Mercury(I) bromide

Mercury(I) bromide

Mercury(I) bromide
Names
IUPAC name Mercury(I) bromide
Other names Mercurous bromide
Identifiers
CAS Number	15385-58-7 Y
PubChem	24829
Properties
Chemical formula	Hg2Br2
Molar mass	560.99 g/mol
Appearance	white to yellow tetragonal crystals
Odor	odorless
Density	7.307 g/cm3, solid
Melting point	405 °C (761 °F; 678 K)
Boiling point	~ 390 °C (734 °F; 663 K) sublimes
Solubility in water	3.9 x 10−5 g/100 mL
Solubility	insoluble in ether, acetone, alcohol
Structure
Molecular shape	linear
Vapor pressure	{{{value}}}
Related compounds
Other anions	Mercury(I) fluoride Mercury(I) chloride Mercury(I) iodide
Other cations	Zinc bromide Cadmium bromide Mercury(II) bromide
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

Mercury(I) bromide or mercurous bromide is the chemical compound composed of mercury and bromine with the formula Hg₂Br₂. It changes color from white to yellow when heated and fluoresces a salmon color when exposed to ultraviolet light. It has applications in acousto-optical devices.

A very rare mineral form is called kuzminite, Hg₂(Br,Cl)₂.

Reactions

Mercury(I) bromide is prepared by the oxidation of elemental mercury with elemental bromine or by adding sodium bromide to a solution of mercury(I) nitrate. It decomposes to mercury(II) bromide and elemental mercury.

Structure

In common with other Hg(I) (mercurous) compounds which contain linear X-Hg-Hg-X units, Hg₂Br₂ contains linear BrHg₂Br units with an Hg-Hg bond length of 249 pm (Hg-Hg in the metal is 300 pm) and an Hg-Br bond length of 271 pm. The overall coordination of each Hg atom is octahedral as, in addition to the two nearest neighbours, there are four other Br atoms at 332 pm. The compound is often formulated as Hg₂²⁺ 2Br⁻, although it is actually a molecular compound.