PHOTOREDOX PROPERTIES OF IRON(III) COMPLEXES CONTAINING GAMMA-PYRANONES

Iron(III) complexes cis-[Fe(X-benacen)(Y-K)] (X-benacen = N,N'-ethylen e-bis(4-X-benzoylacetoneiminato dianion; Y-K = anion of a substituted gamma-pyranone) undergo the inner sphere primary photoreduction of Fe( III) to Fe(II) associated with the oxidation of the Y-K- ligand when b eing irradiated into LMCT or intraligand bands in methanol. The radica ls Y-K. participate in subsequent thermal redox processes yielding bac k the anions Y-K-. The quantum yield values of the photoredox reaction depend on the phenyl substituents X of the X-benacens, on the periphe ral groups of the gamma-pyranones and on the wavelength of incident ra diation. A mechanism of deactivation processes is proposed.