Synthesis of Fe and Fe Cyanide Complexes Using Hypervalent Iodine Reagents as Cyano-Transfer One-Electron Oxidants.

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