The reaction is often performed in the presence of charcoal as a catalyst, or hydrogen peroxide is employed in place of air. For example, the presence of ammonia triggers the oxidation of cobalt(II) chloride to hexamminecobalt(III) chloride:Ĥ CoCl 2♶H 2O + 4 NH 4Cl + 20 NH 3 + O 2 → 4 Cl 3 + 26 H 2O In the presence of ammonia or amines, cobalt(II) is readily oxidised by atmospheric oxygen to give a variety of cobalt(III) complexes. THF in pentane produces the brown, thermally stable cobalt(IV) tetralkyl - a rare example of a stable transition metal/saturated alkane compound, different products are obtained in other solvents.Reaction of 1-norbonyllithium with the CoCl 2 This 19-electron species is a good reducing agent, being readily oxidised to the yellow 18-electron cobaltacenium cation. Reaction of the anhydrous compound with sodium cyclopentadienide gives cobaltocene. In the laboratory, cobalt(II) chloride serves as a common precursor to other cobalt compounds. The structure of a cobalt(IV) coordination complex with the norbornyl anion The 2− ion is the blue ion that forms upon addition of hydrochloric acid to aqueous solutions of hydrated cobalt chloride, which are pink. Salts of the anionic complex CoCl 4 2− can be prepared using tetraethylammonium chloride: CoCl 2 + 2 Cl → 2 The adducts are usually either octahedral or tetrahedral. CoCl 2♶H 2O and CoCl 2 are weak Lewis acids. Such solutions give a precipitate of CoS upon treatment with H 2S. Generally, aqueous solutions of cobalt(II) chlorides behave like other cobalt(II) salts since these solutions consist of the 2+ ion regardless of the anion. Upon heating, the hexahydrate dehydrates. Hydrated cobalt chloride is prepared from cobalt(II) hydroxide or cobalt(II) carbonate and hydrochloric acid:ĬoCO 3 + 2 HCl + 5 H 2O → Co(H 2O) 6Cl 2 + CO 2 CoCl 2♶H 2O is deliquescent, and the anhydrous salt CoCl 2 is hygroscopic, readily converting to the hydrate. Concentrated aqueous solutions are red at room temperature but become blue at higher temperatures. This species dissolves readily in water and alcohol. In the solid state CoCl 2♶H 2O consists of the molecule trans- and two molecules of water of crystallization. Aqueous solutions of both CoCl 2 and the hydrate contain the species 2+.
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