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Single crystals of two new bimetallic oxalate compounds with the formula [ACr(C2O4)2(H2O)4]n(A= Li or Na), namelycatena-poly[[diaqualithium(I)]-μ-oxalato-κ4O1,O2:O1′,O2′-[diaquachromium(III)]-μ-oxalato-κ4O1,O2:O1′,O2′], (I), andcatena-poly[[diaquasodium(I)]-μ-oxalato-κ4O1,O2:O1′,O2′-[di-aquachromium(III)]-μ-oxalato-κ4O1,O2:O1′,O2′], (II), have been synthesized, characterized and their crystal structures elucidated by X-ray diffraction analysis and compared. The compounds crystallize in the monoclinic space groupC2/mfor (I) and in the triclinic space groupP\overline{1} for (II); however, they have somewhat similar features. In the asymmetric unit of (I), the Li and Cr atoms both have space-group-imposed 2/msite symmetry, while only half of the oxalate ligand is present and two independent water molecules lie on the mirror plane. The water O atoms around the Li atom are disordered over two equivalent positions separated by 0.54 (4) Å. In the asymmetric unit of (II), the atoms of one C2O42−ligand and two independent water molecules are in general positions, and the Na and Cr atoms lie on an inversion centre. Taking into account the symmetry sites of both metallic elements, the unit cells may be described as pseudo-face-centred monoclinic for (I) and as pseudo-centred triclinic for (II). Both crystal structures are comprised of one-dimensional chains of alternatingtrans-Cr(CO)4(H2O)2andtrans-A(CO)4(H2O)2units μ2-bridged by bis-chelating oxalate ligands. The resulting linear chains are parallel to the [101] direction for (I) and to the [11\overline{1}] direction for (II). Within the two coordination polymers, strong hydrogen bonds result in tetramericR44(12) synthons which link the metal chains, thus leading to two-dimensaional supramolecular architectures. The two structures differ from each other with respect to the symmetry relations inside the ligand, the role of electrostatic forces in the crystal structure and the molecular interactions of the hydrogen-bonded networks. Moreover, they exhibit the same UV–Vis pattern typical of a CrIIIcentrosymmetric geometry, while the IR absorption shows some differences due to the oxalate-ligand conformation. Polymers (I) and (II) are also distinguished by a different behaviours during the decomposition process, the precursor (I) leading to the oxide LiCrO2, while the residues of (II) consist of a mixture of sodium carbonate and CrIIIoxide.

The oxalate dianion is one of the most studied ligands and is capable of bridging two or more metal centres and creating inorganic polymers based on the assembly of metal polyhedra with a wide variety of one-, two- or three-dimensional extended structures. Yellow single crystals of a new mixed-metal oxalate, namelycatena-poly[[diaquasodium(I)]-μ-oxalato-κ4O1,O2:O1′,O2′-[diaquairon(III)]-μ-oxalato-κ4O1,O2:O1′,O2′], [NaFe(C2O4)2(H2O)4]n, have been synthesized and the crystal structure elucidated by X-ray diffraction analysis. The compound crystallizes in the noncentrosymmetric space groupI41(Z= 4). The asymmetric unit contains one NaIand one FeIIIatom lying on a fourfold symmetry axis, one μ2-bridging oxalate ligand and two aqua ligands. Each metal atom is surrounded by two chelating oxalate ligands and two equivalent water molecules. The structure consists of infinite one-dimensional chains of alternating FeO4(H2OW1)2and NaO4(H2OW2)2octahedra, bridged by oxalate ligands, parallel to the [100] and [010] directions, respectively. Because of thecisconfiguration and the μ2-coordination mode of the oxalate ligands, the chains run in a zigzag manner. This arrangement facilitates the formation of hydrogen bonds between neighbouring chains involving the H2O and oxalate ligands, leading to a two-dimensional framework. The structure of this new one-dimensional coordination polymer is shown to be unique among theAIMIII(C2O4)2(H2O)nseries. In addition, the absorption bands in the IR and UV–Visible regions and their assignments are in good agreement with the local symmetry of the oxalate ligand and the irregular environment of iron(III). The final product of the thermal decomposition of this precursor is the well-known ternary oxide NaFeO2.

Correlative studies of three oxalato-bridged polymers, obtained under hydrothermal conditions for the two isostructural compounds {Rb(HC2O4)(H2C2O4)(H2O)2}∞1, 1, {H3O(HC2O4)(H2C2O4).2H2O}∞1, 2, and by conventional synthetic method for {Rb(HC2O4)}∞3, 3, allowed the identification of H-bond patterns and structural dimensionality. Ferroïc domain structures are confirmed by electric measurements performed on 3. Although 2 resembles one oxalic acid sesquihydrate, its structure determination doesn’t display any kind of disorder and leads to recognition of a supramolecular network identical to hybrid s-block series, where moreover, unusual H3O+ and NH4+ similarity is brought out. Thermal behaviors show that 1D frameworks with extended H-bonds, whether with or without a metal center, have the same stability. Inversely, despite the dimensionalities, the same metallic intermediate and final compounds are obtained for the two Rb+ ferroïc materials.

High‐yielding syntheses of an unpublished series of 2‐thioxo‐imidazolidin‐4‐ones 6 bearing an N‐ethoxycarbonyl and amidyl moieties an N1 and C5, respectively, are reported. These derivatives were obtained by intramolecular cyclization of 3‐ethylhydrazinoacetate 3,4‐dihydro maleimides 4 in the presence of ethyl or phenylisothiocyanate 2 under neutral conditions.

In the title compound, [CaCs2(C2O4)2(H2O)4] n , the Ca(2+) ion, lying on a twofold rotation axis, is coordinated by four O atoms from two oxalate ligands and two bridging water mol-ecules in an octa-hedral geometry. The Cs(+) ion is coordinated by seven O atoms from six oxalate ligands, one bridging water and one terminal water mol-ecule. The oxalate ligand displays a scarce high denticity. The structure contains parallel chain units runnig along [10-1], formed by two edge-sharing Cs polyhedra connected by CsO9 polyhedra connected by a face-sharing CaO6 octahedron. These chains are further linked by the oxalate ligands to build up a three-dimensional framework. O-H⋯O hydrogen bonds involving the water mol-ecules and the carboxyl-ate O atoms enhance the extended structure.

High‐yielding syntheses of an unpublished series of 2‐thioxo‐imidazolidin‐4‐ones 6 bearing an N‐ethoxycarbonyl and amidyl moieties an N1 and C5, respectively, are reported. These derivatives were obtained by intramolecular cyclization of 3‐ethylhydrazinoacetate 3,4‐dihydro maleimides 4 in the presence of ethyl or phenylisothiocyanate 2 under neutral conditions.

In the title compound, [CaCs2(C2O4)2(H2O)4]n, the Ca2+ ion, lying on a twofold rotation axis, is coordinated by four O atoms from two oxalate ligands and two bridging water mol­ecules in an octa­hedral geometry. The Cs+ ion is coordinated by seven O atoms from six oxalate ligands, one bridging water and one terminal water mol­ecule. The oxalate ligand displays a scarce high denticity. The structure contains parallel chain units runnig along [10-1], formed by two edge-sharing Cs polyhedra connected by CsO9 polyhedra connected by a face-sharing CaO6 octahedron. These chains are further linked by the oxalate ligands to build up a three-dimensional framework. O—H⋯O hydrogen bonds involving the water mol­ecules and the carboxyl­ate O atoms enhance the extended structure.

We report here two bimetallic oxalate isomers with the same chemical formula [RbCr(C2O4)2(H2O)2], which have been synthesized respectively by a slow evaporation method at room temperature (compound I) [1], and under hydrothermal conditions (compound II) [2] with the same starting salts. Their structures show a several discrepancies, due probably to the synthetic conditions. Indeed, the compound I crystallizes in space group C2/m with the Cr, Rb atoms and one oxygen from water molecule lying on special positions. Moreover, the unique oxalate ligand forms a bridge between metal centers. The Cr atom is coordinated to 2 bidentate-chelating oxalates and 2 aqua ligands in a trans-conformation and any water molecule has been found around the 8-coordinated Rb atom, leading to a layered structure consists of alternating Rb and Cr polyhedra connected via the unique organic ligand. Whereas, the compound II crystallizes in space group P21/n, with all atoms located on general positions. Furthermore, two independent oxalato ligands exhibit different configurations, which one is pentadentate and the other is hexadentate with two different chelating modes. The very slightly distorted Cr octahedra consists of 2 bidentate-chelating oxalato ligands and 2 water molecules in a cis-conformation, while the alkali metal is surrounded by seven O atoms from oxalate groups, completed with two H2O molecules which are bridging the Cr and Rb polyhedra by one common edge. This results in the formation of three different chains of alternating edge- and vertex-shared polyhedra through oxalates groups and aqua ligands, running along the three space directions to build a three dimensional framework. These two compounds can be considered as supramolecular isomers [3].

The structure of Li3InF6 , at room-temperature (Ta), may be described into two unit cells 1 and 2 with P21/m symmetry [1]. All Li atoms are disordered since the octahedral Li atoms occupy fully sites with relatively high thermal parameters and the tedrahedral Li atoms are located on 2 partially occupied independent sites [2][3]. The structure of the low-temperature form is solved and refined at 100K in a superlattice. This latter leads to a cell identical with the cell 2 but with the a double c-axis. The mirror plane is replaced by a glide plane and the resulting space group is P21/c. The structure is closely related to that of the Ta form. The change is associated with shifts of all atoms (the largest shifts occured for the Li atoms), change in Li coordination number (6, 5 and 4). Significant differences are observed in some Li-F bond lenghs. The disorder of Li ions disappears at low temperature : the two original tetrahedral Li atoms occupy fully sites in the " superstructure" while the octahedral Li atoms show normal displacement parameters. It is notewortly that the octahedral Li atoms at room-temperature are rather oscillating between two positions but not statiscally disordered.