Synthesis, crystal structure, and spectra of the Np(V) terephthalate [C(NH2)3]3[NpO2(C6H4(COO)2)2]·5H2O and An(VI) terephthalates [AnO2(C6H4(COO)2)] (An = U, Np, Pu)

Abstract

The structure and spectra of the Np(V) terephthalate [C(NH2)3]3[NpO2(C6H4(COO)2)2]·5H2O (I) and An(VI) terephthalates [AnO2(C6H4(COO)2)] (II), where An = U, Np, or Pu, were studied. The crystal structure of I is build of NpO2 + cations and terephthalate anions linked with each other in infinite anionic chains [NpO2(C6H4(COO)2)2]n 3−, with the water molecules and guanidinium cations arranged between them. The Np atom has the coordination surrounding in the form of a hexagonal bipyramid whose equatorial plane is formed by the O atoms of three [C6H4(COO)2]2− anions. There are two independent [C6H4(COO)2]2− anions in the structure. One of them is bidentate chelating, and the other is chelating and bridging, with both of its carboxylate groups bonded to the NpO2 + cations in the anionic chains in the bidentate fashion. Five crystallographically independent water molecules are localized in the structure of I. Together with the [C(NH2)3]+ cations, these water molecules form a three-dimensional system of hydrogen bonds. The crystal structure of II is built of neutral [AnO2(C6H4(COO)2)]n layers formed by the AnO2 2+ cations and terephthalate anions. The An(VI) atom has the coordination surrounding in the form of a tetragonal bipyramid whose equatorial plane is formed by the O atoms of four [C6H4(COO)2]2− anions. The IR and electronic absorption spectra of the compounds are presented.