Copper(I) chloride (7758-89-6)

?Copper(I) Chloride (CAS NO.7758-89-6) commonly called cuprous chloride, is the lower chloride of copper, with the formula CuCl. This colorless solid is a versatile precursor to other copper compounds, including some of commercial significance. It occurs naturally as the rare mineral nantokite. Unlike other first-row transition metal halides, it forms stable complexes with carbon monoxide. It crystallizes in a diamondoid motif, reflecting the tendency of copper(I) to form tetrahedral complexes.
Although CuCl is insoluble in water, it dissolves in aqueous solutions containing suitable donor molecules. It forms complexes with halide ions, for example forming H₃O+ CuCl₂- with concentrated hydrochloric acid. It also dissolves in solutions containing CN-, S₂O₃₂-, and NH₃ to give complexes.
Solutions of CuCl in HCl or NH₃ absorb carbon monoxide to form colourless complexes such as the chloride-bridged dimer [CuCl(CO)]₂. The same hydrochloric acid solutions also react with acetylene gas to form [CuCl(C₂H₂)]. Ammoniacal solutions of CuCl react with acetylenes to form the explosive copper(I) acetylide. Complexes of CuCl with alkenes can be prepared by reduction of CuCl₂ by sulfur dioxide in the presence of the alkene in alcohol solution. Complexes with dienes such as 1,5-cyclooctadiene are particularly stable:

Copper and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.