Intramolecular Electron Transfers Thwart Bistability in a Pentanuclear Iron Complex.

With the intention to investigate the redox properties of polynuclear complexes as previously reported for the pentamanganese complex [{MnII(μ-bpp)3}2MnIIIMnII2(μ3-O)]3+ (23+), we focused on the analogous pentairon complex that was previously isolated as all-ferrous. As Masaoka and co-workers recently published, aerobic synthesis leads to the [{FeII(μ-bpp)3}2FeIIIFeII2(μ3-O)]3+ complex (13+). This species exhibits in acetonitrile solution four reversible one-electron oxidation waves. Accordingly, the three oxidized species 14+, 15+, and 16+ with a 3FeII2FeIII, 2FeII3FeIII, and 1FeII4FeIII composition, respectively, were generated by bulk electrolysis and isolated. Mössbauer spectroscopy allowed us to determine the spin states of all the iron ions and to unambiguously locate the sites of the successive oxidations. They all occur in the μ3-oxo core except for the 14+ to 15+ process that presents a striking electronic rearrangement, with both metals in axial position being oxidized while the core is reduced to the [FeIIIFeII2(μ3-O)]5+ oxidation level. This strongly differs from the redox behavior of the Mn5 system. The origin of this electronic switch is discussed.

Références

Titre
Intramolecular Electron Transfers Thwart Bistability in a Pentanuclear Iron Complex.
Type de publication
Article de revue
Année de publication
2016
Revue
Inorg. Chem.
Volume
55
Pagination
9178–9186
ISSN
0020-1669
Soumis le 12 avril 2018