Mercury(I) iodide
Encyclopedia
Mercury iodide is a chemical compound
of mercury
and iodine
. The chemical formula is Hg2I2. It is photosensitive and decomposes easily to mercury and HgI2.
and iodine
:
2 Hg + I2 → Hg2I2
, was used as a medicine in early years. However, due to the high toxicity of the substance, it is no longer used.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
of mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
and iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
. 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 mercuryMercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
and iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
:
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. 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. The compound is often formulated as Hg22+ 2I−.Uses
Mercury(I) iodide, called ProtiodideProtiodide
Protiodide is an iodide of mercury and was a very commonly used drug in the 19th century, prescribed for everything from acne to kidney disease. It was also the treatment of choice for syphilis...
, was used as a medicine in early years. However, due to the high toxicity of the substance, it is no longer used.