MercuryII

Mercury(II) refers to chemical species in which mercury is in the +2 oxidation state. The mercuric ion, Hg^2+, is the common representative. The ion is d10 and in aqueous solution is typically highly hydrated, often described as [Hg(H2O)6]^2+. Mercury(II) forms a wide range of salts and coordination compounds, with properties that reflect its soft Lewis-acid character and tendency to bind ligands such as chloride, water, ammonia, cyanide, and sulfide.

Common examples include mercury(II) chloride (HgCl2), a white crystalline solid that is moderately soluble in water and undergoes hydrolysis to basic chlorides upon dissolution. In solution, Hg^2+ forms several complexes; for instance, reaction with ammonia yields the diamminemercury(II) complex, [Hg(NH3)2]Cl2. The chemistry of Hg^2+ includes numerous other coordination compounds with various ligands, illustrating its versatility as a center for complex formation.

Occurrence and production: Mercury occurs in nature chiefly as minerals such as cinnabar, the sulfide HgS, which is the principal ore. Mercury metal is produced by roasting cinnabar to obtain oxide and then reducing it. In aqueous and solid-state chemistry, Hg^2+ species are encountered in a variety of inorganic salts and complexes.

Safety and environmental aspects: Mercury(II) compounds are highly toxic to humans and wildlife, with exposure capable of affecting the nervous, renal, and immune systems. In the environment, inorganic mercury can be transformed and bioaccumulated into more harmful organomercury species. Due to toxicity, handling and use of mercury(II) compounds are subject to stringent safety measures and regulatory controls.