Organocopper compounds in organometallic chemistry contain carbon to copper chemical bonds. Organocopper chemistry is the science of organocopper compounds describing their physical properties, synthesis and reactions. They are reagents in organic chemistry.
The first organocopper compound, the explosive copper(I) acetylide Cu2C2 (Cu-C≡C-Cu), was synthesized by Rudolf Christian Böttger in 1859 by passing acetylene gas through copper(I) chloride solution:
Organocopper compounds are diverse in structure and reactivity, but organocopper compounds are largely limited in oxidation states to copper(I), sometimes denoted Cu+1. As a d10 metal center, it is related to Ni(0), but owing to its higher oxidation state, it engages in less pi-backbonding. Organic derivatives of Cu(II) and Cu(III) are invoked as intermediates but rarely isolated or even observed. In terms of geometry, copper(I) adopts symmetrical structures, in keeping with its spherical electronic shell. Typically one of three coordination geometries is adopted: linear 2-coordinate, trigonal 3-coordinate, and tetrahedral 4-coordinate. Organocopper compounds form complexes with a variety of soft ligands such as alkylphosphines (R3P), thioethers (R2S), and cyanide (CN−).
Copper(I) salts have long been known to bind CO, albeit weakly. A representative complex is CuCl(CO), which is polymeric. In contrast to classical metal carbonyls, pi-backbonding is not strong in these compounds.
Alkenes bind to copper(I), although again generally weakly. The binding of ethylene to Cu in proteins is of broad significance in plant biology so much so that ethylene is classified as a plant hormone. Its presence, detected by the Cu-protein, affects ripening and many other developments.
Although copper does not form a metallocene, half-sandwich complexes can be produced. One such derivative is (η-cyclopentadienyl triethylphosphine) copper. This compound is a relatively rare example of an organocopper complex that follows the 18-electron rule.