Chemistry:Samarium(II) bromide
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| Names | |
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| IUPAC name
samarium(II) bromide
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| Other names
samarium dibromide
dibromosamarium | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
PubChem CID
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| Properties | |
| SmBr2 | |
| Molar mass | 310.17 g/mol[1] |
| Appearance | Brown crystals |
| Melting point | 669 °C (1,236 °F; 942 K)[4] |
| Boiling point | 1,880 °C (3,420 °F; 2,150 K)[citation needed] |
| +5337.0·10−6 cm3/mol [2][3] | |
| Structure | |
| SrBr2[5] | |
| Hazards | |
| GHS pictograms | 
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| GHS Signal word | Warning[1] |
| H315, H319, H335[1] | |
| P261, P305+351+338[1] | |
| Related compounds | |
Other anions
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Samarium(II) chloride Samarium(II) iodide |
Other cations
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Samarium(III) bromide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Samarium(II) bromide is an inorganic compound with the chemical formula SmBr2.[6] It is a brown solid that is insoluble in most solvents but degrades readily in air.[4]
Structure
In the gas phase, SmBr2 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]
References
- ↑ 1.0 1.1 1.2 1.3 "Samarium(II) bromide 99.95% | Sigma-Aldrich". http://www.sigmaaldrich.com/catalog/product/aldrich/431842?lang=en®ion=US.
- ↑ 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.
- ↑ 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. https://archive.org/details/crchandbookofche81lide/page/147.
- ↑ 4.0 4.1 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.
- ↑ 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.
- ↑ Elements, American. "Samarium Bromide SmBr2". https://www.americanelements.com/samarium-bromide-smbr2-50801-97-3.
- ↑ 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.
- ↑ 8.0 8.1 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. https://archive.org/details/organicsynthesis00proc.
- ↑ Ho, Tse-Lok (2016). Fiesers' Reagents for Organic Synthesis Volume 28. John Wiley & Sons. p. 486. ISBN 9781118942819.
- ↑ 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.
- ↑ 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.
- ↑ 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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