Abstract
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.