Samarium(III) chloride
Encyclopedia
Samarium chloride (SmCl3), also known as samarium trichloride, is a compound of samarium
and chlorine
. It is a pale yellow solid which rapidly absorbs water on exposure to moist air to form a hexahydrate
, SmCl3.6H2O. Simple rapid heating of the hydrate
alone may cause small amounts of hydrolysis
. The first five moles of water are lost at 110 °C.
, which ranks as "hard" according to the HSAB concept. Aqueous solutions of samarium chloride can be used to prepare insoluble samarium(III) compounds, for example samarium(III) hydroxide or samarium(III) fluoride
:
metal or samarium(III) carbonate and hydrochloric acid
. The anhydrous
halide
may alternatively be prepared from samarium
metal and hydrogen chloride
.
Anhydrous
SmCl3 can be made by dehydration of the hydrate either by slowly heating to 400 °C with 4-6 equivalents of ammonium chloride
under high vacuum, or by heating with an excess of thionyl chloride
for five hours. The anhydrous
halide
may alternatively be prepared from samarium
metal and hydrogen chloride
. It is usually purified by high temperature sublimation under high vacuum.
metal (which has a variety of uses, notably in magnet
s). Anhydrous SmCl3 is mixed with sodium chloride
or calcium chloride
to lower the melting point
, then it is melted and electrolysed
to give the free metal
. The anhydrous chloride
may also be used to prepare organometallic compounds of samarium, such as bis(pentamethylcyclopentadienyl)alkylsamarium(III) complexes used as catalysts for hydrogenation
and hydrosilylation
of alkene
s. Samarium(III) chloride can also be used as a starting point for the preparation of other samarium
salt
s.
Samarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
and chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
. It is a pale yellow solid which rapidly absorbs water on exposure to moist air to form a hexahydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
, SmCl3.6H2O. Simple rapid heating of the hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
alone may cause small amounts of hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
. The first five moles of water are lost at 110 °C.
Chemical properties
Samarium(III) chloride is a moderately strong Lewis acidLewis acid
]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...
, which ranks as "hard" according to the HSAB concept. Aqueous solutions of samarium chloride can be used to prepare insoluble samarium(III) compounds, for example samarium(III) hydroxide or samarium(III) fluoride
Samarium(III) fluoride
Samarium fluoride is a slightly hygroscopic solid fluoride.At room temperature, it has orthorhombic structure with space group Pnma - β-YF3 type with lattice constants a = 6.669, b = 7.059, c = 4.405...
:
- SmCl3(aq) + 3 NaOH(aq) → Sm(OH)3(s) + 3 NaCl(aq)
- SmCl3(aq) + 3 KF(aq) → SmF3(s) + 3 KCl(aq)
Preparation
Samarium(III) chloride can be prepared as a yellow aqueous solution by reaction of either samariumSamarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
metal or samarium(III) carbonate and hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
. The anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
halide
Halide
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
may alternatively be prepared from samarium
Samarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
metal and hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
.
- 2 Sm(s) + 6 HCl(aq) → 2 SmCl3(aq) + 3 H2(g)
- Sm2(CO3)3(s) + 6 HCl(aq) → 2 SmCl3(aq) + 3 CO2(g)Carbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
+ 3 H2O(l)WaterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
Anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
SmCl3 can be made by dehydration of the hydrate either by slowly heating to 400 °C with 4-6 equivalents of ammonium chloride
Ammonium chloride
Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...
under high vacuum, or by heating with an excess of thionyl chloride
Thionyl chloride
Thionyl chloride is an inorganic compound with the formula SOCl2. It is a reactive chemical reagent used in chlorination reactions. It is a colorless, distillable liquid at room temperature and pressure that decomposes above 140 °C. Thionyl chloride is sometimes confused with sulfuryl...
for five hours. The anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
halide
Halide
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
may alternatively be prepared from samarium
Samarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
metal and hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
. It is usually purified by high temperature sublimation under high vacuum.
Uses
Samarium(III) chloride is used for the preparation of samariumSamarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
metal (which has a variety of uses, notably in magnet
Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...
s). Anhydrous SmCl3 is mixed with sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...
or calcium chloride
Calcium chloride
Calcium chloride, CaCl2, is a salt of calcium and chlorine. It behaves as a typical ionic halide, and is solid at room temperature. Common applications include brine for refrigeration plants, ice and dust control on roads, and desiccation...
to lower the melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
, then it is melted and electrolysed
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
to give the free metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
. The anhydrous chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
may also be used to prepare organometallic compounds of samarium, such as bis(pentamethylcyclopentadienyl)alkylsamarium(III) complexes used as catalysts for hydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...
and hydrosilylation
Hydrosilylation
Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds. Ordinarily the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and...
of alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
s. Samarium(III) chloride can also be used as a starting point for the preparation of other samarium
Samarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s.