Novel networks of silver(I) cations assembled with 2,3-pyridinedicarboxylic acid: From 2D sheet to 3D network

A one-dimensional silver(I) coordination polymer based on 5-methyl-1,3,4-thiadiazol-2-amine and pyridine-2,3-dicarboxylate

The bifunctional pyridine-2,3-dicarboxylic acid (H2pdc) ligand has one N atom and four O atoms, which could bind more than one AgI centre with diverse binding modes. A novel infinite one-dimensional AgI coordination polymer, namely catena-poly[[silver(I)-(μ2-pyridine-2,3-dicarboxylato-κ2 N:O 3)-silver(I)-tris(μ2-5-methyl-1,3,4-thiodiazol-2-amine-κ2 N:N′)] monohydrate ethanol monosolvate], {[Ag2(C7H3NO4)(C3H5N3S)3]·H2O·C2H5OH} n , has been synthesized using H2pdc and 5-methyl-1,3,4-thiadiazol-2-amine (tda), and characterized by single-crystal X-ray diffraction. One AgI atom is located in a four-coordinated AgN4 tetrahedral geometry and the other AgI atom is in a tetrahedral AgN3O geometry. A dinuclear AgI cluster formed by three tda ligands with a paddelwheel configuration is bridged by the dianionic pdc2− ligand into a one-dimensional coordination polymer. Interchain N—H...O hydrogen bonds extend the one-dimensional chains into an undulating two-dimensional sheet. The sheets are further packed into a three-dimensional supramolecular framework by interchain N—H...O hydrogen bonds.

Structure of a dinuclear cadmium complex with 2,2'-bi-pyridine, monodentate nitrate and 3-carb-oxy-6-methyl-pyridine-2-carboxyl-ate ligands: intra-molecular carbon-yl(lone pair)⋯π(ring) and nitrate(π)⋯π(ring) inter-actions

The centrosymmetric dinuclear complex bis-(μ-3-carb-oxy-6-methyl-pyridine-2-carboxyl-ato)-κ(3) N,O (2):O (2);κ(3) O (2):N,O (2)-bis-[(2,2'-bi-pyridine-κ(2) N,N')(nitrato-κO)cadmium] methanol monosolvate, [Cd2(C8H6NO4)2(NO3)2(C10H8N2)2]·CH3OH, was isolated as colourless crystals from the reaction of Cd(NO3)2·4H2O, 6-methyl-pyridine-2,3-di-carb-oxy-lic acid (mepydcH2) and 2,2'-bi-pyridine in methanol. The asymmetric unit consists of a Cd(II) cation bound to a μ-κ(3) N,O (2):O (2)-mepydcH(-) anion, an N,N'-bidentate 2,2'-bi-pyridine group and an O-mono-dentate nitrate anion, and is completed with a methanol solvent mol-ecule at half-occupancy. The Cd complex unit is linked to its centrosymmetric image through a bridging mepydcH(-) carboxyl-ate O atom to complete the dinuclear complex mol-ecule. Despite a significant variation in the coordination angles, indicating a considerable departure from octa-hedral coordination geometry about the Cd(II) atom, the Cd-O and Cd-N distances in this complex are surprisingly similar. The crystal structure consists of O-H⋯O hydrogen-bonded chains parallel to a, further bound by C-H⋯O contacts along b to form planar two-dimensional arrays parallel to (001). The juxtaposed planes form inter-stitial columnar voids that are filled by the methanol solvent mol-ecules. These in turn inter-act with the complex mol-ecules to further stabilize the structure. A search in the literature showed that complexes with the mepydcH(-) ligand are rare and complexes reported previously with this ligand do not adopt the μ-κ(3) coordination mode found in the title compound.