Pulse radiolysis of aqueous indium(III) perchlorate solutions

The formation and decay of In(II) in the acid pH range was investigated. Hydrated electrons react with In³⁺ with a rate constant of (2.8±0.4) x 10¹⁰M^-1s^-1 (ionic strength, 0.09 M). Isopropanol radicals and H atoms did not react with In³⁺. Other forms of In(III), such as InOH²⁺, its dimer and the In(III) tetramer were unimportant under our conditions. In²⁺ is an acid, pK= 4.5±0.2. It decays away by disproportionation (k= (1.3±0.3) x 10⁹ M^-1 s^-1, oxidizes isopropanol radicals (k=(9.0±2.0) x 10⁸M^-1 s^-1) and reduces H₂O₂ (k= 6.0±1.0) x 10⁸ M^-1 s^-1). In⁺ is obtained as a relatively stable product by the reduction of In²⁺ with isopropanol radicals and by disproportionation of In²⁺.