A Mixed-Valence Fluorido-Bridged Fe^IIFe^III Complex

Abstract

The reaction of the\nnew dinucleating ligand susan^6‑Me with Fe­(BF₄)₂·6H₂O results\nin formation of the homovalent Fe^IIFe^II complex\n[(susan^6‑Me)­{Fe^II(μ-F)₂Fe^II}]²⁺ and the mixed-valence Fe^IIFe^III complex [(susan^6‑Me)­{Fe^IIF­(μ-F)­Fe^IIIF}]²⁺ depending on the absence\nor presence of dioxygen, respectively. Complex [(susan^6‑Me)­{Fe^IIF­(μ-F)­Fe^IIIF}]²⁺ is\nthe first molecular mixed-valence complex with a fluorido bridge.\nThe short Fe^III–μ-F bond of 1.87 Å causes\na large reorganization energy, resulting in a localized class II system\nwith an intervalence charge-transfer band of high energy at 10000\ncm^–1.