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Copper(I) iodide is white, but samples often appear tan or even, when found in nature as rare mineral marshite, reddish brown, but such color is due to the presence of impurities. It is common for samples of iodide-containing compounds to become discolored due to the facile aerobic oxidation of the iodide anion to molecular iodine. [4] [5] [6]
Lithium dimethylcopper (CH 3) 2 CuLi can be prepared by adding copper(I) iodide to methyllithium in tetrahydrofuran at −78 °C. In the reaction depicted below, [4] the Gilman reagent is a methylating reagent reacting with an alkyne in a conjugate addition, and the ester group forms a cyclic enone. Scheme 1. Example Gilman reagent reaction
Phenylcopper was the first known organocopper compound and was first prepared in 1923 from phenylmagnesium iodide and copper(I) iodide and in 1936 by Henry Gilman by transmetallation of phenylmagnesium iodide with copper(I) chloride. Phenylcopper can be obtained by reacting phenyl lithium with copper(I) bromide in diethyl ether. [3]
In addition the four copper atoms form a planar Cu 4 ring based on three-center two-electron bonds. The copper to copper bond length is 242 pm compared to 256 pm in bulk copper. In pentamesitylpentacopper a 5-membered copper ring is formed, similar to (2,4,6-trimethylphenyl)gold, and pentafluorophenylcopper is a tetramer. [9]
Some copper proteins form oxo complexes, which also feature copper(III). [20] With tetrapeptides, purple-colored copper(III) complexes are stabilized by the deprotonated amide ligands. [21] Complexes of copper(III) are also found as intermediates in reactions of organocopper compounds. [22] For example, in the Kharasch–Sosnovsky reaction.
Copper is a chemical element with the symbol Cu (from Latin: cuprum) and the atomic number of 29. It is easily recognisable, due to its distinct red-orange color.Copper also has a range of different organic and inorganic salts, having varying oxidation states ranging from (0,I) to (III).
The aromatic chlorides and bromides are not easily substituted by iodide, though they may occur when appropriately catalyzed. The so-called "aromatic Finkelstein reaction" is catalyzed by copper(I) iodide in combination with diamine ligands. [9] Nickel bromide and tri-n-butylphosphine have been found to be suitable catalysts as well. [10]
Marshite (CuI) is a naturally occurring isometric halide mineral with occasional silver (Ag) substitution for copper (Cu). [6] [7] Solid solution between the silver end-member miersite and the copper end-member marshite has been found in these minerals from deposits in Broken Hill, Australia. [8]