mu-ita2:ita2-Peroxo-bis[nitratobis(pyrrolidine-2-one)dioxouranium(VI)]

In crystal structure of the title compound, {[UO2NO3(C4H7NO)2]2O2}, two UO22+ ions are connected by mu-ita2:ita2-O22–. An inversion center is located at the middle point of a O—O bond in the O2 moiety. As a result, the centrosymmetrically expanded dimeric structure is afforded. The O2 unit shows "side-on" coordination and connects two U, i.e., mu-ita2:ita2-O2. The bond lengths between U and the axial O are 1.78 Å (mean), indicating that oxidation state of U is exclusively 6+, i.e., UO22+. Furthermore, the O—O distance in the dioxy­gen moiety is 1.491 Å, which is typical of the peroxide, O22–. Each U atom is eight-coordinate in a hexagonal-bipyramidal geometry. The coordinating atoms of nitrate, pyrrolidine-2-one and mu-ita2:ita2-O22– are located on the equatorial plane, and form an irregular hexagon. The inter­molecular hydrogen bonds are found between N—H of 2-pyrrolidone and the coordinating O of the same ligand in the neighboring complex.