EXAFS determinations of uranium structures: the uranyl ion complexed with tartaric, citric, and malic acids

The solution structures of the uranyl complexes formed in 1:1 mixtures of uranyl ion with tartaric, malic and citric acids were determined by extended X-ray absorption fine-structure spectroscopy. The results indicated the presence of a uranyl dimer as shown by the characteristic uranium-oxygen interactions of the uranyl ion and U-U interactions at 3.92 angstrom. Analysis showed that the dimer is the ligand-bridged species (UO2)2(L)2.