Crystal Structure of An(VI) Complexes with Succinate Anions, [PuO2(C4H4O4)(H2O)] and Cs2[(AnO2)2(C4H4O4)3]•H2O (An = U, Np, Pu)

Actinide(VI) complexes with succinate anions [PuO2(succ)(H2O)] and Cs-2[(AnO(2))(2)(succ)(3)]H2O (An = U, Np, Pu), where succ = [C4H4O4](2 -), were synthesized and studied by single crystal X-ray diffraction. The compound [PuO2(succ)(H2O)] is isostructural with [UO2(succ)(H2O)] [1] and forms a three-dimensional electrically neutral framework in the crystal. The equatorial plane of the Pu(VI) pentagonal bipyramid is constituted by the O atoms of four [C4H4O4](2-) anions and one water molecule. The [C4H4O4](2-) anions are bridging; each anion is bound in the monodentate fashion with four Pu atoms. The structure of the complexes Cs-2[(AnO(2))(2)(succ)(3)]H2O is based on an anionic framework. The equatorial plane of the An(VI) hexagonal bipyramid is constituted by O atoms of three [C4H4O4](2-) anions, with each anion acting as a chelating and bridging ligand binding two An(VI) atoms. The electronic absorption spectra of [PuO2(succ)(H2O)] and Cs-2[(PuO2)(2)(succ)(3)]H2O were measured.