Cations aquated

The extraction of gold from PGM solutions by dibutyl carbitol is used by Inco,226 whereas extraction by methyl isobutyl ketone is used by Matthey Rustenburg Refiners.224 In both instances, the extraction of the gold immediately precedes the respective extraction steps for palladium described previously. Base-metal anions, such as FeCl4 , which are extracted at high concentrations of aqueous chloride, can be removed by contacting the loaded organic phase with water or dilute hydrochloric acid. Under these conditions, the base-metal chloro anions are converted to the aquated cations, e.g. 

Chapter 6 Aquated cations formation and acidic properties 171... 

Aquated cations can act as Bronsted acids by loss of H+ from a coordinated water molecule (equation 6.32). 

Those exhibiting strong fluorescence as aquated cations but with weak molecular fluorescence and phosphorescence when complexed e.g. Eu " and Tb " and, to a much lesser extent, Dy and Sm. The strong fluorescence of the cations is the result of efficient intramolecular energy transfer and relatively weak decay. 

The kinetic reactivity/lability of metal complexes is especially relevant to the reaction products of aquated cations with biological substrates (ligands) and also for the use of metal complexes as therapeutic agents. 

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