Vanadium tetrachloride is the inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula V

Vanadium

Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...

Cl₄. This bright red liquid is a useful reagent

Reagent

A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...

 for the preparation of other vanadium compounds.

Synthesis, bonding, basic properties

With one more valence electron than diamagnetic TiCl₄

Titanium tetrachloride

Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is an unusual example of a metal halide that is highly volatile...

, 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; Cl₂ lacks the oxidizing power to attack VCl₄. In contrast, the heavier analogues NbCl₅

Niobium(V) chloride

Niobium chloride, also known as niobium pentachloride, is a yellow crystalline solid. It hydrolyzes in air, and samples are often contaminated with small amounts of NbOCl3. It is often used as a precursor to other compounds of niobium...

 and TaCl₅

Tantalum(V) chloride

Tantalum chloride, also known as tantalum pentachloride, is the inorganic compound with the formula TaCl5. This white powder is a starting material in tantalum chemistry. It hydrolyzes readily, releasing HCl. TaCl5 is prepared by heating tantalum metal in chlorine...

 are stable and not particularly oxidizing. Of course, VF₅ does exist, reflecting the increased oxidizing power of F₂

Fluorine

Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

 vs Cl₂

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

. Indicative of its oxidizing power, VCl₄ releases Cl₂ at its boiling point (standard pressure) to afford vanadium(III) chloride

Vanadium(III) chloride

Vanadium trichloride is the inorganic compound with the formula VCl3. This purple salt is a common precursor to other vanadium complexes.-Structure:...

.

Reactions

Consistent with its high oxidizing power, VCl₄ reacts with HBr at -50 °C to produce VBr₃

Vanadium(III) bromide

Vanadium bromide, also known as vanadium tribromide, is VBr3. In the solid-state, this species is a polymeric with octahedral vanadium surrounded by six bromide ligands....

. The reaction proceeds via VBr₄, which releases Br₂ during warming to room temperature.

2 VCl₄ + 8 HBr → 2 VBr₃ + 8 HCl + Br₂

VCl₄ forms adduct

Adduct

An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...

s with many donor ligands, for example, VCl₄(THF

ThF

Follicular B helper T cells , are antigen-experienced CD4+ T cells found in the B cell follicles of secondary lymphoid organs such as lymph nodes, spleens and Peyer's patches, and are identified by their constitutive expression of the B cell follicle homing receptor CXCR5...

)₂.

It is the precursor to vanadocene dichloride

Vanadocene dichloride

Vanadocene dichloride, dichloro bisvanadium is 2VCl2 . It is a structural analoque of titanocene dichloride but with vanadium instead of titanium....

.

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.

Organic chemistry

In organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, VCl₄ is used to couple phenols. For example, it converts phenol

Phenol

Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

 into 4,4'-biphenol. It is reduced to

Vanadium(III) chloride

Vanadium trichloride is the inorganic compound with the formula VCl3. This purple salt is a common precursor to other vanadium complexes.-Structure:...

 in the process.

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

This reaction highlights the oxidizing ability of VCl₄, consistent with it being resistant to further oxidation by Cl₂.

Safety considerations

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

HCL

HCL or HCl can stand for:* Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia* Hardware compatibility list...

.