Cover illustration: The packing in the unit cell of 5-[1-(benzylamino)ethylidene]-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione, with C-HO hydrogen bonds shown as dashed lines. See da Silva, Ribiero, Lima, Wardell, Skakle, Low & Glidewell [Acta Cryst. (2005), C61, o15-o20].
The title compound contains individual [UO2(O2)(CO3)2]4− ions in which the U atom is coordinated to two trans-axial O atoms and six O atoms in the equatorial plane, forming distorted hexagonal bipyramids.
Doubling of the cubic lattice of the title compound relative to the rocksalt-type phase reported previously is due to ordering of N and F atoms along all three cell axes. Residual electron density at an interstitial tetrahedral site was refined as a Frenkel defect of F atoms.