Copper(II) selenide is an inorganic binary compound between copper and selenium, with the chemical formula CuSe.
Properties Copper(II) selenide is soluble in hydrochloric acid and sulfuric acid, evolving hydrogen selenide and sulfur dioxide respectively. It is oxidized to copper(II) selenite by nitric acid.
Occurrence Copper selenides are the most common selenium minerals. CuSe is known in mineralogy as klockmannite.
Structure Copper(II) selenide exhibits polymorphism. α-CuSe (klockmannite) is generally regarded as having a similar structure to CuS (covellite), but the precise structure could not be determined from powder diffraction data. γ-CuSe is stable above and is also hexagonal with similar unit cell dimensions (a = 3.984 Å, c = 17.288 Å at ). The diffraction pattern is very similar to that of α-CuSe.
Uses Copper(II) selenide is produced in situ to form a protective black coating on iron or steel parts in some cold-bluing processes. Bluing solutions that operate in this manner will typically be labeled as containing selenous acid or selenium dioxide. It has also been investigated for use in the treatment of colon cancer.
Related compounds Other copper selenides have been characterized including Cu1.8Se (non-stoichiometric), Cu3Se2, CuSe2 (low pressure modification), and CuSe2II (high pressure modification). A copper iron selenide (CuFeSe2) has also been characterized.
References