Iron(II) bromide
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| Names | |
|---|---|
| IUPAC name
Iron(II) bromide | |
| Other names
Ferrous bromide | |
| Identifiers | |
7789-46-0  | |
| ChemSpider | 74218 |
| |
| Jmol-3D images | Image |
| PubChem | 659170 |
| |
| Properties | |
| FeBr2 | |
| Molar mass | 215.65 g mol−1 |
| Appearance | yellow-brown solid |
| Density | 4.63 g cm−3, solid |
| Melting point | 684 °C (1,263 °F; 957 K) |
| Boiling point | 934 °C (1,713 °F; 1,207 K) |
| soluble | |
| Solubility in other solvents | THF, methanol, ethanol |
| Structure | |
| Crystal structure | Rhombohedral, hP3, SpaceGroup = P-3m1, No. 164 |
| octahedral | |
| Hazards | |
| Main hazards | none |
| R-phrases | R20 R36/37/38 |
| S-phrases | S26 S36 |
| Related compounds | |
| Other anions |
Iron(II) chloride |
| Other cations |
iron(III) bromide |
| Related compounds |
VBr2 |
| Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
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| Infobox references | |
Iron(II) bromide is the chemical compound with the chemical formula FeBr2. This brownish-colored solid is a useful synthetic intermediate; for example it is employed to insert Fe(II) into porphyrins.
Structure
Like most metal halides, FeBr2 adopts a polymeric structure consisting of isolated metal centers cross-linked with halides. It crystallizes with the CdI2 structure, featuring close-packed layers of bromide ions, between which are located Fe(II) ions in octahedral holes.[1] The packing of the halides is slightly different from that for FeCl2, which adopts the CdCl2 motif. FeBr2 also forms hydrates.
Synthesis
FeBr2 is conveniently synthesized using a methanol solution of concentrated hydrobromic acid. Addition with Fe gives the methanol solvate [Fe(MeOH)6]Br2 together with hydrogen gas. Heating the methanol complex in a vacuum at ca. 160 °C gives pure FeBr2.[2]
Iron(II) bromide cannot be formed by the reaction of iron and bromine, because that reaction would produce ferric bromide.
Reactions
FeBr2 reacts with 2 equivalents of (C2H5)4NBr to give [(C2H5)4N]2FeBr4.[3]
FeBr2 reacts with bromide and bromine to form the intensely colored, mixed-valence species [FeBr3Br9]−.[4]
FeBr2 is a weak reducing agent, as are all ferrous compounds.
References
- ↑ Haberecht, J.; Borrmann, H.; Kniep, R. "Refinement of the Crystal Structure of Iron Dibromide, FeBr2 Zeitschrift für Kristallographie - New Crystal Structures (2001), volume 216, page 510.
- ↑ G. Winter, "Iron(II) Halides" in "Inorganic Syntheses" 1973, volume 14, pages 101-104.
- ↑ N. S. Gill, F.. B. Taylor Inorganic Syntheses 1967, volume 9, page 136-142.
- ↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5
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