Successive light-induced two electron transfers in a Ru-Fe supramolecular assembly: from Ru-Fe(II)-OH2 to Ru-Fe(IV)-oxo

In the present work we describe the synthesis and study of a Ru-II-Fe-II chromophore-catalyst assembly designed to perform the light-induced activation of an iron bound water molecule and subsequent photo-driven oxidation of a substrate. Using a series of spectroscopic techniques, we demonstrate that excitation of the chromophore unit with 450 nm light, in the presence of a sacrificial electron acceptor, triggers a cascade of electron transfers leading to the formation of a high valent iron(IV)-oxo center from an iron(II)-bound water molecule. The activity of this catalytic center is illustrated by the oxidation of triphenyl phosphine.