μ-η2:η2-Peroxido-bis­nitratodioxido­bis(pyrrolidin-2-one)uranium(VI)

摘要

In the crystal structure of the title compound, [U2(NO3)2O4(O2)(C4H7NO)4], two UO2 ²⁺ ions are connected by a μ-η²:η²-O2 unit. The O2 unit shows ‘side-on’ coordination to both U atoms. An inversion center is located at the midpoint of the O—O bond in the O2 unit, affording a centrosymmetrically expanded dimeric structure. The U—O(axial) bond lengths are 1.777 (4) Å and 1.784 (4) Å, indicating that the oxidation state of U is exclusively 6+, i.e., UO2 ²⁺. Furthermore, the O—O distance is 1.492 (8) Å, which is typical of peroxide, O2 ^2–. The U atom is eight-coordinated in a hexa­gonal-bipyramidal geometry. The coordinating atoms of the nitrate and pyrrolidine-2-one ligands and the μ-η²:η²-O2 ^2– unit are located in the equatorial plane and form an irregular hexa­gon. An inter­molecular hydrogen bond is found between N—H of the pyrrolidine-2-one ligand and the coordinating O of the same ligand in a neighboring complex. A second inter­molecular hydrogen bond is found between the N—H of the other pyrrolidine-2-one ligand and one of the uranyl oxido atoms.