- Silver cyanide is an inorganic compound with the formula AgCN, composed of silver(I) ions bound to the cyanide anion. It typically appears as a white to grayish crystalline powder and is notable for being highly insoluble in water. This very low solubility arises from the strong linear Ag–C≡N coordination, which forms a tightly bonded, chain-like polymeric structure. Despite its low solubility, silver cyanide can dissolve in excess cyanide due to the formation of stable argentocyanide complexes, a property central to its industrial relevance.
- The compound is best known for its role in silver electroplating, where it serves as a key component of cyanide-based plating baths. In these systems, complex ions such as [Ag(CN)₂]⁻ provide a controlled and stable source of silver ions, allowing for uniform deposition on metal surfaces. This method produces smooth, adherent, and high-purity silver coatings used in electronics, jewelry, electrical contacts, and decorative finishes. The predictable electrochemical behavior of cyanide complexes makes them uniquely suited for such precision plating processes.
- Chemically, silver cyanide is sensitive to light and can slowly darken as metallic silver forms. However, the most important aspect of the compound is cyanide toxicity. The cyanide ion binds strongly to iron in cellular enzymes, interfering with respiration, meaning that silver cyanide—like all cyanide compounds—must be handled with stringent safety precautions. Industrial use is therefore highly regulated, with measures to control storage, waste treatment, and worker exposure. Acid exposure is particularly dangerous because cyanide can release hydrogen cyanide gas, a highly hazardous substance.
- In applications beyond plating, silver cyanide has been used in certain analytical chemistry methods, especially gravimetric determinations involving silver, due to its very low solubility product. Research settings occasionally explore its structural, spectroscopic, or coordination chemistry features, especially its polymeric chains and the behavior of argentocyanide complexes. While scientifically interesting, its practical uses remain concentrated in controlled industrial environments due to the risks associated with cyanide handling.
