Electron Transfer in Metal‐Organic Molecules. A Time Resolved EXAFS and Optical Spectroscopy Study

We have measured, by means of ultrafast x‐ray absorption and optical spectroscopy, the M‐O (M=Fe, Co) and Co‐N metal to ligand bond length change as a function of time and the formation and decay of the excited states and intermediate species, after excitation with a 267 nm femtosecond pulse. These experimental data combined with DFT calculations allowed us to determine the mechanism of electron transfer operating in the redox reaction of two metal‐ligand complexes, [M(III)(C 2 O 4 ) 3 ] 3‐ and [Co(III)(NH 3 ) 6 ] 3+ . Based on the data we find that, even though both molecules are excited into their charge transfer band, the redox reaction of [M(III)(C 2 O 4 ) 3 ] 3‐ proceeds via intermolecular electron transfer while [Co(III)(NH 3 ) 6 ] 3+ electron transfer mechanism is intramolecular.