Cyano lambda3-iodanes react with iron(II) and iron(III) complexes as cyano-transfer one-electron oxidants. This approach enables the straightforward synthesis of iron(III) and iron(IV) cyanide complexes, which have been thoroughly characterized by spectroscopic methods, including X-ray diffraction, EPR, Mössbauer and NMR spectroscopies and computational methods.
We disclose a new reactivity mode for electrophilic cyano lambda3-iodanes as group transfer one-electron oxidants to synthesize FeIII and FeIV cyanide complexes. The inherent thermal instability of high-valent Fe(IV) compounds without pi-donor ligands (such as oxido (O2–), imido (RN2–) or nitrido (N3–)) makes their isolation and structural characterization a very challenging task. We report the synthesis of an FeIV cyanide complex [(N3N’)FeCN] (4) by two consecutive single electron transfer (SET) processes from Fe(II) precursor [(N3N’)FeLi(THF)] (1) with cyanobenziodoxolone (CBX). The Fe(IV) complex can also be prepared by reaction of [(N3N’)FeIII] (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 [(N3N’)FeIII(CN)(Li)(THF)3] (2-LiTHF). Complexes 4 and 2-LiTHF have been structurally characterized by single crystal X-ray diffraction and their electronic structure has been examined by Mössbauer, EPR spectroscopy, and computational analyses.
C. Souilah, S.A.V. Jannuzzi, D. Demirbas, S. Ivlev, M. Swart, S. DeBeer and A. Casitas
“Synthesis of Fe(III) and Fe(IV) Cyanide Complexes Using Hypervalent Iodine Reagents as Cyano-Transfer One-Electron Oxidants”
Angew. Chem. Int. Ed. 2022, ASAP
Girona, March 18, 2022
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