The hydrolysis of hexaiodoplatinate(IV)

Abstract

The hydrolysis of the hexaiodoplatinate(IV) complex in aqueous solution has been studied by spectrophotometric and potentiometric techniques. The reaction proceeds in three stages which are ascribed to the stepwise loss of three iodide ions. The platinum(IV) complexes are in labile equilibrium with an increasing proportion of platinum(II) species as hydrolysis proceeds, and approximate values of the hydrolysis and reduction constants have been estimated, together with a value for the acid dissociation constant of the aquopentaiodoplatinate(IV) ion. The rates of the three stages have been measured and the apparent activation energy for the first stage is 12·5 kcal./mole. The mechanisms involved in the three stages are complex, and are not all the same, although some mechanisms, known to be followed in reactions of other halogenoplatinum(IV) complexes, can be rejected.