CadmiumII

Cadmium(II) refers to the divalent cadmium cation, Cd2+, which is the most common oxidation state for cadmium in inorganic compounds. In aqueous solution Cd2+ forms hydrated species, typically six-coordinate [Cd(H2O)6]2+, and it readily forms complexes with a range of ligands, including halides, sulfide, cyanide, and amines.

Cadmium is relatively rare in the Earth's crust and occurs mainly as a byproduct of zinc and lead ore processing. Important cadmium-containing minerals include greenockite (CdS) and otavite (CdCO3). In chemical form, cadmium(II) appears in a variety of salts and compounds, such as cadmium chloride (CdCl2), cadmium sulfate (CdSO4), cadmium carbonate (CdCO3), and cadmium sulfide (CdS). Cadmium(II) salts exhibit diverse solubility and coordination behavior depending on the anions and ligands involved.

Applications and occurrence in materials derive from its chemistry. Historically, cadmium(II) compounds have been used in nickel–cadmium batteries and as pigments, notably cadmium sulfide in yellow pigments. Cadmium-containing materials continue to appear in certain photoelectric, electronic, and optoelectronic contexts, though many uses have declined or become tightly regulated due to safety concerns.

Health and environmental aspects are central to the cadmium(II) ion. Cadmium compounds are highly toxic to humans and animals; exposure, especially via inhalation or ingestion, can cause kidney damage, bone effects, and other health problems. Cadmium is persistent in the environment and can accumulate in living organisms. Consequently, cadmium and its compounds are subject to strict regulatory controls to limit emissions, exposure, and ecological impact.