Aquopentaammineiridium III Perchlorate

For the preparation of the acidopentaammine series the appropriate intermediate complex is the aquo compound, which is conveniently made from the chloro complex in a way which 

The chloride [Ir(NH3)6Cl]Cl2 (3 g.) is dissolved in a solution of sodium hydroxide (100 ml. of a 1 M solution) and refluxed for 8 hours. The red-brown solution is filtered in order to remove impurities. To the filtrate 10-12 ml. of 60% perchloric acid is carefully added white crystals form. The product is collected on a filter washed with 1 M HC104 and with alcohol. For purification the crystals are dissolved in about 40 ml. of warm (40°C.) water. After filtration from some gelatinous residue, the product is recovered by precipitation with 2 ml. of 60% HCIO4. The white crystals are washed by dilute HCIO4 and alcohol and dried in a desiccator over silica gel. Yield is 3.2-3.4 g. (69-73%). Anal. Calcd. for [Ir(NH3)6-(H20)](C104)3 Ir, 32.4 N, 11.8 H, 2.89 Cl, 17.91. Found Ir, 32.23 N, 11.9 H, 3.02 Cl, 18.13. 

Typical absorption bands in the ultraviolet are 38,800 and 47,000 cm.-1 with molar extinction coefficients of 86 and 128, respectively. The compound is soluble in H20 and almost insoluble in ethanol, acetone, or ether. 

The acido complexes [IrtNH jXp (X = I, Br, CHOCT, CH3COO-, N03-) for which the corresponding acids are easily available can be prepared according to the procedure given for the aquo compound. Instead of using HC104, the aquo salts are precipitated by the respective acid. The corresponding 

The anion X can be substituted, either by repeated precipitation with a different acid HY or by passing through an anion exchanger.4 

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