Complexation of Actinides(VI) with Furan-2-carboxylic and Thiophene-2-carboxylic Acids in Aqueous Solutions and Synthesis of Crystalline Compounds

Crystalline uranyl compounds with furan-2-carboxylic (F2C) and thiophene-2-carboxylic (T2C) acids containing the complex anions [UO2(OOCC4H3O) (3)](-) and [UO2(OOCC4H3S) (3)](-) were synthesized and studied by single crystal X-ray diffraction. A previously unknown compound of a transuranium element, Pu(VI), with T2C, also containing the complex anions [PuO2(OOCC4H3S) (3)](-), was synthesized. With Pu(VI) taken as example, the complexation of hexavalent actinides with F2C and T2C in aqueous solutions was studied, and the stability of the complexes PuO2L+ (L is F2C or T2C anion) was determined. The Pu(VI) complexes with F2C are slightly more stable than those with T2C but less stable than Pu(VI) monoacetate complexes. The spectral characteristics of the complexes are discussed.