Samarium (II) bromide

Crystal structure
__ Sm 2+      __ Br -
General
Surname	Samarium (II) bromide
other names	Samarium dibromide
Ratio formula	SmBr 2
Brief description	red-brown solid
External identifiers / databases
CAS number 50801-97-3 PubChem 11833842 ChemSpider 10008489 Wikidata Q16856521
properties
Molar mass	310.17 g mol −1
Physical state	firmly
Melting point	669 ° C
boiling point	1250 ° C
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Samarium (II) bromide is an inorganic chemical compound of samarium from the group of bromides .

Extraction and presentation

Samarium (II) bromide can be obtained by reducing samarium (III) bromide with samarium in a vacuum at 800 to 900 ° C.

${\displaystyle \mathrm {Sm+2\ SmBr_{3}\longrightarrow 3\ SmBr_{2}} }$

It is also possible to produce it by thermal decomposition of samarium (III) bromide at 200 ° C. with relatively large losses due to disproportionation.

${\displaystyle \mathrm {2\ SmBr_{3}\longrightarrow 2\ SmBr_{2}+Br_{2}} }$

The compound was first synthesized in 1934 by Selwood by reducing samarium (III) bromide with hydrogen at 740 ° C.

${\displaystyle \mathrm {2\ SmBr_{3}+H_{2}\longrightarrow 2\ SmBr_{2}+2\ HBr} }$

Synthesis methods from samarium (III) oxide or from lithium bromide and samarium (II) iodide in tetrahydrofuran or by reacting samarium with 1,1,2,2-tetrabromoethane were later developed.

properties

Samarium (II) bromide is a red-brown solid. The connection is extremely hygroscopic and can only be stored and handled under carefully dried protective gas or in a high vacuum. In air or in contact with water, it changes into hydrates while absorbing moisture , but these are unstable and more or less quickly turn into oxide bromides with evolution of hydrogen . The compound has a crystal structure of the strontium bromide type or lead (II) chloride type.

use

Samarium (II) bromide is in organic chemistry, for example, to pinacol - homocoupling of aldehydes and ketones and cross-coupling of carbonyl compounds employed, it has as the commonly used samarium (II) iodide in these reactions better properties. It is used as a reducing agent.

Individual evidence

1. ↑ ^{a b c d e f g} Georg Brauer (Ed.), With the collaboration of Marianne Baudler u. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 1081.
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ^ ^{A b c} David J. Procter, Robert A. Flowers, Troels Skrydstrup: Organic Synthesis Using Samarium Diiodide: A Practical Guide . Royal Society of Chemistry, 2010, ISBN 1-84755-110-6 , pp. 157 ( limited preview in Google Book search).
4. ↑ Andreas P. Zörb: Samarium (II) -halide-mediated alpha-defunctionalization of protected ... Lulu.com, 2010, ISBN 1-4461-2753-2 , p. 62 ( limited preview in Google Book search).