cobreII

Copper(II), or cobre(II) in some languages, refers to copper in the +2 oxidation state. In chemistry, Cu2+ is the most common oxidation state for copper in inorganic compounds. In aqueous solution, Cu2+ forms the octahedral hexaaquacopper(II) complex [Cu(H2O)6]2+, which is typically blue.

Common copper(II) salts include copper sulfate pentahydrate (CuSO4·5H2O), copper chloride (CuCl2), copper nitrate (Cu(NO3)2, and copper acetate (Cu(OAc)2). Solid Cu(OH)2 is a light blue precipitate, while CuO is a black solid. Copper(II) centers exhibit various coordination numbers, typically 4, 5, or 6, with geometries such as square planar, square pyramidal, or distorted octahedral. Jahn-Teller distortion is common in octahedral Cu(II) complexes, often elongating axial bonds.

Occurrence and production: copper minerals include malachite (Cu2CO3(OH)2) and azurite, while tenorite is CuO. Copper is refined from copper ores through smelting and refining; oxidized zones can yield salts like chalcanthite (CuSO4·5H2O).

Reactions: Cu2+ can be reduced to Cu+ or to metallic copper under suitable conditions. It forms complexes with ligands such as ammonia, giving deep blue solutions like [Cu(NH3)4]2+. In basic solution, Cu2+ hydrolyzes to form Cu(OH)2 and can convert to oxide species upon heating or aging.

Biological role and safety: copper is an essential trace element in many organisms, but copper(II) salts are toxic at higher concentrations and can irritate skin and mucous membranes; they may stain fabrics and skin blue or green.