Calculation of rate constants from UV-vis spectroscopic data: an application of the Marcus-Hush model

Abstract

The MMCT band in the binuclear complex μ-cyano pentacyano ruthenium(II) pentaamminecobalt(III) was obtained in different salt solutions. A correlation of optical data with rate constants of the thermal electron transfer in a related binuclear compound was found. Combination of the spectroscopic data with the results of quantum yield measurements allows an estimation of the backward (Co → Ru) electron transfer rate constant, k b . The value of k found is about 10 12 s −1, and is shown to be equal to the preexponential factor of other rate constants corresponding to other electron transfer reactions in the binuclear complex. This analysis allows determination of all magnitudes characterizing the different optical and thermal electron transfer processes involved. Determination of these parameters is usually not possible from experiments. The present work shows how to overcome difficulties that arise when not all the required experimental information is available.