Mercury(I) bromide or mercurous bromide is the
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
composed of
mercury and
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...
with the
formula Hg
2Br
2. It changes color from white to yellow when heated
and
fluoresces a salmon color when exposed to
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
light. It has applications in
acousto-optical devices.
[
]
A very rare mineral form is called kuzminite and has the chemical formula .
Reactions
Mercury(I) bromide is prepared by the oxidation of elemental mercury with elemental bromine or by adding
sodium bromide
Sodium bromide is an inorganic compound with the formula Na Br. It is a high-melting white, crystalline solid that resembles sodium chloride. It is a widely used source of the bromide ion and has many applications.Michael J. Dagani, Henry J. Ba ...
to a solution of
mercury(I) nitrate
Mercury(I) nitrate is a inorganic compound, a salt of mercury and nitric acid with the formula Hg2(NO3)2. A yellow solid, the compound is used as a precursor to other complexes of Hg22+ complexes.The structure of the hydrate has been determined b ...
.
It decomposes to
mercury(II) bromide
Mercury(II) bromide or mercuric bromide is an inorganic compound with the formula HgBr2. This white solid is a laboratory reagent. Like all mercury salts, it is highly toxic.
Preparation
Mercury(II) bromide can be produced by reaction of metalli ...
and elemental mercury.
Structure
In common with other Hg(I) (mercurous) compounds which contain linear X-Hg-Hg-X units, Hg
2Br
2 contains linear BrHg
2Br 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.
[Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications ] 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 Hg
22+ 2Br
−,
although it is actually a molecular compound.
References
{{bromine compounds
Mercury(I) compounds
Bromides
Metal halides