Samarium(II) bromide

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Samarium(II) bromide
Strontium-bromide-xtal-2011-Mercury-3D-balls.png
Names
IUPAC name
samarium(II) bromide
Other names
samarium dibromide
dibromosamarium
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/2BrH.Sm/h2*1H;/q;;+2/p-2
    Key: AEPYKHCUOAUXAI-UHFFFAOYSA-L
  • Br[Sm]Br
Properties
SmBr2
Molar mass 310.17 g/mol [1]
AppearanceBrown crystals
Melting point 669 °C (1,236 °F; 942 K) [2]
Boiling point 1,880 °C (3,420 °F; 2,150 K)[ citation needed ]
+5337.0·10−6 cm3/mol [3] [4]
Structure
SrBr2 [5]
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Warning [1]
H315, H319, H335 [1]
P261, P305+P351+P338 [1]
Related compounds
Other anions
Samarium(II) chloride
Samarium(II) iodide
Other cations
Samarium(III) bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Samarium(II) bromide is an inorganic compound with the chemical formula SmBr
2. [6] It is a brown solid that is insoluble in most solvents but degrades readily in air. [2]

Contents

Structure

In the gas phase, SmBr
2 is a bent molecule with Sm–Br distance 274.5  pm and bond angle 131±6°. [7]

History

Samarium(II) bromide was first synthesized in 1934 by P. W. Selwood, when he reduced samarium tribromide (SmBr3) with hydrogen (H2). Kagan also synthesized it by converting samarium(III) oxide (Sm2O3) to SmBr3 and then reducing with a lithium dispersion in THF. Robert A. Flowers synthesized it by adding two equivalent of lithium bromide (LiBr) to samarium diiodide (SmI2) in tetrahydrofuran. Namy managed to synthesize it by mixing tetrabromoethane (C2H2Br4) with samarium metal, and Hilmerson found that heating the tetrabromoethane or samarium greatly improved the production of samarium(II) bromide. [8]

Reactions

Samarium(II) bromide has reducing properties reminiscent of the more commonly used samarium diiodide. [9] It is an effective for pinacol homocouplings of aldehydes, ketones, and cross-coupling carbonyl compounds. Reports have shown that samarium(II) bromide is capable of selectively reducing ketones if it is in the presence of an alkyl halide. [8]

Samarium(II) bromide forms soluble adducts with hexamethylphosphoramide. This species reduces imines to amines and alkyl chlorides to hydrocarbons. [10] For example, SmBr2(hmpa)x converts cyclohexyl chloride to cyclohexane. [11]

Samarium(II) bromide will reduce ketones in tetrahydrofuran if an activator is absent. [12]

Related Research Articles

<span class="mw-page-title-main">Samarium</span> Chemical element, symbol Sm and atomic number 62

Samarium is a chemical element; it has symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of samarium(II) are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II) iodide.

<span class="mw-page-title-main">Samarium(II) iodide</span> Chemical compound

Samarium(II) iodide is an inorganic compound with the formula SmI2. When employed as a solution for organic synthesis, it is known as Kagan's reagent. SmI2 is a green solid and solutions are green as well. It is a strong one-electron reducing agent that is used in organic synthesis.

<span class="mw-page-title-main">Hydrogen bromide</span> Chemical compound

Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.

<span class="mw-page-title-main">Hexamethylphosphoramide</span> Chemical compound

Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula [(CH3)2N]3PO. This colorless liquid is a useful reagent in organic synthesis.

<span class="mw-page-title-main">Iron(III) bromide</span> Chemical compound

Iron(III) bromide is the chemical compound with the formula FeBr3. Also known as ferric bromide, this red-brown odorless compound is used as a Lewis acid catalyst in the halogenation of aromatic compounds. It dissolves in water to give acidic solutions.

<span class="mw-page-title-main">Aluminium bromide</span> Chemical compound

Aluminium bromide is any chemical compound with the empirical formula AlBrx. Aluminium tribromide is the most common form of aluminium bromide. It is a colorless, sublimable hygroscopic solid; hence old samples tend to be hydrated, mostly as aluminium tribromide hexahydrate (AlBr3·6H2O).

<span class="mw-page-title-main">Arsenic tribromide</span> Chemical compound

Arsenic tribromide is an inorganic compound with the formula AsBr3, it is a bromide of arsenic. Arsenic is a chemical element that has the symbol As and atomic number 33. This pyramidal molecule is the only known binary arsenic bromide. AsBr3 is noteworthy for its very high refractive index of approximately 2.3. It also has a very high diamagnetic susceptibility. It is a poisonous metalloid that has many allotropic forms: yellow and several black and gray forms (metalloids), orthorhombic prisms, colorless rhombic crystals are a few that are seen. Bromine is a halogen element with the symbol Br and atomic number 35. Diatomic bromine does not occur naturally, but bromine salts can be found in crustal rock.

<span class="mw-page-title-main">Copper(II) bromide</span> Chemical compound

Copper(II) bromide (CuBr2) is a chemical compound that forms an unstable tetrahydrate CuBr2·4H2O. It is used in photographic processing as an intensifier and as a brominating agent in organic synthesis.

<span class="mw-page-title-main">Gallium(III) bromide</span> Chemical compound

Gallium(III) bromide (GaBr3) is a chemical compound, and one of four gallium trihalides.

Tin(II) bromide is a chemical compound of tin and bromine with a chemical formula of SnBr2. Tin is in the +2 oxidation state. The stability of tin compounds in this oxidation state is attributed to the inert pair effect.

<span class="mw-page-title-main">Indium(III) bromide</span> Chemical compound

Indium(III) bromide, (indium tribromide), InBr3, is a chemical compound of indium and bromine. It is a Lewis acid and has been used in organic synthesis.

<span class="mw-page-title-main">Caesium bromide</span> Chemical compound

Caesium bromide or cesium bromide is an ionic compound of caesium and bromine with the chemical formula CsBr. It is a white or transparent solid with melting point at 636 °C that readily dissolves in water. Its bulk crystals have the cubic CsCl structure, but the structure changes to the rocksalt type in nanometer-thin film grown on mica, LiF, KBr or NaCl substrates.

<span class="mw-page-title-main">Nickel(II) bromide</span> Chemical compound

Nickel(II) bromide is the name for the inorganic compounds with the chemical formula NiBr2(H2O)x. The value of x can be 0 for the anhydrous material, as well as 2, 3, or 6 for the three known hydrate forms. The anhydrous material is a yellow-brown solid which dissolves in water to give blue-green hexahydrate (see picture).

Organobromine chemistry is the study of the synthesis and properties of organobromine compounds, also called organobromides, which are organic compounds that contain carbon bonded to bromine. The most pervasive is the naturally produced bromomethane.

<span class="mw-page-title-main">Reductions with samarium(II) iodide</span>

Reductions with samarium(II) iodide involve the conversion of various classes of organic compounds into reduced products through the action of samarium(II) iodide, a mild one-electron reducing agent.

<span class="mw-page-title-main">Chromium(III) bromide</span> Chemical compound

Chromium(III) bromide is an inorganic compound with the chemical formula CrBr3. It is a dark colored solid that appears green in transmitted light but red with reflected light. It is used as a precursor to catalysts for the oligomerization of ethylene.

Samarium(III) bromide is a crystalline compound of one samarium and three bromine atoms with the chemical formula of SmBr3. Samarium(III) bromide is a dark brown powder at room temperature. The compound has a crystal structure isotypic to that of plutonium(III) bromide.

Holmium(III) bromide is a crystalline compound made of one holmium atom and three bromine atoms. Holmium bromide is a yellow powder at room temperature. Holmium bromide is hygroscopic. Holmium bromide is odorless.

<span class="mw-page-title-main">Cyanogen azide</span> Chemical compound

Cyanogen azide, N3CN or CN4, is an azide compound of carbon and nitrogen which is an oily, colourless liquid at room temperature. It is a highly explosive chemical that is soluble in most organic solvents, and normally handled in dilute solution in this form. It was first synthesised by F. D. Marsh at DuPont in the early 1960s. There had been earlier claims of discovering it as a crystalline solid, which were incorrect.

Samarium compounds are compounds formed by the lanthanide metal samarium (Sm). In these compounds, samarium generally exhibits the +3 oxidation state, such as SmCl3, Sm(NO3)3 and Sm(C2O4)3. Compounds with samarium in the +2 oxidation state are also known, for example SmI2.

References

  1. 1 2 3 4 "Samarium(II) bromide 99.95% | Sigma-Aldrich". www.sigmaaldrich.com. Retrieved 20 December 2016.
  2. 1 2 Haynes, William M. (2013). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (94th ed.). CRC Press. p. 86. ISBN   9781466571150.
  3. ↑ Haynes, William M. (2013). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (94th ed.). CRC Press. p. 135. ISBN   9781466571150.
  4. ↑ Lide, David R. (2004). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (85th ed.). Boca Raton [u.a.]: CRC Press. p.  147. ISBN   9780849304859.
  5. ↑ Sass, Ronald L.; Brackett, Thomas; Brackett, Elizabeth (December 1963). "The Crystal Structure of Strontium Bromide". The Journal of Physical Chemistry. 67 (12): 2862–2863. doi:10.1021/j100806a516.
  6. ↑ Elements, American. "Samarium Bromide SmBr2". American Elements. Retrieved 20 December 2016.
  7. ↑ Ezhov, Yu. S.; Sevast'yanov, V. G. (January 2004). "Molecular Structure of Samarium Dibromide". Journal of Structural Chemistry. 45 (1): 160–164. doi:10.1023/B:JORY.0000041516.14569.9c. S2CID   96049918.
  8. 1 2 Skrydstrup, David J. Procter, Robert A. Flowers, Troels (2009). Organic synthesis using samarium diiodide a practical guide . Cambridge: Royal Society of Chemistry. p.  157. ISBN   9781847551108.{{cite book}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Ho, Tse-Lok (2016). Fiesers' Reagents for Organic Synthesis Volume 28. John Wiley & Sons. p. 486. ISBN   9781118942819.
  10. ↑ Pecharsky, Vitalij K.; Bünzli, Jean-Claude G.; Gschneidner, Karl A. (2006). Handbook on the physics and chemistry of rare earths. Amsterdam: North Holland Pub. Co. p. 431. ISBN   9780080466729.
  11. ↑ Couty, Sylvain; Baird, Mark S.; Meijere, Armin de; Chessum, Nicola; Dzielendziak, Adam (2014). Science of Synthesis: Houben-Weyl Methods of Molecular Transformations Vol. 48: Alkanes. Georg Thieme Verlag. p. 153. ISBN   9783131722911.
  12. ↑ Brown, Richard; Cox, Liam; Eames, Jason; Fader, Lee (2014). Science of Synthesis: Houben-Weyl Methods of Molecular Transformations Vol. 36: Alcohols. Georg Thieme Verlag. p. 129. ISBN   9783131721310.
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