Vanadium(III) bromide

Vanadium(III) bromide
Vanadium(III) bromide
Names
IUPAC name
Vanadium(III) bromide
Other names
Vanadium tribromide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.382 Edit this at Wikidata
EC Number
  • 236-736-6
RTECS number
  • YW2750000
  • InChI=1S/3BrH.V/h3*1H;/q;;;+3/p-3 checkY
    Key: ZOYIPGHJSALYPY-UHFFFAOYSA-K checkY
  • InChI=1/3BrH.V/h3*1H;/q;;;+3/p-3
    Key: ZOYIPGHJSALYPY-DFZHHIFOAP
  • Br[V](Br)Br
Properties
VBr3
Molar mass 290.654 g/mol
Appearance Green-black solid
Density 4 g/cm3
soluble
Solubility soluble in THF
(forms adduct)
+2890.0·10−6 cm3/mol
Structure
octahedral
Related compounds
Other anions
 Vanadium(III) chloride
Other cations
 Titanium(III) bromide
Molybdenum(III) bromide
Related compounds
 Vanadium(II) bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Vanadium(III) bromide, also known as vanadium tribromide, describes the inorganic compounds with the formula VBr3 and its hydrates. The anhydrous material is a green-black solid. In terms of its structure, the compound is polymeric with octahedral vanadium(III) surrounded by six bromide ligands.

Preparation

VBr3 has been prepared by treatment of vanadium tetrachloride with hydrogen bromide:

2 VCl4 + 8 HBr → 2 VBr3 + 8 HCl + Br2

The reaction proceeds via the unstable vanadium(IV) bromide (VBr4), which releases Br2 near room temperature.[1]

It is also possible to prepare vanadium(III) bromide by reacting bromine with vanadium or ferrovanadine:[2]

2 V + 3 Br2 → 2 VBr3
2 VFe + 6 Br2 → 2 VBr3 + FeBr3

Properties

Physical

Vanadium(III) bromide is present in the form of black, leafy, very hygroscopic crystals with a sometimes greenish sheen. It is soluble in water with green color. Its crystal structure is isotypic to that of vanadium(III) chloride with space group R3c (space group no. 167), a = 6.400 Å, c = 18.53 Å. When heated to temperatures of around 500 °C, a violet gas phase is formed, from which, under suitable conditions, red vanadium(IV) bromide can be separated by rapid cooling, which decomposes at −23 °C.[2]

Chemical

Like vanadium(III) chloride, vanadium(III) bromide forms red-brown soluble complexes with dimethoxyethane and THF, such as mer-VBr3(THF)3.[3]

Aqueous solutions prepared from VBr3 contain the cation trans-[VBr2(H2O)4]+. Evaporation of these solutions give the salt trans-[VBr2(H2O)4]Br.(H2O)2.[4]

Further reading

  • Stebler, A.; Leuenberger, B.; Guedel, H. U. "Synthesis and crystal growth of A3M2X9 (A = Cs, Rb; M = Ti, V, Cr; X = Cl, Br)" Inorganic Syntheses (1989), volume 26, pages 377–85.

References

  1. ^ Calderazzo, Fausto; Maichle-Mössmer, Cäcilie; Pampaloni, Guido; Strähle, Joachim (1993). "Low-Temperature Syntheses of Vanadium(III) and Molybdenum(IV) Bromides by Halide Exchange". J. Chem. Soc., Dalton Trans. (5): 655–658. doi:10.1039/DT9930000655.
  2. ^ a b Brauer, Georg (1981). Handbuch der präparativen anorganischen Chemie. Vol. 3 (3., umgearb. ed.). Stuttgart: Enke. ISBN 978-3-432-87823-2.
  3. ^ G. W. A. Fowles, G. W. A.; Greene, P. T.; Lester, T. E. "Ether Complexes of Tervalent Titanium and Vanadium" J. Inorg, Nucl. Chem., 1967. Vol. 29. pp. 2365 to 2370.
  4. ^ Donovan, William F.; Smith, Peter W. (1975). "Crystal and Molecular Structures of Aquahalogenovanadium(III) Complexes. Part I. X-Ray Crystal Structure of trans-Tetrakisaquadibromo-Vanadium(III) Bromide Dihydrate and the Isomorphous Chloro- Compound". Journal of the Chemical Society, Dalton Transactions (10): 894. doi:10.1039/DT9750000894.