Cation-cation interaction in the double Th(IV)/Np(V) nitrate [H3O][Th2(NpO2)3(H2O)9(NO3)12]·2H2O

Abstract

A new double Th(IV)/Np(V) nitrate, [H3O][Th2(NpO2)3(H2O)9(NO3)12]·2H2O, was isolated in the crystalline form and studied by single crystal X-ray diffraction. Two independent Np atoms in the structure have the coordination polyhedra (CPs) in the form of pentagonal bipyramids with “yl” O atoms in the apical vertices. The equatorial plane of the Np(1) CP is constituted by the O atoms of the bidentate nitrate ion, two water molecules, and “yl” O atom of the adjacent Np(2)O2 group. The equatorial plane of the Np(2) CP is constituted by five water molecules disordered over two positions. The coordination surrounding of the Th4+ cation is formed by the O atoms of five bidentate nitrate ions disordered over two positions and the O atoms of two Np(1)O2 groups; the coordination number of the Th(1) atom is 12. Mixed-element cation-cation (CC) interaction of types NpO 2 + iTh4+ and NpO 2 + iNpO 2 + is observed in the structure. It leads to the formation of corrugated cationic networks. The CC interaction in the crystal is the main structure-forming factor. The hydroxonium ions [H3O]+, coordinated water molecules, and water molecules of crystallization are proton donors in hydrogen bonding. The three-dimensional network of hydrogen bonds additionally stabilizes the crystal packing.