Chemical elements
    Physical Properties
    Chemical Properties
      Iridium Monochloride
      Iridium Dichloride
      Iridium Trichloride
      Potassium Chloriridite
      Sodium Chloriridite
      Ammonium Chloriridite
      Aquo Chloriridites
      Iridium Tetrachloride
      Potassium Chloriridate
      Sodium Chloriridate
      Ammonium Chloriridate
      Silver Chloriridate
      Thallium Chloriridate
      Iridium Tribromide
      Iridium Tetrabromide
      Potassium Bromiridate
      Sodium Bromiridate
      Ammonium Bromiridate
      Iridium Oxybromide
      Iridium Tri-iodide
      Potassium Iodiridite
      Iridium Tetra-iodide
      Potassium Iodiridate
      Iridium Monoxide
      Iridium Sesquioxide
      Iridium Dioxide
      Iridium Trioxide
      Iridium Monosulphide
      Iridium Sesquisulphide
      Iridium Disulphide
      Iridium Sesquisulphite
      Potassium Iridium Sulphite
      Iridium Sesquisulphate
      Potassium Iridium Alum
      Ammonium Iridium Alum
      Caesium Iridium Alum
      Rubidium Iridium Alum
      Iridium Disulphate
      Iridium Sesquiselenide
      Hydrogen Iridi-nitrite
      Potassium Iridi-nitrite
      Sodium Iridi-nitrite
      Ammonium Iridi-nitrite
      Hydrogen Iridicyanide
      Potassium Iridicyanide
      Barium Iridicyanide
    PDB 1c1k-4enb

Iridium Tetrachloride, IrCl4

Iridium Tetrachloride, IrCl4, has been prepared in a variety of ways, notably:
  1. By evaporating ammonium chloriridate, (NH4)2IrCl6, with aqua regia or chlorine water, whereby the ammonia is expelled.
  2. By dissolving iridium black or the dioxide in hydrochloric acid. The solution is concentrated and any trichloride converted into tetrachloride by addition of aqua regia. The product is dried in vacuo, whereby a brownish black amorphous residue is obtained which is very hygroscopic and soluble in water.
  3. Iridium tetrachloride may also be obtained by direct union of the elements, the chlorine being introduced under high pressure. Thus at 60° C., in the presence of liquid chlorine, under a pressure of about 20 atmospheres, iridium was gradually converted into the tetrachloride in five days; whilst a year was required at 15° C. under a pressure of 8 atmospheres.

    Iridium tetrachloride has been obtained crystallised in the form of tetrahedra, but in this form it contains water, which is expelled, together with hydrogen chloride, on heating. At higher temperatures metallic iridium alone is left as residue.

    Iridium tetrachloride is readily reduced to the trichloride. Its aqueous solution, on dilution, yields hypochlorous acid and the trichloride. On boiling, a precipitate of oxychloride is obtained. Addition of excess of alkali precipitates part of the iridium as dioxide, the remainder staying in solution as sesquioxide, being precipitated only upon neutralisation of the alkali. Addition of alcohol to the alkaline solution precipitates metallic iridium, aldehydes and alkali formates being simultaneously produced. Reducing agents, such as stannous chloride, sulphur dioxide, nitric oxide, hydrogen sulphide, ferrous sulphate, etc., convert the tetrachloride into trichloride.

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