Synthesis of Fe(III) and Fe(IV) Cyanide Complexes Using Hypervalent Iodine Reagents as Cyano‐Transfer One‐Electron Oxidants

We disclose a new reactivity mode for electrophilic cyano λ(3)‐iodanes as group transfer one‐electron oxidants to synthesize Fe(III) and Fe(IV) cyanide complexes. The inherent thermal instability of high‐valent Fe(IV) compounds without π‐donor ligands (such as oxido (O(2−)), imido (RN(2−)) or nitrido (N(3−))) makes their isolation and structural characterization a very challenging task. We report the synthesis of an Fe(IV) cyanide complex [(N(3)N′)FeCN] (4) by two consecutive single electron transfer (SET) processes from Fe(II) precursor [(N(3)N′)FeLi(THF)] (1) with cyanobenziodoxolone (CBX). The Fe(IV) complex can also be prepared by reaction of [(N(3)N′)Fe(III)] (3) with CBX. In contrast, the oxidation of Fe(II) with 1‐cyano‐3,3‐dimethyl‐3‐(1H)‐1,2‐benziodoxole (CDBX) enables the preparation of Fe(III) cyanide complex [(N(3)N′)Fe(III)(CN)(Li)(THF)(3)] (2‐Li(THF) ). Complexes 4 and 2‐Li(THF) have been structurally characterized by single crystal X‐ray diffraction and their electronic structure has been examined by Mössbauer, EPR spectroscopy, and computational analyses.