Copper complexes aqueous solution chemistry

Arsonium salts have found considerable use in analytical chemistry. One such use involves the extraction of a metal complex in aqueous solution with tetraphenyiarsonium chloride in an organic solvent. Titanium(IV) thiocyanate [35787-79-2] (157) and copper(II) thiocyanate [15192-76-4] (158) in hydrochloric acid solution have been extracted using tetraphenyiarsonium chloride in chloroform solution in this manner, and the Ti(IV) and Cu(II) thiocyanates deterrnined spectrophotometricaHy. Cobalt, palladium, tungsten, niobium, and molybdenum have been deterrnined in a similar manner. In addition to their use for the deterrnination of metals, anions such as perchlorate and perrhenate have been deterrnined as arsonium salts. Tetraphenyiarsonium permanganate is the only known insoluble salt of this anion. 

In water, the cuprous ion, Cu+, may not exist in appreciable quantities, for it disproportionates (dismutates) into the cupric ion, Cu2+, and copper metal. Certain very slightly dissociated complexes of univalent copper (for example, Cu(CN)J3 and CuClJ") are stable in aqueous solutions and relatively insoluble cuprous compounds (for example, CuCl, and CU2O) may survive in the presence of water if strong oxidizing agents are not also present. The iodide, Cul, and sulfide, Cu2S, are particularly stable. Aside from the instability of the hydrated Cu+ ion, the chemistry of univalent copper is quite similar to that of univalent silver. 

The first preparation of a chalcogenocarboxylato copper complex was described in the article by Engelhardt et al. [62] in 1868, who prepared thioben-zoic acid copper from the reaction of potassium thiobenzoate with CUSO4 in aqueous solution. The chemistry of this class of compounds, however, is not... 

The Cupric, Cu2+ or Cu(II) State, 3d9 The most important and stable oxidation state for copper is divalent. There is a well-defined aqueous chemistry of the Cu2+ ion, which generates the familiar blue solution when complexed with water. A large number of copper coordination compounds exist and these have been studied extensively. A strong Jahn-Teller distortion is associated with the 3d9 electronic configuration of this ion. This implies that a regular tetrahedron or octahedron about the Cu2+ ion is never observed, except in the rare occurrence of a dynamic Jahn-Teller effect. The tetragonal distortion about an octahedron can lead to a square-planar coordination which is often observed in Cu(II) oxides. 

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