Copper monosulfide

A black colloidal precipitate of copper monosulfide is formed when hydrogen sulfide, , is bubbled through solutions of Cu(II) salts. This is the basis of its industrial production. Special forms of CuS for certain applications can be prepared by melting an excess of sulfur with copper(I) sulfide or by precipitation with hydrogen sulfide from a solution of anhydrous copper(II) chloride in anhydrous ethanol. Nanoparticles of CuS can be prepare by reaction of dissolved copper(II) chloride with thioglycolic acid. The reaction of copper with molten sulfur followed by boiling sodium hydroxide and the reaction of sodium sulfide with aqueous copper sulfate will also produce copper sulfide. ==CuS structure and bonding==

Copper sulfide crystallizes in the hexagonal crystal system, and this is the form of the mineral covellite. There is also an amorphous high pressure form as a Cu(II) compound would have a d9 configuration and be expected to be paramagnetic. indicate that all of the copper atoms have an oxidation state of +1. This contradicts a formulation based on the crystal structure and obeying the octet rule that is found in many textbooks (e.g.) describing CuS as containing both {{chem2|Cu^{I} }} and {{chem2|Cu^{II} }} i.e. . An alternative formulation as was proposed and supported by calculations. The formulation should not be interpreted as containing radical anion, but rather that there is a delocalized valence "hole".{{cite journal Electron paramagnetic resonance studies on the precipitation of Cu(II) salts indicates that the reduction of Cu(II) to Cu(I) occurs in solution.{{cite journal ==See also==