Iron(II) bromide

Chembox new
Name = Iron(II) bromide
ImageFile = Iron(II) bromide.jpg
ImageName = Iron(II) bromide
IUPACName = Iron(II) bromide
OtherNames = Ferrous bromide
Section1 = Chembox Identifiers
CASNo = 7789-46-0
RTECS =
Section2 = Chembox Properties
Formula = FeBr₂
MolarMass = 215.65 g/mol
Appearance = yellow-brown solid
Density = 4.63 g/cm³, solid
Solubility = soluble
Solvent = other solvents
SolubleOther = THF, methanol, ethanol
MeltingPt = 684 °C
BoilingPt = 934 °C
Section3 = Chembox Structure
Coordination = octahedral in solid state
CrystalStruct = CdI₂
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = none
FlashPt =
RPhrases = 20-36/37/38
SPhrases = 26-36
Section8 = Chembox Related
OtherAnions = Iron(II) chloride
OtherCations = iron(III) bromide
Function = compounds
OtherFunctn = VBr₂

Iron(II) bromide is the chemical compound FeBr₂. This brownish-colored solid is a useful synthetic intermediate; for example it is employed to insert Fe(II) into porphyrins.

tructure

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. [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.] The packing of the halides is slightly different from that for FeCl₂, which adopts the CdCl₂ motif. FeBr₂ also forms hydrates.

ynthesis

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. [G. Winter, "Iron(II) Halides" in "Inorganic Syntheses" 1973, volume 14, pages 101-104.]

Reactions

FeBr₂ reacts with (C₂H₅)₄NBr to give [(C₂H₅)₄N] ₂FeBr₄. [N. S. Gill, F.. B. Taylor Inorganic Syntheses 1967, volume 9, page 136-142.]

FeBr₂ reacts with bromide and bromine to form the intensely colored, mixed-valence species [FeBr₃Br₉] ^-. [Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5]

References