The rates of reduction of the nickel(III) oxime-imine complexes, [Ni(III)(Me2L)]+ and [Ni(III)(Me2LH)]2+ by the corresponding iron(II) species are determined. Comparisons with rates calculated with the use of Marcus theory reveal that reactions of [Fe(III)(Me2LH)]+, where the electron transfer product is the highly acidic [Fe(III)(Me2LH)]2+, show rate enhancements of several orders of magnitude. These are ascribed to a strong coupling of the electron transfer with the concomitant, thermodynamically favorable proton transfer. A free energy correlation supports this conclusion.
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The authors thank CAPES (Brazil) for a maintenance grant to M.C.M.L.
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- Electron transfer
- Iron complexes
- Nickel complexes
- Oxime-imine complexes
- Proton transfer