ONE-ELECTRON OXIDATION OF THE IRON(II) COMPLEX OF 1,10-PHENANTHROLINE-5,6-QUINONE - A PULSE-RADIOLYSIS STUDY

One-electron oxidation of the ferrous tris-PQ complex, a model for lip oxygenase, was attempted using oxidants such as .OH, N3., Br2.-, Tl2and TlOH+. .OH was found to react with the complex with a bimolecular rate constant of (3.9+/-0.6)x10(9) dm3 mol-1 s-1 , a rate which is not very dissimilar to that for the reaction with the ligand PQ. However tbe product of the reaction was found to be a OH-adduct rather than a cation radical. No reaction was found to occur with N3. o, Br2.-. Both Tl2+ and TlOH+ reacted with the complex to form its oxidised species with rate constants of (7.0+/-1)x10(8) dm3 mol-1 s-1 and (4.0+/-0.8)x1 0(8) dm3 mol-1 s-1, respectively. From a comparison of the rate consta nts and the transient spectra it was concluded that the centre of oxid ation is the ligand rather than the metal.