Mercury(I) iodide

Mercury(I) iodide
IUPAC name Mercury(I) iodide
Other names Mercurous iodide
Identifiers
CAS number	15385-57-6
Properties
Molecular formula	Hg2I2
Molar mass	654.98g mol-1
Appearance	yellow powder[1]
Density	7.7 g cm-3[2]
Melting point	140 ˚C (Sublimes)
Solubility in water	Slightly soluble in water, insoluble in alcohol
Hazards
R-phrases	R26/27/28, R33, R50/53
S-phrases	(S1/2), S13, S28, S45, S60, S61
Main hazards	Toxic, corrosive
Y iodide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Mercury(I) iodide is a chemical compound of mercury and iodine. The chemical formula is Hg₂I₂. It is photosensitive and decomposes easily to mercury and HgI₂.

Synthesis

Mercury(I) iodide can be prepared by direct combination of mercury and iodine:

2 Hg + I₂ → Hg₂I₂

Structure

In common with other Hg(I) (mercurous) compounds which contain linear X-Hg-Hg-X units, Hg₂I₂ contains linear IHg₂I units with an Hg-Hg bond length of 272 pm (Hg-Hg in the metal is 300 pm) and an Hg-I bond length of 268 pm.^[3] The overall coordination of each Hg atom is octahedral as it has in addition to the two nearest neighbours there are four other I atoms at 351 pm. ^[3]The compound is often formulated as Hg₂²⁺ 2I⁻.^[4]

Uses

Mercury(I) iodide, called Protiodide, was used as a medicine in early years. However, due to the high toxicity of the substance, it is no longer used.

See also

• Mercury(II) iodide, HgI₂

References

1. ^ MaTecK GmbH
2. ^ WebElements Periodic Table of the Elements
3. ^ ^{a b} Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
4. ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5