Iron (II) complexes of the tridentate tris(pyrrolide)ethane (tpe) ligand were synthesized and tested for reactivity with outer-sphere and inner-sphere chemical oxidants. The products were thoroughly characterized by X-ray crystallography, NMR, EPR and Mossbauer spectroscopy and DFT calculations, and showcase three disparate redox transformation types. The first, outer-sphere oxidation, resulted in a degradative H-atom abstraction to the tpe ligand. The second, inner-sphere oxidation, achieved through the use of coordinating one- or two-electron oxidants, produced isolable, formally iron (III) complexes. The third redox transformation observed was a reversible one-electron transfer to the pi-system of a bulky diazomethane ligand, which produced a formally iron (III) complex anti-ferromagnetically coupled to a ligand-borne radical. The factors governing redox reaction pathways for a given molecule are illustrated by examining these redox modes together on one complex.

Access to three disparate redox pathways of iron tris(pyrrolido)ethane complexes: Outer sphere, inner sphere, and reversible electron transfers

243rd National Meeting (2012)

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