	DTXSID4047757 ;
	InChI InChI=1S/3ClH.Sm/h31H;/q;;;+3/p-3 Key: BHXBZLPMVFUQBQ-UHFFFAOYSA-K ; InChI=1/3ClH.Sm/h31H;/q;;;+3/p-3 Key: BHXBZLPMVFUQBQ-DFZHHIFOAZ;
	SMILES Cl[Sm](Cl)Cl;
Properties
Chemical formula	SmCl3
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
Solubility in water	92.4 g/100 mL (10 °C)
Structure
Crystal structure	hexagonal, hP8
Space group	P63/m, No. 176
Coordination geometry	Tricapped trigonal prismatic; (nine-coordinate)
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Irritant
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319
Precautionary statements	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). verify (what is ?) Infobox references

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.

Structure

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 reactions

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

Uses

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 laboratory

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]

References

^ F. T. Edelmann, P. Poremba (1997). W. A. Herrmann (ed.). Synthetic Methods of Organometallic and Inorganic Chemistry. Vol. 6. Stuttgart: Georg Thieme Verlag.
^ Meyer, G. (1989). "The Ammonium Chloride Route to Anhydrous Rare Earth Chlorides—The Example of Ycl ₃". 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.
^ 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.
^ J. D. Corbett (1973). "Reduced Halides of the Rare Earth Elements". Rev. Chim. Minérale. 10: 239.
^ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. ISBN 978-0-08-022057-4.
^ 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.

[edelmann-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 Ycl ₃". 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.

[corbett1-3] 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.

[corbett2-4] 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.

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