Synthesis and X-ray crystallography of single crystals of [Mg(H2O)(6)][AnO(2)(C2H5COO)(3)](2), where An = U (I), Np (II), or Pu (III), are reported. Compounds IIII are isostructural and crystallize in the trigonal crystal system. The structures of IIII are built of hydrated magnesium cations [Mg(H2O)(6)](2+) and mononuclear [AnO(2)(C2H5COO)(3)](-) complexes, which belong to the AB013 crystallochemical group of uranyl complexes (A = AnO(2)(2+), B-01 = C2H5COO ). Peculiarities of intermolecular interactions in the structures of [Mg(H2O)(6)][UO2(L)(3)](2) complexes depending on the carboxylate ion L (acetate, propionate, or n-butyrate) are investigated using the method of molecular VoronoiDirichlet polyhedra. Actinide contraction in the series of U(VI)Np(VI)Pu(VI) in compounds IIII is reflected in a decrease in the mean An?O bond lengths and in the volume and sphericity degree of VoronoiDirichlet polyhedra of An atoms.