A Series of Cadmium(II) Coordination Polymers Synthesized at different pH Values

Synthesis, crystal structure, and two-dimension correlation infrared spectroscopy on two novel Pr carboxylic acid coordination polymers

Two new coordination polymers [Pr(PCPA)₃(H₂O)]_n1 and [Pr₂(PCPA)₆(H₂O)₃]_n·nH₂O 2(PCPA = p-chlorophenoxyacetic acid) have been synthesized under similar conditions by the hydrothermal method and characterized by single-crystal X-ray diffraction, elemental analyses, powder X-ray diffraction (PXRD) analysis, IR spectroscopy, two-dimensional correlation infrared spectroscopy(2D-IR COS) and ultraviolet-visible diffuse reflection integral spectroscopy (UV-Vis DRIS). 1 displays a 1D infinite chain, which is further linked by O/CH⋯O hydrogen bonds to form a 3D supra-molecular architecture. 2 shows a 2D layer structure, which is extended by CH⋯Cl hydrogen bonds generating a 3D network. Noteworthy, we also studied 2D-IR COS under the thermal perturbation to contribute to the development of theory. The 2D-IR correlation spectroscopy analysis is consistent with the analysis of structure and it is superior to 1D IR spectroscopy especially in the coordinated carboxyl group.

Infinite copper(II) coordination architectures from a resonative aminotriazine-derived tripodal ligand: synthesis, structures, and magnetic properties

The ligand 2,4,6-tris(2-picolylamino)-1,3,5-triazine (o-H3tpat) with essentially resonative structure and two copper(II)-based one-dimensional coordination chain structures, [Cu3Cl5(o-H2tpat)(H2O)]·MeOH·CH2Cl2 (1) and [Cu2(o-H2tpat)(H2O)(MeOH)(NO3)2](NO3)·3MeOH (2), with different structural patterns have been synthesized and characterized using single crystal X-ray diffraction analysis. For o-H3tpat, two crystalline forms showing different solid-state structural features are obtained from MeOH/Et2O (form I) and CH2Cl2/Et2O (form II), respectively. The o-H3tpat form I adopts an asymmetric-configured all-amino resonative tautomer with three cis-trans-trans-arranged pyridyl groups, whereas the o-H3tpat form II adopts also an identical resonative structure but where two of the three pyridyl groups are in a cis-manner and the third one is nearly coplanar with the central aminotriazine core. On the other hand, the designed tripodal ligand in both Cu(II)-complexes serves as a monoanion, o-H2tpat(-), which suits a propeller-configured all-imino resonative structure in 1 and a syn-anti-configured amino-imino-imino resonative structure in 2. These observations significantly indicate that the o-H3tpat ligand can self-adjust and interconvert its conformation via a possible structure transformation associated with proton-shift to adapt a change in the crystallization and self-assembly reaction systems. In the magnetic point of view, 1 is treated as repeated chains composed of infinite {Cu6Cl10} units wherein the hexanuclear unit is further decomposed to one {Cu(II)4Cl6} and two magnetically isolated {Cu(II)Cl2} subunits. Antiferromagnetic interactions are found for the Cu4 subunits (g = 2.33, 2J1 = -5.6 cm(-1), 2J2 = -8.6 cm(-1), 2J3 = -4.1 cm(-1), and J4 held to zero). For 2, it is considered as an infinite chain that composes of Cu2 units antiferromagnetically coupled (g = 2.03, 2J1 = -0.2 cm(-1)). The small antiferromagnetic exchange constants in both 1 and 2 suggest that the unpaired spins do not effectively interact through the tripodal o-H2tpat(-) ligands.

(1H-Benzimidazole-5-carb-oxy-lic acid-κN)(1H-benzimidazole-6-carb-oxy-lic acid-κN)silver(I) perchlorate

The reaction of 1H-benzimidazole-5-carb-oxy-lic acid with silver nitrate in the presence of perchloric acid under hydro-thermal conditions yielded the title complex, [Ag(C(8)H(6)N(2)O(2))(2)]ClO(4), which comprises of an [Ag(C(8)H(6)N(2)O(2))(2)] mononuclear cation and a perchlorate anion. The Ag(I) ion is coordinated by two N atoms from two different neutral 1H-benzimidazole-5-carb-oxy-lic acid ligands with an N-Ag-N bond angle of 163.21 (14)°, forming an [Ag(C(8)H(6)N(2)O(2))(2)] mononuclear cation. Although both ligands in the mononuclear cation are monodentate with one N atom coordinated to the metal ion, they are different: one is N(3) coordinated to the Ag (I) ion and the N(1) atom protonated, the other with the N(1) coordinated to the Ag (I) ion and the N(3) atom protonated (and thus formally a 1H-benzimidazole-6-carb-oxy-lic acid rather than a 1H-benzimidazole-5-carb-oxy-lic acid ligand). The planes of the two planar ligands are roughly perpendicular, making a dihedral angle of 84.97 (2)°. The packing of the ions is stablized by extensive O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, and by remote Ag⋯O inter-actions [3.002 (3), 3.581 (5) and 3.674 (5) Å].

catena-Poly[tris-(μ(2)-1H-benzimidazole-5-carboxyl-ato)europium(III)]

In the title one-dimensional coordination polymer, [Eu(C₈H₅N₂O₂)₃]_n, the Eu^III ion is eight-coordinated by the carboxyl­ate O atoms of six ligands in a distorted monocapped penta­gonal–bipyramidal geometry. The ligands link Eu^III ions, forming helical chains parallel to the c axis, with Eu⋯Eu separations of 4.0678 (11) Å. The chains are further inter­connected by N—H⋯N hydrogen bonds into a three-dimensional supra­molecular network. The crystal studied was a racemic twin, as suggested by the Flack parameter of 0.367 (14).

Supramolecular coordination assemblies constructed from multifunctional azole-containing carboxylic acids

This paper provides a brief review of recent progress in the field of metal coordination polymers assembled from azole-containing carboxylic acids and gives a diagrammatic summary of the diversity of topological structures in the resulting infinite metal-organic coordination networks (MOCNs). Azole-containing carboxylic acids are a favorable kind of multifunctional ligand to construct various metal complexes with isolated complexes and one, two and three dimensional structures, whose isolated complexes are not the focus of this review. An insight into the topology patterns of the infinite coordination polymers is provided. Analyzed topologies are compared with documented topologies and catalogued by the nature of nodes and connectivity pattern. New topologies which are not available from current topology databases are described and demonstrated graphically.