Tellurium tetrachloride is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the

empirical formula In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, is simply SO, as is the empir ...

TeCl₄. The compound is volatile, subliming at 200 °C at 0.1 mmHg. Molten TeCl₄ is ionic, dissociating into TeCl₃⁺ and Te₂Cl₁₀²⁻.

Structure

TeCl₄ is monomeric in the gas phase, with a structure similar to that of SF₄. In the solid state, it is a

tetramer A tetramer () (''tetra-'', "four" + '' -mer'', "parts") is an oligomer formed from four monomers or subunits. The associated property is called ''tetramery''. An example from inorganic chemistry is titanium methoxide with the empirical formula ...

cubane-type cluster A cubane-type cluster is an arrangement of atoms in a molecular structure that forms a cube. In the simplest case, the eight vertices are symmetry equivalent and the species has Oh symmetry group, symmetry. Such structure occurs in the hydrocarbon ...

, consisting of a Te₄Cl₄ core and three terminal chloride ligands for each Te. Alternatively, this tetrameric structure can be considered as a Te₄ tetrahedron with face-capping chlorines and three terminal chlorines per tellurium atom, giving each tellurium atom a distorted octahedral environment

Synthesis

TeCl₄ is prepared by chlorination of

tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...

powder: :Te + 2 Cl₂ → TeCl₄ The reaction is initiated with heat. The product is isolated by distillation. Crude TeCl₄ can be purified by distillation under an atmosphere of chlorine. Alternatively TeCl₄ can be prepared using sulfuryl chloride (SO₂Cl₂) as a chlorine source. Yet another method involves the reaction of tellurium with

sulfur monochloride Disulfur dichloride (or disulphur dichloride by the British English spelling) is the inorganic compound of sulfur and chlorine with the formula . It is an amber oily liquid. Sometimes, this compound is incorrectly named ''sulfur monochloride'' (o ...

(S₂Cl₂) at room temperature. This exothermic reaction rapidly forms white needle-like crystals of TeCl₄.

Reactions

Tellurium tetrachloride is the gateway compound for high valent

organotellurium compound Organotellurium chemistry describes the synthesis and properties of organotellurium compounds, chemical compounds containing a carbon-tellurium chemical bond. Organotellurium chemistry is a lightly studied area, in part because of it having few appl ...

s. Arylation gives, depending on conditions, . TeCl₄ has few applications in organic synthesis. Its equivalent weight is high, and the toxicity of organotellurium compounds is problematic. Possible applications of tellurium tetrachloride to

organic synthesis Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...

have been reported. and It adds to alkenes to give Cl-C-C-TeCl₃ derivatives, wherein the Te can be subsequently removed with sodium sulfide. Electron-rich arenes react to give aryl Te compounds. Thus,

anisole Anisole, or methoxybenzene, is an organic compound with the formula . It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is mainly ...

gives TeCl₂(C₆H₄OMe)₂, which can be reduced to the diaryl telluride. TeCl₄ is a precursor to tellurium-containing

heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

s like

tellurophene Tellurophene is the organotellurium compound with the formula . It is a heavy analogue of thiophene and selenophene. The compound is a pale yellow liquid. A number of substituted tellurophenes are known. Synthesis In 1966, Mack report a synthe ...

s. Heating a mixture of TeCl₄ and metallic tellurium gives

tellurium dichloride Tellurium dichloride is a chloride of tellurium with the chemical formula TeCl2. Preparation Tellurium dichloride can be produced by reacting tellurium with difluorodichloromethane. It can also be produced by the comproportionation of telluri ...

(TeCl₂). In moist air, TeCl₄ forms tellurium oxychloride (TeOCl₂), which further decomposes with excess water to form

tellurous acid Tellurous acid is an inorganic compound with the chemical formula, formula H2TeO3. It is the oxoacid of tellurium(IV). This compound is not well characterized. An alternative way of writing its formula is (HO)2TeO. In principle, tellurous acid ...

(H₂TeO₃).

Safety considerations

As is the case for other tellurium compounds, TeCl₄ is toxic. It also releases HCl upon hydrolysis.

References

{{Chlorides Tellurium(IV) compounds Chlorides Tellurium halides Deliquescent materials Chalcohalides