Samarium(III) chloride, also known as samarium trichloride, is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

of samarium and chloride. It is a pale yellow salt that rapidly absorbs water to form a hexa

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

, SmCl₃^.6H₂O. 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 mCl₅ This material can be prepared from the common starting materials at reaction temperatures of 230 °C from

samarium oxide Samarium(III) oxide ( Sm2 O3) is a chemical compound. Samarium oxide readily forms on the surface of samarium metal under humid conditions or temperatures in excess of 150°C in dry air. Similar to rust on metallic iron, this oxide layer spalls o ...

: ::10 NH₄Cl + Sm₂O₃ → 2 (NH₄)₂ mCl₅ + 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 mCl₅ → 2 NH₄Cl + SmCl₃ It can also be prepared from samarium metal and hydrochloric acid. :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 A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

, which ranks as "hard" according to the HSAB concept. Aqueous solutions of samarium chloride can be used to prepare

samarium trifluoride Samarium(III) fluoride ( Sm F3) is a slightly hygroscopic solid fluoride. At room temperature, it has orthorhombic structure with space group ''Pnma'' – β-YF3 type with lattice constants ''a'' = 666,9 pm, ''b'' = 705,9 pm, ''c'' = 440,5 pm. ...

: :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 Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...

or calcium chloride to give a low melting point eutectic mixture.

Electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...

of this molten salt solution gives the free metal.

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 Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

compounds of samarium, such as bis(pentamethylcyclopentadienyl)alkylsamarium(III) complexes.

References

{{Lanthanide halides Chlorides Samarium compounds Lanthanide halides