Tellurium(IV) bromide (tellurium tetrabromide)

Structure and bonding

In the solid state TeBr4 does not exist simply as discrete tetrahedral units. Instead, it adopts structures in which bromide ligands bridge between tellurium centers, giving each tellurium a higher apparent coordination number and a distorted geometry. In vapor or solution at low concentration, species closer to monomeric TeBr4 may be present. The bonding is largely covalent with polar character, reflecting the metalloid nature of tellurium.

Preparation and typical reactions

TeBr4 is commonly prepared by the direct combination of tellurium and elemental bromine, or by halide exchange from other tellurium halides. It acts as a Lewis acid and can accept electron pairs from donors. It hydrolyzes in the presence of water to give hydrobromic acid and oxidized tellurium oxy-species, and it can be reduced to lower tellurium halides under suitable conditions.

Physical and chemical properties

The compound is a colored crystalline solid with appreciable sensitivity to moisture and to strong nucleophiles. It is soluble in some nonpolar and halogenated solvents where it can participate in halogenation or complexation reactions. Chemical behavior includes acting as a brominating agent, engaging in ligand exchange, and forming adducts with Lewis bases.

Uses, examples and related compounds

TeBr4 is used as a precursor to other tellurium compounds and occasionally as a source of electrophilic bromine in synthesis. Related halides include tellurium(IV) chloride and tellurium(IV) iodide, which show analogous chemistry but differ in volatility and reactivity. For more detailed data and spectral information see the compound entries at reference A and reference B.

Safety and handling

Tellurium halides are corrosive and can release hydrobromic acid on contact with moisture; they should be handled under inert atmosphere in appropriate glassware. Tellurium compounds may be toxic and may impart a characteristic metallic or garlic-like odor to breath and sweat after exposure. Consult material safety resources and product data sheets before working with TeBr4: safety data and handling guidance.

• Key points: formula TeBr4; tellurium in +4 oxidation state; moisture sensitive.
• Related topics: tellurium chemistry, halide exchange, Lewis acid behavior.