An Iron(II)[1,3-bis(2′-pyridylimino)isoindoline] Complex as a Catalyst for Substrate Oxidation with H2O2 - Evidence for a Transient Peroxidodiiron(III) Species

• Published in: European journal of inorganic chemistry 2013-08, Vol.2013 (22-23), p.3858-3866
• Main Authors: Pap, József S., Cranswick, Matthew A., Balogh-Hergovich, É., Baráth, Gábor, Giorgi, Michel, Rohde, Gregory T., Kaizer, József, Speier, Gábor, Que Jr, Lawrence
• Format: Article
• Language: English
• Subjects: Iron; N li­gands; Oxidation; Peroxido ligands; Tridentate ligands
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201300162

The complex [Fe(indH)(solvent)3](ClO4)2 (1) has been isolated from the reaction of equimolar amounts of 1,3‐bis(2′‐pyridylimino)isoindoline (indH) and Fe(ClO4)2 in acetonitrile and characterized by X‐ray crystallography and several spectroscopic techniques. It is a suitable catalyst for the oxidation of thioanisoles and benzyl alcohols with H2O2 as the oxidant. Hammett correlations and kinetic isotope effect experiments support the involvement of an electrophilic metal‐based oxidant. A metastable green species (2) is observed when 1 is reacted with H2O2 at –40 °C and has a FeIII(μ‐O)(μ‐O2)FeIII core on the basis of UV/Vis, electron paramagnetic resonance, resonance Raman, and X‐ray absorption spectroscopic data. A monoiron(II) complex of 1,3‐bis(2′‐pyridylimino)isoindoline reacts with H2O2 to form a green diiron(III) peroxido intermediate, which may serve as the precursor to the active oxidant in thioanisole and benzyl alcohol oxidation.