Iron(II) bromide

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Iron(II) bromide
Iron(II) bromide
Names
IUPAC name
Iron(II) bromide
Other names
Ferrous bromide
Identifiers
7789-46-0 YesY
ChemSpider 74218 YesY
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 otherwise noted, data are 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[edit]

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[edit]

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[edit]

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[edit]

  1. ^ 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.
  2. ^ G. Winter, "Iron(II) Halides" in "Inorganic Syntheses" 1973, volume 14, pages 101-104.
  3. ^ N. S. Gill, F.. B. Taylor Inorganic Syntheses 1967, volume 9, page 136-142.
  4. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5