Chemical elements
    Physical Properties
    Chemical Properties
      Ruthenium Fluoride
      Ruthenium Dichloride
      Ruthenium Trichloride
      Potassium Chlor-ruthenate
      Potassium Aquo-chlor-ruthenate
      Caesium Aquo-chlor-ruthenate
      Ruthenium Oxychlorides
      Potassium Bromruthenite
      Potassium Bromruthenate
      Potassium Aquobromruthenate
      Ruthenium Tri-iodide
      Ruthenium Sesquioxide
      Hydrated Ruthenium Sesquioxide
      Ruthenium Dioxide
      Ruthenium Tetroxide
      Ruthenium Sesquisulphide
      Ruthenium Disulphide
      Ruthenium Trisulphide
      Ruthenium Sesquisulphite
      Ruthenium Dithionate
      Ruthenium Sulphate
      Ruthenium Nitrosotrihydroxide
      Potassium Nitrosochloivifuthenate
      Ammonium Nitrosochlor-ruthenate
      Rubidium Nitrosochlor-ruthenate
      Potassium Ruthenium Nitrite
      Sodium Ruthenium Nitrite
      Ruthenium Dicarbonyl
      Potassium Ruthenocyanide
      Barium Ruthenocyanide
      Strontium Ruthenocyanide
      Ruthenium Silicide
    PDB 1bex-4e7y

Potassium Ruthenocyanide, K4Ru(CN)6

Potassium Ruthenocyanide, K4Ru(CN)6.3H2O, is obtained by heating to the point of fusion ammonium chlor-ruthenate with a slight excess of potassium cyanide for ten to fifteen minutes. Extraction of the melt with boiling water and subsequent evaporation yields crystals of potassium ruthenocyanide.

Howe has prepared the salt in a variety of ways, the three yielding the best results were as follows:
  1. Fusion of potassium ruthenium nitrosoehloride with potassium cyanide. This gave a somewhat better yield than the method of Claus.
  2. Ruthenium trichloride fused with potassium cyanide.
  3. The melt formed by fusion of ruthenium in potassium hydroxide and nitrate, and thus containing potassium ruthenate, was dissolved in water and boiled with potassium cyanide. The orange colour was quickly bleached, the ruthenocyanide produced being subsequently isolated by crystallisation.
Potassium ruthenocyanide crystallises in square pseudo-rhombic plates, isomorphous with the corresponding ferro- and osmo-cyanides. Its solution in water yields no precipitate with salts of the alkaline earth metals as their ruthenocyanides are soluble. Ferric chloride gives a rich purple precipitate resembling Prussian blue in its chemical properties. Soluble in pure water it is precipitated by salts or alcohol. When precipitated in cotton fibre it adheres well, imparting its own beautiful colour. Alkalies decompose the salt, which, however, is re-formed on addition of dilute acid. This constitutes a useful test for ruthenocyanides.

Ferrous sulphate yields, with potassium ruthenocyanide, a pale blue precipitate which gradually oxidises to the purple one on standing, but instantly on addition of bromine.

With hydrochloric acid hydrogen cyanide is evolved on warming, . and after a time a deep violet-blue precipitate of ruthenium cyanide with a little potassium cyanide is obtained. Chlorine colours the solution brownish yellow, possibly in consequence of the formation of a ruthenicyanide, although no crystalline salt can be isolated from it.

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