Vanadium tetrachloride

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Vanadium tetrachloride
Structural formula of the vanadium tetrachloride molecule
3D model of the vanadium tetrachloride molecule
Names
IUPAC names
Vanadium tetrachloride
Vanadium(IV) chloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.692 Edit this at Wikidata
EC Number
  • 231-561-1
RTECS number
  • YW2625000
UNII
  • InChI=1S/4ClH.2V/h4*1H;;/q;;;;2*+2/p-4 checkY
    Key: UNUHYFVFMNJHJW-UHFFFAOYSA-J checkY
  • InChI=1/4ClH.2V/h4*1H;;/q;;;;2*+2/p-4
    Key: UNUHYFVFMNJHJW-XBHQNQODAR
  • Cl[V](Cl)(Cl)Cl
Properties
VCl4
Molar mass 192.75 g/mol
Appearance bright red liquid, moisture sensitive
Odor pungent
Density 1.816 g/cm3, liquid
Melting point −24.5 °C (−12.1 °F; 248.7 K)
Boiling point 148 °C (298 °F; 421 K)
decomposes
Solubility soluble in CH2Cl2
Vapor pressure 7.9 Pa
+1130.0·10−6 cm3/mol
Structure
tetrahedral
Dipole moment
 0 D
Hazards
Main hazards toxic; oxidizer; hydrolyzes to release HCl
NFPA 704 (fire diamond)
3
0
2
W
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 160 mg/kg (rat, oral)
Related compounds
Other anions
 vanadium tetrafluoride, ,
Other cations
 titanium tetrachloride, , niobium tetrachloride,
Related compounds
 vanadium trichloride
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

Vanadium tetrachloride is the inorganic compound with the formula VCl4. This bright red liquid serves as a useful reagent for the preparation of other vanadium compounds.

Synthesis, bonding, basic properties[]

With one more valence electron than diamagnetic TiCl4, VCl4 is a paramagnetic liquid. It is one of only a few paramagnetic compounds that is liquid at room temperature.

VCl4 is prepared by chlorination of vanadium metal. VCl5 does not form in this reaction; Cl2 lacks the oxidizing power to attack VCl4. VCl5 can however be prepared indirectly from VF5 at −78 °C.[1] In contrast, the heavier analogues NbCl5 and TaCl5 are stable and not particularly oxidizing. VF5 can be prepared directly by fluorination of vanadium metal, reflecting the increased oxidizing power of F2 vs Cl2. Indicative of its oxidizing power, VCl4 releases Cl2 at its boiling point (standard pressure) to afford VCl3.

Reactions[]

Consistent with its high oxidizing power, VCl4 reacts with HBr at -50 °C to produce VBr3. The reaction proceeds via VBr4, which releases Br2 during warming to room temperature.[2]

2 VCl4 + 8 HBr → 2 VBr3 + 8 HCl + Br2

VCl4 forms adducts with many donor ligands, for example, VCl4(THF)2.

It is the precursor to vanadocene dichloride.

Organic chemistry[]

In organic synthesis, VCl4 is used for the oxidative coupling of phenols. For example, it converts phenol into a mixture of 4,4'-, 2,4'-, and 2,2'-biphenols:[3]

2 C6H5OH + 2 VCl4 → HOC6H4–C6H4OH + 2 VCl3 + 2 HCl

Applications[]

VCl4 is a catalyst for the polymerization of alkenes, especially those useful in the rubber industry. The underlying technology is related to Ziegler–Natta catalysis, which involves the intermediacy of vanadium alkyls.

Safety considerations[]

VCl4 is a volatile, aggressive oxidant that readily hydrolyzes to release HCl.

References[]

  1. ^ Tamadon, Farhad; Seppelt, Konrad (2013). "The Elusive Halides VCl5, MoCl6, and ReCl6". Angew. Chem. Int. Ed. 52 (2): 767–769. doi:10.1002/anie.201207552. PMID 23172658.
  2. ^ Calderazzo, F.; Maichle-Mössmer, C.; G., Pampaloni; J., Strähle (1993). "Low-temperature Syntheses of Vanadium(III) and Molybdenum(IV) Bromides by Halide Exchange". Dalton Transactions (5): 655–8. doi:10.1039/DT9930000655.
  3. ^ O’Brien, M. K.; Vanasse, B. (2004). "Vanadium(IV) Chloride". In Paquette, L. (ed.). Encyclopedia of Reagents for Organic Synthesis. New York, NY: J. Wiley & Sons. doi:10.1002/047084289X.rv001. ISBN 0471936235.
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