Kinetics of Intramolecular Electron Transfer in Binuclear (NC)5FeII-CN-CoIII(chelate) Complexes by Picosecond Absorption Spectroscopy

Article abstract of DOI:10.1021/ja00390a002

The rates of intramolecular electron transfer in the binuclear complexes (NC)5Fe^II-CN-Co^III(chelate) (where chelate = NBETA and HEDTA) have been measured directly using picosecond absorption spectroscopy.Excitation of the Co^{III 1}T_1g <- ¹A_1g band by a 530-nm 6-ps fwhm laser pulse is followed by rapid electron transfer from Fe^II resulting in Fe^III, and Co^II in the ²E state.The subsequent decay of Fe^III occurs with a half-life of 150 ps.Our data indicate that the Co^{II 2}E state has ca.75-ps lifetime and experiences a low-spin intersystem crossing to form the ⁴T_1g ground state.The subsequent spin-permitted electron transfer back to the Fe^II species occurs in ca.95 ps.Curves calculated on the basis of this mechanism are in good agreement with the experimental data.