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The article describes the crystal structures of the compounds hemi(4,4'-bipyridinium) tris(5-chiorothiophene-2-carboxylato)dioxidouranate(VI) monohydrate and hemi[4,4'-(ethane-l,2-diyl)dipyridin-ium] tris(5-chlorothiophene-2-carboxylato)dioxidouranate(VI) monohydrate. The metal centres are connected by classical O--H-.O and N--H.O hydrogen bonds involving the coordinated ligands, the diprotonated organic linker cation and water molecules. The crystal structures are further supported by weak C--H.O and π-π stacking interactions.

In the crystal structures of the title compounds, C6H10N3O2+·C7H5O3−·H2O, (I), C6H10N3O2+·C7H4NO4−·H2O, (II), and C6H10N3O2+·C4H5O6−·C6H9N3O2, (III), the 2-amino-4,6-di­meth­oxy­pyrimidinium cation [abbreviated as (MeO)2-Hampy+] inter­acts with the carboxyl­ate group of the corresponding anion through a pair of nearly parallel N—H⋯O hydrogen bonds to form R22(8) ring motifs. In (I), the (MeO)2-Hampy+ cation is centrosymmetrically paired through a pair of N—H⋯N hydrogen bonds involving the 2-amino group and a ring N atom forming an R22(8) motif. In (II), inversion-related R22(8) motifs (amino–pyrimidine–carboxyl­ate motifs) are further bridged by N—H⋯O hydrogen bonds on either side forming a DDAA array of quadruple hydrogen bonds. This array is extended further on either side by Owater—H⋯Ometh­oxy hydrogen bonds, resulting in an array of six hydrogen bonds ( ADDAAD). The water mol­ecule plays a pivotal role, and five hydrogen-bonded fused rings are formed around the water mol­ecule. In (III), the carb­oxy group of the tartrate anion inter­acts with the ring N atom and 2-amino group of the neutral (MeO)2-ampy mol­ecule through N—H⋯O and O—H⋯N hydrogen bonds. There is also an intra­molecular O—H⋯O hydrogen bond in the tartrate anion. In all three crystal structures, C—H⋯O hydrogen bonds are observed. [ABSTRACT FROM AUTHOR]

In the title compounds, namely 2,4-diamino-5-[(3,4,5-trimethoxy­phenyl)methyl]­pyrimidin-1-ium pyridine-2-carboxyl­ate, C14H19N4O3+·C6H4NO2−, (I), and 2-amino-4,6-dimethyl­pyrimidin-1-ium pyridine-2-carboxyl­ate hemihydrate, C6H10N3+·C6H4NO2−·0.5H2O, (II), the trimethoprim and 2-amino-4,6-dimethyl­pyrimidin-1-ium cations are protonated at one of the pyrimidine N atoms. In (I), bifurcated hydrogen bonds are observed between a picolinate O atom, the protonated N atom and the 2-amino group; the graph-set designator is R21(6). The pyrimidine moieties of the trimethoprim cations are centrosymmetrically paired through a pair of N—H⋯N hydrogen bonds. In addition to the base pairing, one of the picolinate O atoms bridges the 2- and 4-amino groups on either side of the paired bases, resulting in a complementary DADA array. In (II), the carboxyl­ate group of the picolinate anion binds with the protonated pyrimidine N atom and the 2-amino group of the pyrimidine moiety through a pair of N—H⋯O hydrogen bonds, leading to the common ring motif R22(8). The water mol­ecule, which resides on a twofold rotation axis, bridges the carboxyl­ate group of the picolinate anion via O—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]