Hexadentate macrocyclic ligands containing a 1,4,7-triazacyclononane backbone and three N-bound pendent-arm phenolates form extremely stable neutral complexes with Fe III Cl 3 . The octahedral complexes [Fe III L] undergo three reversible one-electron oxidation processes to yield the mono-and dications, [FeL] and [FeL] 2 , which are stable in solution for hours, whereas the trications, [FeL] 3 , are only stable in solution on the time scale of a cyclic voltammetric experiment. These oxidations are shown to be ligand-rather than metal-centered. Three coordinated phenoxyl radicals are formed successively as shown conclusively by Mössbauer spectroscopy. The neutral, mono-, di-, and tricationic species each contain an octahedral, high-spin ferric ion (S Fe 5 2), which is intramolecularly, antiferromagnetically coupled to the spin (S 1 2) of the bound phenoxyl ligands to yield an S t 2 ground state for the monocation, and an S t 3 2 ground state for the dications as shown by EPR spectroscopy. The vibrations of the coordinated phenolate are observed by resonance Raman (RR) spectroscopy by excitation in resonance with the phenolate-to-iron charge-transfer (CT) transition above 500 nm or, alternatively, of the coordinated phenoxyl by excitation in resonance with the intraligand p 3p* transition at about 410 nm. Use of 18 O isotopomers selectively labeled at the phenolic oxygen allowed the identification of the C À O stretching and Fe À O stretching and bending modes. It is shown that the substitution pattern of phenolates and phenoxyls in their respective ortho and para positions and the charge of the complexes have a pronounced influence on the vibrational modes observed.

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