Tetraammine copper -hydroxide

Tetramino Cupric Nitrate [or Tetraammine copper(II)nitrate]. [Cu(NH3)4](N03)2 mw255.73 N 32.87% purple monocl cryst. Sol in ammonia and w. Prepn is by addn of aq amm hydroxide to an aq soln of cupric nitrate with stirring at 5°. 

Similarly, on the addition of strong ammonia, a base (in water, NH3 -h OH2 NH4 -h OH all four species are present), little by little to a blue aqueous solution of cop-per(II) sulfate, the final soluble species is the complex tetraammine-copper(II) ion its stability is clear from the fact that it is formed by the dissolution [Eq. (2)] of the intermediate solid [Eq. (1)]. This solid is basic copper(II) sulfate, known also as several minerals (brocchantite, lan-gite, wroewulfite) in oxidized sulfide ore zones. The word basic in the name simply reflects the presence of the hydroxide ion. OH , the basic constituent of water. 

Binary Copper(ll) Compounds. Black crystalline CuO is obtained by pyrolysis of the nitrate or other oxo salts above 800° it decomposes to CuzO. The hydroxide is obtained as a blue bulky precipitate on addition of alkali —hydroxidenxrcuprkrsolutions warming an aqueous slurry dehydrates this to the oxide. The hydroxide is readily soluble in strong acids and also in concentrated alkali hydroxides, to give deep blue anions, probably of the type [Cu (OH)2 2]2+. In ammoniacal solutions the deep blue tetraammine complex is formed. 

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