Photochemistry of uranium(IV) 1,3-diketonates in organic solvents

Abstract

Electronic spectra of tetrakis(acetylacetonato)- and tetrakis(dibenzoylmethanato)-uranium(IV) have been investigated. Irradiations at the wavelengths of the intraligand and ligand-to-metal charge-transfer transitions of these chelates cause reduction of U^IV to U^III as the primary photoprocess. A secondary thermal reaction in halogenocarbon solvents leads to reoxidation of U^III to U^IV and abstraction of halogen. Irradiation at the wave-lengths of the ƒ–ƒ transitions in the presence of oxygen induces a photo-oxygenation reaction forming bis(1,3-diketonato)dioxouranium(VI) complexes.