mercuric

Mercuric is an adjective used in inorganic chemistry to describe compounds of the element mercury in the +2 oxidation state, denoted Hg2+. It contrasts with mercurous compounds, which contain mercury in the +1 oxidation state (Hg2^2+). In common IUPAC usage, mercuric indicates Hg(II) species, whereas mercurous refers to Hg(I).

Mercuric compounds cover a wide range of chemical classes, including halides, oxides, sulfates, nitrates, and organomercury derivatives. Many mercuric salts are soluble in water to varying degrees and can act as oxidizing agents. The mercuric ion is typically described as Hg2+ in aqueous chemistry, and it forms complexes with ligands such as sulfide, chloride, cyanide, and various organic donors. Mercuric sulfide (HgS) occurs naturally as cinnabar and is used historically as a pigment; mercuric oxide (HgO) and mercuric chloride (HgCl2) are among well-known mercuric compounds. The chemistry of mercuric species often involves strong bonding with sulfur-containing ligands.

Toxicity and safety considerations are central to mercuric chemistry. Mercuric compounds are generally highly toxic and can bioaccumulate, presenting risks through inhalation, ingestion, or dermal exposure. As a result, many mercuric reagents are subject to strict regulatory control and guidelines for safe handling, disposal, and environmental protection. Their use has diminished in medicine and consumer products due to safety concerns, though mercuric salts still appear in some industrial applications and scientific research under appropriate controls.

Common examples include mercuric chloride (HgCl2), mercuric oxide (HgO), mercuric sulfate (HgSO4), mercuric nitrate (Hg(NO3)2), and mercuric sulfide (HgS, cinnabar). The term mercuric thus denotes mercury in the +2 oxidation state across a variety of compounds and contexts.