Applied in a widely useful, thiosulfate-assisted, synthesis of a variety of diamine-CuCN complexes. Also used, commonly used as a polymerization catalyst. The compound is useful in organic synthesis, as a catalyst, reagent in the preparation of nitriles (sandmeyer reaction). It is also used in electroplating copper and iron, silver plating, brass plating, and copper-tin alloy plating. It is used to make phthalocyanine dyes and pigments. Used as insecticide, fungicide; as antifouling agent in marine paints.