Tetraiodomercurate(II) is an inorganic dianion that is found in potassium tetraiodomercurate(II), as well as various other salts. Tetraiodomercurate(II) has the chemical formula . The central mercury atom in this coordination complex has a +2 oxidation state. Although the complex has tetrahedral molecular geometry, its exact geometry can be influenced by hydrogen bonding to the iodine atoms.
Salts At room temperature, salts of tetraiodomercurate(II) come in various colors ranging from red to light yellow.
Silver tetraiodomercurate(II) and copper tetraiodomercurate(II), and respectively, can be generated from the precursor potassium tetraiodomercurate(II) and are thermochromic. Its indium, gold, thallium, rubidium, cesium, and lithium salts are not thermochromic.
The aqueous solution of its barium salt, (BaHgI4), is known as Rohrbach's solution and has historically been used as a heavy liquid.
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