Cuprate
Metallic compound with anionic copper complexes
- 2 min read
- 3 chapters
Related on Lably
Through Copper, Coordination complex and Oxidation state
Organic cuprates typically have a CuR2− formula, corresponding to a copper(I) oxidation state, where at least one of the R groups can be any organic group. These compounds are frequently used in organic synthesis as weak nucleophiles that preferentially attack π bonds. An example of an organic cuprate is dimethylcuprate(I) anion [Cu(CH3)2]−.
Inorganic cuprate complexes have a wide variety of formulas. An inorganic cuprate example is the tetrachloridocuprate(II) or tetrachlorocuprate(II) (CuCl42−) anion, a copper(II) atom coordinated to four chloride ions.
Cuprate oxide salts are layered materials with general formula XYCumOn, and some are non-stoichiometric. Many of these compounds are known for their superconducting properties.
Oxide cuprates
Many stable or metastable alkali metal cuprates(III) are known, all salts of the polyanion [CuO2−]n. 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) KCuO2. Even so, KCuO2 is a non-stoichiometric compound, so the more exact formula is KCuOx 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 YBa2Cu3O7, 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.
Sign in to keep reading
2 more chapters are free with a Lably account.
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 § Organic cuprates).
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 CuCl2− and trigonal planar CuCl32−. Cyanide gives analogous complexes but also the trianionic tetracyanocuprate(I), [Cu(CN)4]3−. Dicyanocuprate(I), [Cu(CN)2]−, exists in both molecular or polymeric motifs, depending on the countercation.
Copper(II)
Cuprates containing copper(II) include trichlorocuprate(II), CuCl3−, which is dimeric, and square-planar tetrachlorocuprate(II), CuCl42−, and pentachlorocuprate(II), CuCl53−. 3-Coordinate chlorocuprate(II) complexes are rare.
Tetrachlorocuprate(II) complexes tend to adopt flattened tetrahedral geometry with orange colors.
Sodium tetrahydroxycuprate(II) (Na2Cu(OH)4) is an example of a homoleptic (all ligands being the same) hydroxide complex.
- Cu(OH)2 + 2 NaOH → Na2Cu(OH)4
Copper(III) and copper(IV)
Hexafluorocuprate(III) CuF63− and hexafluorocuprate(IV) CuF62− are rare examples of copper(III) and copper(IV) complexes. They are strong oxidizing agents.
Organic cuprates
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 CuR2− and CuR32−, 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.