Origin of the wavelength dependence of the photoredox quantum yield for iron (III) complexes

The paper rationalizes an origin of the different experimental wavelength d ependences of the Fe-II photoformation quantum yield as a consequence of fi ve main factors, namely the different rate constant of intersystem crossing and/or internal conversion and of rovibrational relaxation, the possible e xistence of multi-channel reactivity pathways, the accessibility of several photoredox reactive states differing in lifetime, multiplicity and reactiv ity, the redox reversibility of oxidized ligand, and the efficiency of solv ent cage recombination of primary photoredox products. The issue is exampli fied on the photoredox behaviour of iron(III) chelates with anionic EDTA, a llomaltolato and oxalato ligands in aqueous media.