Samarium(II) bromide
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IUPAC name
Dibromosamarium
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3D model (JSmol)
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| Properties | |
| SmBr2 | |
| Molar mass | 310.17 g/mol |
| Appearance | Brown crystals |
| Melting point | 669 °C (1,236 °F; 942 K) |
| Boiling point | 1,880 °C (3,420 °F; 2,150 K) |
| +5337.0·10−6 cm3/mol | |
| Hazards | |
| GHS pictograms |  |
| GHS signal word | Warning |
| H315, H319, H335 | |
| P261, P305+351+338 | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Samarium(II) bromide is a crystalline compound with the chemical formula SmBr
2. Samarium(II) bromide is a brown crystal at room temperature.
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.
Samarium(II) bromide is used as a reductant, although it is not used as commonly as samarium diiodide. This is likely due to it being soluble in fewer organic liquids, however, it is an effective reagent 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.
If hexamethylphosphoramide is added to samarium(II) bromide, it will strengthen it enough that it can reduce imines to amines and alkyl chlorides to hydrocarbons. However, the addition of hexamethylphosphoramide to samarium(II) bromide that is in tetrahydrofuran will strengthen it enough that it can reduce cyclohexyl chloride to cyclohexanol, at room temperature, within two hours.
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