Photolysis of FeOH²⁺ and FeCl²⁺ in Aqueous Solution. Photodissociation Kinetics and Quantum Yields

Photodissociation of FeOH2+ and FeCl2+ complexes has been studied by pulsed laser spectroscopy (λ = 347 nm) techniques. Transient bleaching of FeOH2+ was observed due to the dissociation FeOH+ → Fe2+ + OH• (at λ = 347 nm). The observed bleaching involved the photoreduction of the species FeOH2+ to iron(II) complexes. These latter species showed a much lower absorption. Concomitant formation of the Cl2•- anion radical was observed due to the reactions FeCl2+ → Fe2+ + Cl• (at λ = 347 nm) and Cl• + Cl- → Cl2•-. The experimental findings allowed us to suggest a reaction sequence involving Cl•, Cl2•-, ClOH•- and OH• radicals. The quantum yields found by laser kinetic spectroscopy for FeOH2+ and FeCl2+ photodissociation were 0.21 ± 0.04 and 0.5 ± 0.1, respectively.

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