One of abundant iron assembles in Nature is Fe4X4-cubanes (X = S, O): iron-sulfur motifs constitute the electron-transfer components of several ferredoxins, whereas Fe4O4-units are present in iron minerals. [Fe8(�4-O)4(�-4-R-pz)12X4] compounds (R = H, Cl, Br, Me; X = Cl, Br, NCS, OAr; pz = pyrazolate-anion), containing a Fe4O4-cubane core encapsulated inside a shell of four Fe(4-R-pz)3Cl units, can reversibly and consecutively accept up to four electrons across a potential window ~1.1 V. Mixed-valent Fe8-compounds, obtained by chemical reduction, have been studied by UV-Vis-NIR, IR, M�ssbauer spectroscopy and X-ray crystallography. Singly-reduced compounds display temperature-independent electron delocalization over the four Fe4O4-cubane Fe-sites. In contrast, the behavior of a twice-reduced [Fe8(�4-O)4(�-4-Cl-pz)12X4]2- species depends on terminal anions: a transition from a delocalized to localized valence in cubane happens upon cooling when X- = Cl-, whereas full localization of two extra electrons on outer Fe-sites was observed even at r.t. when X- = NCS-.

Mixed-valent octanuclear iron complexes with Fe<sub>4</sub>O<sub>4</sub>-cubane core

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Mixed-valent octanuclear iron complexes with Fe4O4-cubane core

Mixed-valent octanuclear iron complexes with Fe₄O₄-cubane core