Syntheses and characterization of Zn(II), Cd(II) and Hg(II) complexes with 5-methyl-1-(2′-pyridyl)pyrazole-3-carboxamide (MP y P z CA) ligand

From the reaction between Zn(II), Cd(II) and Hg(II) with 5-methyl-1-(2′-pyridyl)pyrazole-3-carboxamide (MP _y P _z CA) in ethanol, the complexes [Zn(MP _y P _z CA)₂(NO₃)]⁺ [(NO₃)_0.60(ClO₄)_0.40]^?·H₂O, Cd(MP _y P _z CA)₂Cl₂ and Hg(MP _y P _z CA)(SCN)₂ were obtained. These compounds have been characterized by IR and CHN analyses. The structure of [Zn(MP _y P _z CA)₂NO₃]⁺[(NO₃)_0.60(ClO₄)_0.40]^?·H₂O has been solved by X-ray crystallography. The coordination environment around the Zn(II) may be described as a trigonal bipyramid in which the ligands are both bidentate, but coordinated differently. The coordination sphere is completed with the oxygen atom of a nitrate anion as a unidentate ligand.     

Ionothermal syntheses and characterization of 2-D coordination polymers with 4-(1H-imidazol-1-yl) benzoic acid

4-(1H-imidazol-1-yl) benzoic acid and its coordination polymers [M(IBA)Cl] _n (M?=?Zn (1) and Co (2)) have been synthesized. Compounds 1 and 2 were obtained under ionothermal conditions and possess a 2-D laminar [M(IBA)] _n layer based on M₂(CO₂)₂ building blocks with coordinated chloride completing tetrahedral coordination of the metal. Compound 1 exhibits two photoluminescence emission peaks at 410 and 510?nm. The low-energy emission can be attributed to ligand-centered transition and the high-energy band can be assigned to ligand-to-metal charge transfer between the aromatic systems of the organic ligands and the 4s orbitals of Zn(II). The role of the ionic liquid in ionothermal synthesis and crystallization of 1 and 2 are briefly discussed.     

Synthesis,crystal structure,and properties of a new zinc coordination polymer [Zn(PMP)2Cl] n

A new coordination polymer [Zn(PMP)₂Cl] _n (PMP = 1-phenyl-3-methyl-5-pyrazolone) has been prepared by the reaction of zinc chloride and PMP, and characterized by elemental analysis, IR, UV, and fluorescence spectra, TG/DTA, and electrochemical analysis. Single crystal X-ray diffraction revealed that the complex is monoclinic, space group P 2(1)/n, with a = 10.850(17), b = 17.578(2), c = 10.997(18) Å, β = 104.999(3)°, V = 2025.8(5) ų, Z = 4, D_c = 1.470 mg m^?3, F(000) = 920, goodness-of-fit = 0.905, and R ₁ = 0.0441. The complex is a 1-D coordination polymer, and the coordination geometry of Zn(II) is a distorted tetrahedron.     

A new three-connected metal-organic coordination polymer with helical motifs: synthesis,crystal structure and photoluminescence

An interesting metal-organic network with helical motifs, {[Zn₂(mpdc)₂(bpy)(H₂O)₂]?·?2H₂O} (1, mpdc?=?2,6-dimethyl pyrdine-3,5-dicarboxylate), was synthesized under hydrothermal conditions, and characterized. Single-crystal X-ray structural analysis indicates that the title compound crystallizes in a monoclinic lattice, P2(1)/c with a?=?7.811(2), b?=?12.324(3), c?=?15.794(4)A, β?=?98.206(4)°, Z?=?2, V?=?1504.8(7)?ų, D _c?=?1.704?Mg?m^?3, F(000)?=?816, R ₁?=?0.0379, wR ₂?=?0.0807. In the structure of 1 the helical strands composed of [Zn(mpdc)(H₂O)] array in an interlacing fashion, and trap solvated water molecules to assemble a novel supramolecular network. Compound 1 exhibits strong photoluminescence in the solid state at room temperature.     

Synthesis,spectroscopy, thermodynamics and structure of [ZnCl2 (η3-dpktch)] (η3-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

When dpktch was reacted with ZnCl₂ in refluxing acetonitrile in air [ZnCl₂(η³-dpktch)] was isolated in good yield. Infrared spectra suggest weaker binding of dpktch in [ZnCl₂(η³-dpktch)] than in [CdCl₂(η³-dpktch)]. ¹H-NMR studies in non-aqueous media show that [ZnCl₂(η³-dpktch)] is sensitive to changes in its environment and exchanges its amide proton. Electronic absorption spectral measurements confirmed the sensitivity of [ZnCl₂(η³-dpktch)] to changes in its surroundings and show inter-conversion between two intra-ligand-charge-transfer transitions (ILCT) at 330?±?2 nm and 404?±?2 associated with [ZnCl₂(η³-dpktch)] and its conjugate base. Thermo-optical measurements in non-aqueous dmf and dmso show facile inter-conversion between [ZnCl₂(η³-dpktch)] and its conjugate base, respectively. Also, it is shown that protonation of dmf by [ZnCl₂(η³-dpktch)] is exothermic (standard enthalpy of protonation ΔH^θ ?=??40.7?±?1.8 kJ mol^?1), but endothermic for dmso (ΔH^θ ?=?+8.3?±?1.5 kJ mol^?1). Chemical stimuli in concentrations as low as 5.0?×?10^?7 M can be detected and determined using [ZnCl₂(η³-dpktch)] in non-aqueous media. X-ray crystallographic studies on a monoclinic, P2₁/n single crystal of [ZnCl₂(η³-dpktch)] confirmed the N,N,O-coordination of dpktch and revealed interdigitated units of [ZnCl₂(η³-dpktch)] connected via a web of hydrogen bonds.     

Three polynuclear complexes with bridging triazole ligand: crystal structures

Three polynuclear clusters, [Cu₄L₈](ClO₄)₄·4H₂O (1), [Zn₃L₆(H₂O)₆](ClO₄)₆·6H₂O (2), and [Mn₃L₆(CH₃OH)₆](ClO₄)₆·4.5H₂O (3) (L?=?4-(4-hydroxyphenyl)-1,2,4-triazole), obtained by the reactions of M(ClO₄)₂·6H₂O with L have been isolated and structurally characterized. Complex 1 featured a tetranuclear Cu(I) structure. Both 2 and 3 are linear hexapositive trimers linked by three N1,N2–1,2,4-triazole ligands to the divalent central and terminal metal ions. Furthermore, the luminescence properties of 2 were investigated at room temperature in the solid state.     

Syntheses and structures of 2-bromo-4-chloro-6- (cyclopropyliminomethyl)phenol and its zinc(II) complex

A new Schiff-base ligand 2-bromo-4-chloro-6-(cyclopropyliminomethyl)phenol and its zinc(II) complex have been synthesized and characterized by elemental analyses, infrared spectroscopy, ¹H NMR, ¹³C NMR, and single crystal X-ray determinations. The ligand and the complex crystallized in the space groups Pnma and P2₁/c, respectively. In the complex, the Zn atom is four-coordinate tetrahedral coordination with two imine N and two phenolate O atoms from two Schiff-base ligands. The bond lengths related to the donor atoms in the complex are different from those in the ligand. The coordination of the ligand to the zinc also was supported by IR spectra.     

Synthesis and Characterization of Ni(II), Cu(II), Zn(II) and Cd(II) Complexes of a New Vic-Dioxime Ligand

In this study, 1,2-dihydroxyimino-3,7-di-aza-9,10-O-α-methyl benzal decane (LH₂) was synthesized starting from 1,2-O-α-methyl benzal-4-aza-7-amino heptane (RNH₂) and antichloroglyoxime. With this ligand, complexes were synthesized using Ni(II) and Cu(II) salts with a metal:ligand ratio of 1:2. However, the reaction of the ligand with salts of Zn(II) and Cd(II) gave products with metal:ligand ratio of 1:1. Structures of the ligand and its complexes are proposed based on elemental analyses, IR, ¹³C- and ¹H-NMR spectra, magnetic susceptibility measurements and thermogravimetric analyses (TGA).     

cis-bis(Saccharinato)cobalt(II) and -zinc(II) complexes with 2-dimethylaminoethanol: syntheses,crystal structures,spectroscopic and thermal studies

2-Dimethylaminoethanol (dmea) reacted with tetraaqua-bis(saccharinato)cobalt(II) and -zinc(II) in n-butanol to yield the new complexes cis-[Co(sac)₂(dmea)₂] (1), and cis-[Zn(sac)₂(dmea)₂] (2) (sac?=?saccharinate). The complexes were characterized by elemental analyses, IR spectroscopy, DTA-TG and X-ray crystallography. Both complexes are isomorphous and crystallize in the monoclinic space group P2₁/c. The cobalt(II) and zinc(II) ions are coordinated by two neutral dmea ligands and two sac anions in a distorted octahedral environment. The dmea ligand acts as a bidentate N, O donor through the amine N and hydroxyl O atoms, while the sac ligand exhibits non-equivalent coordination, behaving as an ambidentate ligand; one coordinates to the metal via the carbonyl oxygen atom, while the other is N-bonded. The packing of the molecules in the crystals of both complexes is achieved by aromatic π(sac)–π(sac) stacking interactions, C–H?·?π interactions and weak intermolecular C–H?·?O hydrogen bonds involving the methyl groups of dmea and the sulfonyl oxygen atoms of the sac ligands. IR and UV spectra and thermal analysis are in agreement with the crystal structures.     

New heterometallic coordination polymers based on zinc(II) complexes with Schiff-base ligands and dicyanometallates: synthesis,crystal structures,and luminescent properties

Four new d¹⁰ heterometallic coordination polymers have been obtained using three Schiff-base ligands, zinc(II) nitrate, and dicyanometallates: ₁^∞[{Zn₃(Salen)₂}{μ-Au(CN)₂}₂] (1); ₁^∞[Zn(Saldmen){μ-Ag(CN)₂}]·2H₂O (2); ₁^∞[Zn(Salampy){μ-Ag(CN)₂}] (3); ₁^∞[Zn(Salampy){μ-Au(CN)₂}] (4). The Schiff bases are obtained from condensation of salicylaldehyde with ethylenediamine (H₂Salen); N,N-dimethyl-ethylenediamine (HSaldmen) and, respectively, 2-aminomethyl-pyridine (HSalampy). The dicyanometallates are K[Ag(CN)₂] and K[Au(CN)₂]. The compounds were characterized by X-ray single-crystal diffraction, infrared spectroscopy, UV–vis spectroscopy, and elemental analysis. In compound 1, the homotrimetallic units, {Zn₃(salen)₂}²⁺, are connected by two [Au(CN)₂]^? bridges, forming a 1-D double chain. In compounds 2–4, the crystal structures show polymeric zigzag chains generated by the mononuclear zinc(II) nodes and [M(CN)₂]^? spacers. The luminescence properties of the new heterometallic polymers have also been investigated.