Electron transfer in the tris(2,2'-bipyridine)ruthenium(2+)-methylviologen(2+) system in acetonitrile-water mixtures. Dependence on transfer distance, ionic strength and temperature
- Publication Type
- Journal contribution
- Authors
- Greiner, G.; Pasquini, P.; Weiland, R.; Orthwein, H.; Rau, H.
- Year of publication
- 1990
- Published in
- J. Photochem. Photobiol., A
- Band/Volume
- 51/2
- Page (from - to)
- 179-95
The solvent dependence of the quenching of hydrocarbon-substituted Ru[(CnH2n+1)2bpy]32+ complexes by methylviologen MV2+ and the recombination of the free ions formed in the quenching reaction were investigated in acetonitrile-water mixts. The quenching rate is lower for the complexes with longer hydrocarbon chains, but this is not the case for the rate of the back reaction of the free ions. Both the quenching and the recombination rate consts. have a min. when plotted vs. solvent compn., between 40 and 60 mol.% of acetonitrile. The influences of ionic strength and of the charges carried by the redox partners were investigated. The activation parameters of the quenching reaction were also detd. from the temp. dependence of the quenching consts. Calcns. of the rate consts. assuming adiabatic or non-adiabatic conditions do not reproduce the exptl. min. However, this appears when an Arrhenius formula is used contg. the exptl. activation parameters and the longitudinal relaxation time .tau.L of the solvent mixts.