Cuprates
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Cuprates (from Latin cuprum for copper) are chemical compounds that contain an anion containing copper . Several different types of cuprates can be distinguished.
Cuprates in complexes
Cuprate anions form in complexes with negatively charged ligands such as cyanide , hydroxide or halides . Typical representatives of these complexes are tetracyanocuprate (I), [Cu (CN) 4 ] 3− , tetrachlorocuprate (II) [CuCl 4 ] 2− or hexahydroxocuprate (II) [Cu (OH) 6 ] 4− . The complex compounds are so stable that with hydrogen sulphide no copper (II) sulfide more fails. There are also rare copper (III) and copper (IV) complexes such as hexafluorocuprate (III) [CuF 6 ] 3− or hexafluorocuprate (IV) [CuF 6 ] 2− , which are strong oxidizing agents.
Complexes with organic ligands are also known, but because of their neutral charge, these do not belong to the cuprates, but to the copper chelates .
Copper complexes often show a characteristic color. Copper (I) complexes are red-brown, copper (II) complexes turquoise to intense blue, copper (III) and copper (IV) complexes orange-red.
Organic cuprates
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Cuprates play an important role in organic copper compounds . They contain the R 2 Cu - anion. Depending on the counterion present, a distinction is made between Gilman - (with lithium as counterion), Normant - ( magnesium and a halide as counterion) and bone cuprates ( zinc and a halide as counterion, an organic residue is replaced by cyanide).
Salty cuprates
The + III oxidation state, which is otherwise rarer in copper, occurs in the CuO 2 - anion. This occurs, for example, in YBCO and plays an important role in high-temperature superconductivity .
literature
- Entry to Cuprates. In: Römpp Online . Georg Thieme Verlag, accessed on July 14, 2014.
- E. Riedel, C. Janiak: Inorganic Chemistry . 7th edition with DVD. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-018903-2 , pp. 748-752