Synthesis, crystal structures and magnetic properties of three new 4-cyanobenzoate complexes

Crystal structure and Hirshfeld surface analysis of two iHOFs based on CH...NC hydrogen bonding

Two ionic hydrogen-bonded organic frameworks (iHOFs) assembled from 4-cyano-N-(4-cyanobenzyl)pyridinium, have been crystallized with Br- and antimony(III) pentabromide, [SbBr5]2-, as counter-ions and characterized. These are 4-cyano-N-(4-cyanobenzyl)pyridinium bromide, C14H10N3+·Br-, and bis[4-cyano-N-(4-cyanobenzyl)pyridinium] antimony(III) pentabromide, (C14H10N3)2[SbBr5]. The CH...NC interactions induced by templating anions construct disparate frameworks. Hirshfeld surface analysis indicated that these crystals exhibit two types of hydrogen-bonding interactions, specifically CH...NC and CH...Br. Consecutive reverse-parallel CH...NC hydrogen-bonding interactions in these crystals induced the formation of a large number of CH...NC bonds which exhibit both cis and trans configurations.

Synthesis and crystal structure of a cadmium(II) coordination polymer based on 4,4'-(1H-1,2,4-triazole-3,5-di-yl)dibenzoate

The asymmetric unit of the title compound, catena-poly[[[aqua-bis-(pyridine-κN)cadmium(II)]-μ2-4,4'-(1H-1,2,4-triazole-3,5-di-yl)dibenzoato-κ4 O,O':O'',O'''] 4.5-hydrate], {[Cd(C16H9N3O4)(C5H5N)2(H2O)]·4.5H2O}n or {[Cd(bct)(py)2(H2O)]·4.5H2O}n (I), consists of a Cd2+ cation coordinated to one bct2- carboxyl-ate dianion, two mol-ecules of pyridine and a water mol-ecule as well as four and a half water mol-ecules of crystallization. The metal ion in I possesses a penta-gonal-bipyramidal environment with the four O atoms of the two bidentately coordinated carboxyl-ate groups and the N atom of a pyridine mol-ecule forming the O4N equatorial plane, while the N atom of another pyridine ligand and the O atom of the water mol-ecule occupy the axial positions. The bct2- bridging ligand connects two metal ions via its carb-oxy-lic groups, resulting in the formation of a parallel linear polymeric chain running along the [11] direction. The coordinated water mol-ecule of one chain forms a strong O-H⋯O hydrogen bond with the carboxyl-ate O atom of a neighboring chain, leading to the formation of double chains with a closest distance of 5.425 (7) Å between the cadmium ions belonging to different chains. Aromatic π-π stacking inter-actions between the benzene fragments of the anions as well as between the coordinated pyridine mol-ecules belonging to different chains results in the formation of sheets oriented parallel to the (01) plane. As a result of hydrogen-bonding inter-actions involving the water mol-ecules of crystallization, the sheets are joined together in a three-dimensional network.

Tetrathiafulvalene-tetracarboxylate: an intriguing building block with versatility in coordination structures and redox properties

The synthesis of the transition metal coordination polymers containing a tetrathiafulvalene (TTF) moiety substituted with a tetracarboxylate group of the formulas [Mn(L)(0.5)(phen)(H(2)O)(2)](n).nH(2)O (1), [Mn(L)(0.5)(bpy)](n).nH(2)O (2), [Mn(L)(0.5)(bpy)(CH(3)OH)](n).2nH(2)O (3), and [Cu(L)(0.5)(bpy)(DMF)](n).n(DMF) (4) (L(4-) = TTF-tetracarboxylate; phen = 1,10-phenanthroline; bpy = 2,2'-bipyridine) is reported. Complex 1 is a two-dimensional (2-D) coordination polymer constructed of infinite carboxylate bridged Mn(II) chains and TTF moiety linkages. Complex 2 possesses a 3-D polymeric structure formed by infinite -Mn-(O-C-O)(2)-Mn- bridged one-dimensional (1-D) chains, which are further coordinated by TTF-tetracarboxylate ligands of two different orientations. Both complexes 3 and 4 show 1-D extended chain structures but are constituted by different dinuclear metal(II) units with a -Mn-(O-C-O)(2)-Mn- bridge in 3 and a -Cu-(O)(2)-Cu- bridge in 4. Electrochemical study of the solid-state compounds attests to the redox activity of the coordination system. Magnetic investigations reveal the existence of antiferromagnetic interactions between magnetic centers in complexes 3 and 4, while in 1, the paramagnetic metallic centers are isolated, in agreement with the solid-state structure.

New Copper(II) and Nickel(II) Complexes with Bifunctional Tetrazolate-5-carboxylate Ligands: Syntheses, Crystal Structures, and Magnetic Properties

Four new complexes with bifunctional tetrazolate-5-carboxylate ligands of 1H-tetrazole-5-formic acid (H2tzf) and 1H-tetrazole-5-acetic acid (H2tza), namely two dinuclear [M(tzf)(H2O)3]2·2H2O (M = Cu 1, Ni 2) and two mononuclear [Cu(tzf)(2,2′-bipy)2]·5H2O 3 and Cu(tza)(2,2′-bipy)H2O 4, were prepared and structurally characterized by single-crystal X-ray diffraction. Two different coordination modes of tetrazolate-5-carboxylate ligands exist: a tridentate N,O-chelated-N-bridged mode in 1 and 2, and a bidentate N,O-chelated mode in 3 and 4, which was first observed for the tetrazolate-5-carboxylate complexes. Extensive hydrogen bonds play an important role in the construction of the supramolecular network. Variable-temperature magnetic susceptibility data show the presence of antiferromagnetic interactions in 1 and 2. The thermogravimetric analyses of complexes 1–4 are also discussed.