Understanding the mechanism of H(+)-induced demetalation as a design strategy for robust iron(III) peroxide-activating catalysts

J Am Chem Soc. 2003 Oct 15;125(41):12378-9. doi: 10.1021/ja0367344.

Abstract

The FeIII-TAML (tetra-amido macrocyclic ligand) activators 1 (Y = Cl) and 2 (Y = H2O), a (R = Me, X = H), b (Me, Cl), c (Me, MeO), d (Et, Cl), e (F, H), f (F, Cl), are five-coordinated in the solid state (X-ray crystallography) but are six-coordinated species in water with two H2O axial ligands. The first pKa's of aqueous ligands are in the range of 9.5-10.5. The acid-induced demetalation of 2 follows the equation kobs = k1*[H+] + k3*[H+]3. The rate constants k1* and k3* vary by 5 and 11 orders of magnitude depending on the nature of substituents R. The highest stabilization against the demetalation is achieved for R = F.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biomimetic Materials / chemistry
  • Biomimetic Materials / metabolism
  • Catalysis
  • Crystallography, X-Ray
  • Ferric Compounds / chemistry*
  • Ferric Compounds / metabolism
  • Hydrogen-Ion Concentration
  • Kinetics
  • Oxidation-Reduction
  • Peroxides / chemistry*
  • Peroxides / metabolism
  • Protons

Substances

  • Ferric Compounds
  • Peroxides
  • Protons