Oxidation of the Ferrous Precursors

This leads to interesting and predictable differences between complexes of the isomeric pentadentate ligands and L. The redox potentials, electron transfer kinetics, and oxidation/oxygenation reactivities of the corresponding high-valent iron complexes as well as the Fe CH202 chemistry have been studied in detail (K. Benzing, P. Comba, A.-M. Rensland, and S. Wunderlich, unpublished data) 

35] and shown to be very efficient oxidation catalysts (see Section 6.6) [20a-c, 35, 

A thorough DFT-based theoretical analysis of the formation of [(L )Fe = O(OH)] indicates that the most favorable process in this system is a direct transformation of the initially formed Fe VH202 adduct to the novel [(L )Fe (OH)2] product [I3Q. This may explain why in the L -based iron chemistry it is difficult to trap Fe intermediates. However, reaction pathways and stabilities of intermediates depend on the solvent this also emerges from the spin equilibrium of the [(L )Fe (OOBuf)] system described above [37] and from the DFT analysis of the L -based Fe VH202 system which indicates that a number of steps are assisted by H2O molecules in the second coordination sphere [13f], 

---