Vanadium(III) bromide

Vanadium(III) bromide
Names
	IUPAC name Vanadium(III) bromide
	Other names Vanadium tribromide
Identifiers
CAS Number	13470-26-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	11476059 ;
ECHA InfoCard	100.033.382
EC Number	236-736-6;
PubChem CID	83509;
RTECS number	YW2750000;
CompTox Dashboard (EPA)	DTXSID4065498 ;
	InChI InChI=1S/3BrH.V/h31H;/q;;;+3/p-3 Key: ZOYIPGHJSALYPY-UHFFFAOYSA-K ; InChI=1/3BrH.V/h31H;/q;;;+3/p-3 Key: ZOYIPGHJSALYPY-DFZHHIFOAP;
	SMILES Br[V](Br)Br;
Properties
Chemical formula	VBr3
Molar mass	290.654 g/mol
Appearance	Green-black solid
Density	4 g/cm3
Solubility in water	soluble
Solubility	soluble in THF; (forms adduct)
Magnetic susceptibility (χ)	+2890.0·10−6 cm3/mol
Structure
Coordination geometry	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). verify (what is ?) Infobox references

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]

References

^ 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.
^ ^a ^b Brauer, Georg (1975). Handbuch der präparativen anorganischen Chemie Volume 3 (in German). the University of Michigan: Enke. p. 1409. ISBN 978-3-432-87823-2.
^ 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.
^ 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.

[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.

[Brauer-2] Brauer, Georg (1975). Handbuch der präparativen anorganischen Chemie Volume 3 (in German). the University of Michigan: Enke. p. 1409. 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.

[VX3aq6-4] 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.

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