Lead(II) bromide is the inorganic compound with the formula PbBr₂. It is a white powder. It is produced in the burning of typical leaded gasolines.Michael J. Dagani, Henry J. Barda, Theodore J. Benya, David C. Sanders "Bromine Compounds" in Ullmann's Encyclopedia of Industrial Chemistry" Wiley-VCH, Weinheim, 2000.

Preparation and properties

It is typically prepared from treating solutions of lead salts (e.g., (

lead(II) nitrate Lead(II) nitrate is an inorganic compound with the chemical formula Pb( NO3)2. It commonly occurs as a colourless crystal or white powder and, unlike most other lead(II) salts, is soluble in water. Known since the Middle Ages by the name plumbu ...

) with bromide salts. This process exploits its low solubility in water - only 0.455 g dissolves in 100 g of water at 0 °C. It is about ten times more soluble in boiling water. PbBr₂ has the same

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns ...

as lead chloride (

cotunnite Cotunnite is the natural mineral form of lead(II) chloride with formula PbCl2. It was first described in 1825 from an occurrence on Mount Vesuvius, Naples Province, Campania, Italy. It was named for Domenico Cotugno (Cotunnius) (1736–1822), Ita ...

) – they are

isomorphous In mathematics, an isomorphism is a structure-preserving mapping between two structures of the same type that can be reversed by an inverse mapping. Two mathematical structures are isomorphic if an isomorphism exists between them. The word is ...

. In this structure, Pb²⁺ is surrounded by nine Br⁻ ions in a distorted tricapped trigonal prismatic geometry. Seven of the Pb-Br distances are shorter, in the range 2.9-3.3 Å, while two of them are longer at 3.9 Å. The coordination is therefore sometimes described as (7+2). Lead bromide was prevalent in the environment as the result of the use of leaded gasoline.

Tetraethyl lead Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb( C2H5)4. It is a fuel additive, first being mixed with gasoline beginning in the 1920s as a patented octane rating booster that al ...

was once widely used to improve the combustion properties of gasoline. To prevent the resulting lead oxides from fouling the engine, gasoline was treated with an

organobromine compound Organobromine compounds, also called organobromides, are organic compounds that contain carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons avai ...

that converted lead oxides into the more volatile lead bromide, which was then exhausted from the engine into the environment.

Safety

Like other compounds containing lead, lead(II) bromide is categorized as ''probably carcinogenic to humans'' (Category 2A), by the

International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...

(IARC). Its release into the environment as a product of leaded gasoline was highly controversial.

References

Lead(II) compounds Bromides Metal halides {{inorganic-compound-stub