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Keywords:

  • Iron;
  • Tripodal ligands;
  • Peroxides;
  • Oxidation

Abstract

The preparation and characterisation of two dinuclear iron(III) complexes with tripodal ligands 1,3-bis(2′-pyridylimino)isoindoline (indH) are presented. The μ-oxo-bridged diiron(III) complex [{FeCl(ind)}2O] (2) has been prepared by reacting FeCl3·6H2O with indH in methanol solution. Compound [{Fe(ind)(OAc)}2O] (3) was obtained from the reaction of 2 with CH3CO2Ag in THF. Both compounds were characterised by elemental analysis and UV/vis, IR, and Mössbauer spectroscopy. The X-ray structure analysis of [Fe2O(ind)2Cl2]·THF (THF) revealed a distorted trigonal bipyramidal (τ = 0.88) coordination geometry around the iron(III) ion. More importantly, 2 is a good functional model for the activation of small molecules as its 5-coordinate iron ions can easily coordinate such molecules. This is confirmed by the high catalase-like activity of 2, transforming 87% of the excess of H2O2 into O2 in 1 min. The complexes exhibited monooxygenase-like activity using H2O2 as the oxidant and oxidise alkanes to alcohols and ketones in acetonitrile in moderate yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)