X-RAY ABSORPTION-SPECTROSCOPY OF IRON-(II) AND IRON-(III) BASKET-HANDLE PORPHYRINS

X-Ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopies have been used to characterize iron basket-handle porphyrins in various co-ordinations, stereochemistries and oxidation states. Attention is paid to the square-planar iron(II) complexes, a dioxygen adduct of Fe(II) and a hydroxyiron(III) complex. The results are consistent with a Fe(II)(O2) rather than a Fe(III)(O2-) formulation for the dioxygen adduct. A Fe-O distance of 1.94 angstrom was found in the hydroxo complex. The kinetics of oxidation of a dioxygen form to the hydroxo complex has been studied using a dispersive-mode X-ray absorption spectrometer (half-life almost-equal-to 6 min).