Abstract: | Two new malonate-containing uranyl complexes with carbamide of the formulas UO2(C3H2O4)(Urea)2] (I) and UO2(C3H2O4)(Urea)3] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula UO2(C2O4)(Urea)3] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains UO2(C3H2O4)(Urea)2]∞ belonging to the crystal-chemical group AT11M21 (A = UO22+, T11 = C3H2O42-, M1 = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes UO2(L)(Urea)3], where L = C3H2O42- or C2O42-, belonging to the crystal-chemical group AB01M31 (A = UO22+, B01 = C3H2O42- or C2O42-, M1 = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered. |