Halogen complexes precipitation

Amylose complexes (wet precipitates) were prepared with fluoro-benzene, 1,1,2,2-tetrachloroethane, 1,1,2,2-tetrabromoethane, bromo-form, and ferf-butyl alcohol. The conformation and packing of the amylose chains complexed with halogen-substituted hydrocarbons are the same as found in the complex with tert-butyl alcohol, namely,... 

The conventional preparative routes to anionic, neutral, or cationic complexes of indium start with the metal, which is dissolved in a suitable mineral acid to give a solution from which hydrated salts can be obtained by evaporation. These hydrates react with a variety of neutral or anionic ligands in nonaqueous solvents, and a wide range of indium(III) complexes have been prepared in this manner.1 Alternatively, the direct high-temperature oxidation of the metal by halogens yields the anhydrous trihalides, which are again convenient starting materials in synthetic work. In the former case, the initial oxidation of the metal is followed by isolation, solution reaction, precipitation, and recrystallization. 

Since there are a number of complexes that might conceivably be formed from most combinations of reagents (Exercise 8), the obtaining of a desired complex in substantial yield is in many cases an art. In identifying coordination compounds of cobalt, halogen atoms held in the complex ion are distinguished from anionic halides by treatment with Ag+. This precipitates anionic chloride, bromide, and iodide immediately, but eom-plexed halide precipitates only slowly. Thus, with the purpose compound... 

Of the three oxides only ZnO is amphoteric, the other two are purely basic. Thus zinc forms the most stable complex anion with oxygen, and mercury the most stable complex ions with the halogens. The hydroxides of zinc and cadmium are obtained as crystalline precipitates on the addition of alkali to solutions of the nitrates a hydroxide of mercury is unknown. 

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