Cuprate

Oxide cuprates

Many stable or metastable alkali metal cuprates(III) are known, all salts of the polyanion . They are strong oxidants, oxidizing water. They are typically produced through extremely large oxygen activities. Alkali metals larger than sodium produce dark-blue salts, but sodium cuprate(III) is red-brown.

One of the simplest oxide-based cuprates is potassium cuprate(III) . Even so, is a non-stoichiometric compound, so the more exact formula is and x is very close to 2. This causes the formation of defects in the crystal structure, and this leads to the tendency of this compound to be reduced.

One of the most studied inorganic cuprates is , also known as YBCO. This oxide cuprate has been the subject of extensive research due to its ability to conduct electricity without resistance at relatively high temperatures. It is the parent of a family of cuprate superconductors.

Coordination complexes

Copper forms many anionic coordination complexes with negatively charged ligands such as cyanide, hydroxide, and halides, as well as alkyls and aryls (see ).

Copper(I)

Cuprates containing copper(I) tend to be colorless, reflecting their d10 configuration. Structures range from linear 2-coordinate, trigonal planar, and tetrahedral molecular geometry. Examples include linear and trigonal planar . Cyanide gives analogous complexes but also the trianionic tetracyanocuprate(I), . Dicyanocuprate(I), , exists in both molecular or polymeric motifs, depending on the countercation.

Copper(II)

Cuprates containing copper(II) include trichlorocuprate(II), , which is dimeric, and square-planar tetrachlorocuprate(II), , and pentachlorocuprate(II), . 3-Coordinate chlorocuprate(II) complexes are rare.

Tetrachlorocuprate(II) complexes tend to adopt flattened tetrahedral geometry with orange colors.

Sodium tetrahydroxycuprate(II) () is an example of a homoleptic (all ligands being the same) hydroxide complex. :

Copper(III) and copper(IV)

Hexafluorocuprate(III) and hexafluorocuprate(IV) are rare examples of copper(III) and copper(IV) complexes. They are strong oxidizing agents.

Organic cuprates

Main article: Organocopper compound

Cuprates have a role in organic synthesis. They are invariably Cu(I), although Cu(II) or even Cu(III) intermediates are invoked in some chemical reactions. Organic cuprates often have the idealized formulas and , both of which contain copper in an oxidation state of +1, where R is an alkyl or aryl. These reagents find use as nucleophilic alkylating reagents.

References

References

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