New Insight into Photochemistry of Ferrioxalate.

Optical spectroscopy and nanosecond flash photolysis (Nd:YAG laser, 355 nm, pulse duration 5 ns, mean energy 5 mJ/pulse) were used to study the photochemistry of Fe III(C 2O 4) 33−complex in aqueous solutions. The main photochemical process was found to be intramolecular electron transfer from the ligand to Fe(III) ion with formation of a primary radical complex [(C 2O 4) 2Fe II(C 2O 4•)] 3−. The yield of radical species (i.e., CO 2• −and C 2O 4• −) was found to be less than 6% of Fe III(C 2O 4) 33−disappeared after flash. [(C 2O 4) 2Fe II(C 2O 4•)] 3−dissociates reversibly into oxalate ion and a secondary radical complex, [(C 2O 4)Fe II(C 2O 4•)] −. The latter reacts with the initial complex and dissociates to Fe II(C 2O 4) and oxalate radical. In this framework, the absorption spectra and rate constants of the reactions of all intermediates were determined. [ABSTRACT FROM AUTHOR]