Details

Autor(en) / Beteiligte

• Impert, Olga
• Witwicki, Maciej
• Komarnicka, Urszula K
• Bieńko, Alina
• Niorettini, Alessandro
• Chatterjee, Debabrata

Titel

Redox reactions of a pyrazine-bridged Ru III (edta) binuclear complex: spectrochemical, spectroelectrochemical and theoretical studies

Ist Teil von

• Physical chemistry chemical physics : PCCP, 2024-01, Vol.26 (5), p.3981-3989

Ort / Verlag

England

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The redox reactions of a pyrazine-bridged binuclear [(edta)Ru pzRu (edta)] (edta = ethylenediaminetetraacetate; pz = pyrazine) have been investigated spectrochemically and spectroelectrochemically for the first time. The kinetics of the reduction of [(edta)Ru pzRu (edta)] (Ru -Ru ) with the ascorbic acid anion (HA ) was studied as a function of ascorbic concentration and temperature at a fixed pH 6.0. The overall reaction of Ru -Ru was found to consist of two-steps involving the initial formation of the mixed-valence [(edta)Ru pzRu (edta)] (Ru -Ru ) intermediate complex ( = 462 nm, = 10 000 M cm ), which undergoes further reduction by ascorbic acid to produce the [(edta)Ru pzRu (edta)] (Ru -Ru ) ultimate product complex ( = 540 nm, = 20 700 M cm ). Our studies further revealed that the Ru -Ru and Ru -Ru species are formed in the electrochemical reduction of the Ru -Ru complex at 0.0 and -0.4 V ( SHE), respectively. Formation of Ru -Ru and Ru -Ru was further corroborated by magnetic moment measurements and DFT calculations. Kinetic data and activation parameters are interpreted in terms of a mechanism involving rate-determining outer-sphere electron transfer between Ru(III) and the ascorbate monoanion (HA ) at pH 6.0. A detailed reaction mechanism in agreement with the spectral, spectro-electrochemical and kinetic data is presented. The results of the spectral and kinetic studies of the reaction of the Ru -Ru complex with molecular oxygen (O ) reveal the ability of the Ru -Ru species to effect the oxygen reduction reaction (ORR) leading to the formation of H O , a partial reduction product of dioxygen (O ).