Photochemistry of PtBr62− complex in aqueous solutions. Formation and decay of Br2•− radical anions

Laser flash photolysis was applied to study the photochemistry of PtBr62− complex in aqueous solutions with the presence of free Br− anions. Laser pulse is followed by the formation of Br2
• − radical anion, which reacts with the initial complex with the rate constant k = 9 × 108 M−1 s−1 yielding the complex of Pt(V). Analysis of Br2
• − quantum yield via bromide concentration testifies that a bromine atom is formed by an electron transfer from a free Br− anion to the light-excited complex. PtBr62− photoaquation occurs via heterolytic cleavage of the Pt–Br bond. Addition of free bromide anions sufficiently decreases the quantum yield of photoaquation.