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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.

A new Ce(III)-malonate, growth by hetero-nuclearsynthesis, is investigated structurally at 100K. In this oxobridgedmaterial, the bi-anion does not allow the formation ofany synthons, but various bridges form connections displayingtypical sub-features. Cross-linked edge-shared CeO9 and CeO7(H2O)3 polyhedrons built up 3D packing accommodating twowater molecules embedded in extensive H-bonds. Stable at 25°C, it undergoes concomitant dehydration and decarboxylationsequences. By comparison, Ca(II)-hydrogenmalonate and acidicBa-malonate are also oxo-bridged polymers, but obtained differentlyand are much more stable. The former shows face-sharingbinuclear units, and synthons. The protonated ligands present inthe two alkaline-earth materials give peculiar decompositionprocess.Supporting information: TGA/ DTA/ DTTA curves of Cabasedcompound, TGA/ DTA/ DTTA curves of Ba-based compound,Coordination polyhedrons and fragment of 3D frameworkin Ce-malonate, Cross-linked layers in Ce-malonate, TheC(6) synthons in Ca-based compound, The bi-polyhedron stackingin Ca-based compound, Crystal data, collection proceduresand refinement for Ce-malonate, Selected geometric parametersin Ce coordination spheres, Hydrogen-bond geometry in Cemalonate,XRPD(X-ray powder diffraction) patterns of someintermediate and final TG products.

The title compound [Cu2(OOC-(CH2)6-COO)2] was synthesized and its crystal structure has been determined by single crystal X-ray diffraction methods. The complex crystallizes in the triclinic space group P-1 with a=5.1077(5) A, b=8.362(2) A, c=11.378(2) A, α=93.773(6)°, β=97.587(9)°, γ=90.493(’9)° and D cal=1.629 mg/m3 for Z=1. The structure is polymeric and consists of discrete anhydrous centrosymmetric binuclear units [Cu2(OOC-(CH2)6-COO)2]. The two copper(II) centres bridged by the suberate groups in a syn-syn conformation, are in pentacoordinated distorted square-pyramidal coordination environment, with an intramolecular Cu–Cu distance of 2.5793(10) A. Each binuclear unit, related to the next through μoxo bridges with a Cuμoxo–Cuμoxo separation of 3.2326(10)A, defines infinite chains of one-edge sharing CuO5 square pyramid.

The complex [Cu(OOC-(CH2)3-COO)(O=C(NH2)2]2·2H2O has been synthesized and characterized by X-ray crystallography. It crystallizes in the triclinic system P-1 with a = 8.003(2) A, b = 8.611(2) A, c = 8.620(2) A, α = 96.14(3)°, β = 116.66(2)°, γ = 105.66(4)° and V = 492.9(3) A3. The structure consists of discrete centrosymmetric binuclear units and water molecules. The Cu(II) ions adopt a square-pyramidal coordination with four oxygen atoms of four bridging carboxylate and one carbonyl oxygen of the monodentate urea ligand. There is a very strong interaction between the two copper centers in binuclear entities (Cu $$\cdots $$ Cu: 2.6266(15) A).

The title compound [BaCo(C3H2O4)2(H2O)4] was synthesized and its crystal structure was determined. The compound is orthorhombic, space group Pccn with a = 18.974(3) A, b = 6.783(2) A, c = 9.394(4) A. The structure is polymeric and consists of edge-sharing BaO8 polyhedra and CoO6 octahedra linked together by the malonate groups. The geometry around the Ba(II) centres is a slightly distorted square-antiprism with Ba–O distances ranging from 2.789(4) to 2.843(4) A. Around the Co(II) centres, the coordination forms a distorted octahedron with Co–O bonds between 2.040(3) and 2.238(4) A.

The structure of the title compound, [La(C5H6O4)(C5H7O4)(H2O)] . H2O, consists of dense layers formed by chains of one-edge-sharing LaO9 (H2O) polyhedra, linked together by the glutarate ligand. The three-dimensional polymeric structure, built up through connection of these layers by the hydrogen glutarate ligand, exhibits cavities accommodating a guest water molecule. The lanthanum ion is tenfold coordinated by four glutarates, acting as bridging-chelating carboxylate groups, by three hydrogen glutarates, three times monodentate, and by one water molecule. Its coordination polyhedron is highly distorted and intermediate between a bicapped dodecahedron and a tetracapped trigonal prism. Hydrogen bonding links the two water molecules and the framework built up from this polynuclear coordination polymer. A very short hydrogen bond, D ... A = 2.484 (3) Angstrom, links the protonated with the deprotonated acid groups in the hydrogen glutarate. [References: 12] 12

The title compound, [Ca(C3H3O4)2]n, has a polymeric structure, built up from noncentrosymmetric Ca2O12 face-sharing bipolyhedra, linked through the spacers of the ligands and forming a complex three-dimensional framework containing empty channels parallel to the [001] direction. The calcium ion lies on a 2 axis and is coordinated by eight O atoms from six hydrogen malonate ligands in a distorted bicapped dodeca­hedron. The tridentate ligand displays an η5-chelating coordination mode and forms both μ1,1 and μ1,3 bridges. In the extended network, the protonated O atom is involved in a strong hydrogen bond with a deprotonated O atom, forming an infinite array of the ligands. An M—O—M infinite linkage characteristic of metal–organic frameworks is prevented here by cage assembly around the metal.

The title compound, {[Ho2(C4H2O4)3(H2O)4]·3H2O}n, is an open framework formed of corrugated layers built up from noncentrosymmetric binuclear units extended through μ1,3-bridges to give inorganic chains linked in the [100] direction. Additional connections in the [011] direction, through the ligands as spacers, give a three-dimensional structure exhibiting one-dimensional channels occupied by three solvent water mol­ecules. The two independent water-coordinated HoIII atoms each have a nine-coordination mode via seven O atoms from five carboxyl­ate ligands in a tricapped trigonal prism and a monocapped square prism, respectively. Intra­layer hydrogen bonds involve aqua ligands acting as donors, with carboxyl­ate O atoms as acceptors.

The title compound, {[Yb2(C4H4O4)3(H2O)4]·6H2O}n, is a two-dimensional open-framework built up from centrosymmetric binuclear units developed along [100] through the spacers of four extended ligands, and inter­connected along [101] by two twisted ligands, forming a layered coordination polymer in the (010) plane embedding six uncoordinated water mol­ecules. The water-coordinated YbIII atom completes a nine-coordination mode via seven O atoms from four carboxyl­ate ligands, in a monocapped square anti­prism. One independent succinate ligand, located on an inversion center, is in a bidentate coordination mode, exhibiting an anti conformation. The second independent succinate ligand, in a gauche conformation, is bidentate and bridging–chelating, involving one triply ligating O atom displaying the longest Yb—O bond [2.598 (2) A]. In addition to inter­layer hydrogen bonds, intra­layer hydrogen bonds involve, as acceptors, carboxyl­ate O atoms which are in bidentate mode.

The title compound, [Sr(C5H7O4)2(H2O)2]n, crystallizes with an infinite polymeric network. The layered structure is built up from cross-linked infinite chains of one edge-sharing SrO7(H2O)2 polyhedra. One of the two crystallographically distinct ligands acts by its deprotonated group in bis-bridging-chelating mode and the second involves its two ends in bidentate and monodentate modes, respectively. The inorganic layers are pillared by methyl­ene spacers and form empty channels. Inter­layer hydrogen bonds involve mainly the protonated ends of the ligands as donors.

The title compound, {[Ce(C5H6O5)(H2O)4]Cl·2H2O}n, is a coordination polymer built up from binuclear units extending along [100] with the ligands as spacers. The complex polymers are held together by inter­layer hydrogen bonds involving the counter-ion and the solvent water mol­ecules embedded in the structure. The tetra­dentate glutarate dianion coordinates in a bridging–chelating mode, with one triply ligating O atom, and in a conventional carboxyl­ate bridge to the water-coordinated CeIII ion. In the centered cage assembly, two nine-coordinated CeIII ions are linked through six oxo bridges.

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.

catena-Poly[[aqualanthanum(III)]-μ-(8-carboxyoctanoato)-μ-octanedioato], [La(C 8 H 12 O 4 )(C 8 H 13 O 4 )(H 2 O)] n , is, to our knowledge, the first reported rare-earth complex containing a flexible long-chain ligand that crystallizes without water of crystallization. The layered polymeric structure is built from infinite chains of one-edge-sharing LaO 8 (H 2 O) polyhedra, connected through the carbon backbone chains of the ligands. The two chemically different ligands act in the same coordination modes, exhibiting chelating bonds and μ-1,1-bridging monodentate linkage, and adopting the same extended conformation. In the relatively limited hydrogen-bonding network, a very strong hydrogen bond between the deprotonated and protonated ligand ends stabilizes the framework.

International audience; The two three-dimensional oxo-bridged lanthanides \[Ln(2) (C4H2O4)(3) (H2O)(4)]center dot 3H(2)O\(3)(proportional to), with Ln=Ho3+ (1); Gd3+ (2), are isomorphous. They have layer-type structures built up from non-centrosymmetric dinuclear unit Ln(2)O(12)(H2O)(4), beside three lattice H2O molecules stabilizing the 3D open-framework. The building entities are linked through one classical syn-anti mu 2-carboxylato-(KO)-O-1:(KO)-O-1' bridge. Within the bi-polyhedra, two double mu 2-O';(KO)-O-2,O' bridges and a syn-syn classical one, support the magnetic measurements carried out on holmium compound indicating relatively weak anti-ferromagnetic interactions. The comparison with magnetic studies on the almost similar reported Gd(III) compound, suggested that concomitant antiferromagnetic and ferromagnetic properties could not be excluded. The two distinct thermal behaviors evidenced the higher metal-water bond strength with the smaller cation, and revealed the great supramolecular effects generated by hydrogen-bonding patterns.

The title compound, [La2(C3H2O4)3(H2O)4]·H2O, forms a layer-type polymeric structure. The layers, which contain infinite puckered four-membered La—O—La—O rings in a pseudo-ternary symmetry, are formed by the lanthanum and one independent malonate group. They are interconnected by the second independent malonate group, giving a three-dimensional framework in which wide channels accommodate one disordered water mol­ecule of crystallization. The La atom lies on a twofold axis and is ten-coordinated by eight O atoms from carboxyl­ate groups and two water mol­ecules. One malonate group is monodentate and triply bridging chelating, whilst the other is doubly monodentate. The extensive network of hydrogen bonds and bridge bonds observed in this structure enhances the structural stability. Despite some identical subfeatures, this structure is quite different from that observed in [La2(C3H2O4)3(H2O)3]·2H2O.

Two three-dimensional ionic open-framework rare-earth succinates have been synthesized. The lanthanum-based compound, 1, was obtained by the silica gel technique and the cerium-based compound, 2, via grown phase under reflux. These two coordination polymers are isostructural. Their layer-type structure is built up from infinite chains of one-edge-sharing polyhedra, discrete chloride ions and lattice water molecules. Strong hydrogen bonds cross link the two-dimensional substructure into a three-dimensional open-framework exhibiting wide channels parallel to [1 0 0] direction. The tetratopic succinate ligand, involved in a syn–anti bridging-chelating mode, links the metal atoms through μ2-oxo bridges. The thermal analysis confirms the high stability of the materials, probably due to the infinite metal–oxygen–metal arrays.

A hybrid framework material has been synthesized via a gel diffusive technique. Its X-ray single crystal structure has been determined at 120 K, in the tetragonal space group P42/mbc. The ligand is partially deprotonated giving interesting supramolecular bonding formed by hydrogenoglutarate anion, which can act as a building synthon. The layer-type polymeric structure is built up from isolated polyhedra linked via conventional carboxylate bridges and forming inorganic layers in the plane (001). Along [001], layers consisting of the methylene spacers of the ligands, complete the three-dimensional framework. The thermal analysis performed by TGA and DSC in air and under N2, respectively, revealed the high stability of the non-templated framework (up to 210 °C) and showed several phase transitions and one solid-state reaction detected by an exothermic peak at 500 °C.

In the title compound, [Ba{HOOC(C(6)H(4))(2)CO(2)}(2)(H(2)O)(2)] or [Ba(C(14)H(9)O(4))(2)(H(2)O)(2)], the Ba atoms are coordinated by nine O atoms, six from two 2'-carboxybiphenyl-2-carboxylate (Hbpdc(-)) ligands and three from three coordinated water molecules, resulting in the formation of face-sharing distorted monocapped square antiprisms. The Hbpdc(-) ligands bridge the Ba atoms to form a one-dimensional helical polymer, with a Ba...Ba distance across the chain of 4.1386 (17) A. Adjacent chains are parallel to each other. The two independent ligands are tetradentate and have the same coordination mode, exhibiting mu-oxo bridges and eta(8)-chelation. The crystal structure is further stabilized by hydrogen bonds within each chain.

Reaction of anhydrous binary fluorides LiF and InF3 in sealed platinum tube at the temperature gradient 680/670°C yields α-Li3InF6. This low-temperature form crystallizes in the space group P21/m with the cell dimensions a = 4.797(3) A, b = 8.679(1) A, c = 10.366(1) A and β = 90.90(1)°. The framework is built from InF6 and LiF6 octahedra, beside [Li2F6] bitetrahedra. The b-axis seems to be the backbone in the structural features. Running along it, zigzag anionic chains $$({\rm LiF}_4 )_n^{3n - }$$ , resulting from one—edge shared [Li2F10] groups and double files of single InF6 octahedra sharing common corners with [Li2F6], create an approximately hexagonally packed framework in the plane (1 0 0). The antiferroelectric behaviour evident from dielectric studies is confirmed by the antiparallel displacements of In and Li atoms from octahedral centres. This structure is mainly featured by the disorder observed in the lightest atoms. These atoms, which exhibit two kinds of environments, have been refined as two partially occupied sites for the tetrahedral one. Within the Li3MF6 compounds (M: trivalent or 3d element), this new structure reveals unexpected structural features, inducing its ferroic properties.

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.

In the title compound, [Co(C8H4O4)(C3H4N2)3(H2O)2]·H2O, thecisoidangles are in the range 85.59 (5)–93.56 (5)°, while two equaltransoidangles deviate significantly from the ideal linear angle, the third being almost linear. One carboxylate group is almost coplanar [1.23 (13)°] with the plane of its parent aromatic ring, although it has one O-atom donor involved in one coordination and one hydrogen bond as acceptor. The other carboxylate group does not coordinate and is rotated out of this plane with a torsional twist of 17.27 (20)°. The coordination neutral entity, based on aqua ligands and two cyclic co-ligands seems, at first sight, monomeric. Strongly tight,viaone intramolecular hydrogen bond between aqua and carboxylate O atoms, it brings out a quasi-planar six-membered ring around the CoIIatom, turning the CoN3O3coordination octahedron into a new building block. The rigidity of this feature associated with several hydrogen-bonded arrays yields an extended structure. In the resulting supramolecular packing, a binuclear hydrated CoIIassembly, built up from triple strands driven by different heterosynthons, embodies the synergy of coordination, covalent and hydrogen bonds.

The main strategy for preparing novel multifunctional materials is based on self-assembly method which employs polydentate organic ligands containing N- or O-donor as building blocks. In this context, those ligands like imidazole or carboxylate groups are of special interest due to their good coordination ability and diverse coordination modes [1]. As a part of our investigations of extended structures with mixed ligands, new complexes [Co(Hipht)2(Im)2(H2O)2] and [Co(Tpht)(Im)3(H2O)2].H2O were obtained by direct method, then characterized by IR spectroscopy, TG/ATD and X-ray crystallography. In the compound [Co(Hipht)2(Im)2(H2O)2], CoII is located on a symmetry center, surrounded by two aqua ligands, two hydrogeno-isophthalate ligands and two imidazole molecules, where all ligands adopt monodentate mode. The complex's geometry consist of two intermolecular N-H...O bonds (2,157 Å and 2,630 Å) formed by one H atom of imidazole ligand and oxygen atoms of acid molecules evolving along two directions, giving rise to R24 (16) synthons. The interplanar distance of 3,718 Å between two parallel imidazole rings reveals the existence of Π-Π interactions. In the [Co(Tpht)(Im)3(H2O)2].H2O [2], the Co cation exhibits an octahedral coordination sphere, with two aqua, three N-coordinated imidazole ligands and one terephthalato dianion. The three independent imidazole groups and the single terephtalate dianion, all unidentate participate respectively as donor and acceptor in strong to moderate hydrogen bonds, and allow the recognition of supramolecular dimensionality. The backbone of the architecture is the helical hydrogen-bonded ladder running along b axis, composed of alternating R44(10) and R33(8) heterosynthons, which are developed in bicyclic sheets. Non covalent interactions play a significant role in this class of materials [3], in fact, extended hydrogen bonds networks associated to Π-Π interactions lead to 3D supramolecular architecture for the two complexes.

By applying soft synthesis conditions, in presence of a mixture that contains malonic acid, (3 mmol), lanthanide salt CeCl3.7H2O (1 mmol), alkaline-earth hydroxide Ca(OH)2 (1 mmol), and at pH below 4, we have obtained single crystals of a novel rare-earth complex which includes the dianion [L2-], {[Ce2(C3H2O4)3(H2O)3].2H2O}.The given formula was deduced from the single crystal structure analysis. The asymmetric unit corresponds to chemical formula (Figure 1). This novel polymeric compound is a three-dimensional MOF, built up from cross-linked infinite chains of one-edge-shared CeO7(H2O)3 and CeO9 polyhedrons embedding solvent molecules. Each crystallographically different metal is connected to two neighbouring ones, through four μ2-oxo bridges, to form repeat four-membered typical Ce/O/Ce/O rings. The three independant ligands show different conformations of their end functional groups: syn-syn, syn-anti, anti-anti, giving explanation for the concomitant magnetic interactions and interesting magneto-structural data. These studies are still in progress. The TG curve shows five successive weight losses. The material begins losing weight directly upon starting the thermal gravimetric experiments. It is one of the more unstable lanthanide malonates known. The correlative thermal behaviour data and X-Ray structural sub-features of the novel Ce(III)-based MOF obtained, brought out the great supramolecular effects: decarboxylation process, crystalline, and thermal stabilities are much more related to the specific infinite hydrogen patterns, than the size, shape, and embedding capability of voids accommodated in the 3D packing.

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].