Abstract
The structures of novel crystals of Rb5[(UO2)2(C2O4)4F]·2H2O (I) and Ba5[(UO2)2(C2O4)4F]2⋅22H2O (II) (CIF files CCDC nos. 2392480 (I) and 2392481 (II)) are studied by X‑ray diffraction (XRD). The uranyl-containing structural units are the binuclear complexes of the same composition [(UO2)2(C2O4)4F]5– but with different structures, which are described by the crystallochemical formulas \({{{\text{A}}}_{{\text{2}}}}{{{\text{T}}}^{{11}}}{\text{B}}_{{\text{3}}}^{{{\text{01}}}}{{{\text{M}}}^{{\text{1}}}}\) (I) and \({{{\text{A}}}_{{\text{2}}}}{\text{B}}_{{\text{4}}}^{{{\text{01}}}}{{{\text{M}}}^{{\text{2}}}}\) (II) (A = \({\text{UO}}_{{\text{2}}}^{{{\text{2 + }}}}\) , T11 or B01 = \({{{\text{C}}}_{{\text{2}}}}{\text{O}}_{{\text{4}}}^{{{\text{2}} - }}\) , M1 or M2 = F–). The complexes contain crystallographically nonequivalent U(VI) atoms, which are components of the uranyl ions and implement the pentagonal bipyramidal coordination. In compound I, the U(VI) atoms form coordination polyhedra UO2FO4 and UO2O5, and only UO2FO4 are formed in compound II. In both structures, the binuclear [(UO2)2(C2O4)4F]5– complexes are linked into a 3D framework due to coordination bonds R–O and R–F (R = Rb or Ba). The water molecules involved in the formation of a set of hydrogen bonds are localized in voids of the 3D framework. The IR spectroscopy results for compounds I and II are consistent with the XRD data.
