Six-Electron Chemistry of a Binuclear Fe(III) Fused Porphyrin

In this special collection dedicated to Prof. Jean-Michel Saveant, we report on the synthesis and characterization of a novel binuclear Fe(III) fused porphyrin. Ultraviolet-visible spectroscopy confirms the extended electronic structure of this macrocycle. In addition, Fourier transform infrared spectroscopy indicates the Fe centers experience a relatively rigid ligand environment as compared to a structurally related mononuclear complex featuring an 18 pi-aromatic porphyrin ligand. X-ray photoelectron and X-ray absorption near edge spectroscopies confirm the iron centers of both assemblies are Fe(III) in the as prepared, resting state. In comparison with the mononuclear porphyrin, electrochemical measurements show there is a doubling of the number of redox events associated with the fused, binuclear complex. In summary, key features of the fused-iron-porphyrin include: 1) bimetallic-iron sites, 2) a pi-extended ligand capable of delocalizing electrons across the multimetallic scaffold, and 3) the ability to store up to six electrons.