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Abstract  

New zinc complex compounds of general formula ZnL2,X2 {X=CI, Br; L=phenazone(phen), nicotinamide(nam)} were synthesized. The new compounds were characterized by elemental analysis, IR spectroscopy and DTA, TG/DTG methods. Thermal properties of the new compounds were investigated. It was found that nicotinamide, phenazone and ZnCl2 or ZnBr2 are released during the thermal decomposition of the compounds. Mass spectroscopy has been used for the determination of the thermal decomposition intermediate products.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Andrej Oriňák, Christina Crone, Alfred Benninghoven, Norbert Buschmann, Renáta Oriňáková, Heinrich Arlinghaus, and Martina Justinová

To characterize the stability and retention behavior of zinc carboxylato mixed-ligand complexes movement of the carboxylate ligand has been monitored by thin-layer chromatography coupled with time-of-flight secondary-ion mass spectrometry (TLC-TOF SIMS). Chromatography was performed on aluminum-backed RP-18 layers with a methanol-water mobile phase. After development the layers were coated with silver, from the vapor state, and the analytes were then eluted with a strongly polar mobile phase to a target channel. Analytes on targets defined by average R F values were analyzed by TOF SIMS. From preliminary analyses it was found that only zinc carboxylate complexes containing butyrate or isobutyrate anions as ligands could be detected and identified by TOF SIMS ( m/z 43, butyl, and m/z 87, butyrate). Further analysis was performed on the Zn(CH 3 CH 2 COO) 2 (tu) 2 complex only. It was found that butyrate anion moves in a spread chromatographic zone from the start of the layer. The maximum concentration of the carboxylate ligand was found at R F 0.33. From this position the intensity of the ions mentioned above decreases rapidly. This result confirms that the butyrate ligand of the Zn complex moves independently on an auxiliary (organic) ligand (thiourea) and partially on the zinc cation, confirming that the complex decomposes during chromatography.

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Abstract  

The eight solid complexes of zinc with L--methionine or L--histidine were prepared. The thermal decomposition processes of these complexes were determined by means of TG-DTG. The results show that their decomposition processes can be divided into three steps except for the complex Zn(Met)2 the decomposition of which is completed in one step. All the final products are ZnO.

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Abstract  

A new complex, diaquadi(1,2,4-triazol-5-one)zinc(II) ion nitrate formulated as {[Zn(TO)2(H2O)2](NO3)2}n (1) (1,2,4-triazole-5-one, abbreviated as: TO) was synthesized and characterized by elemental analysis, X-ray single crystal diffraction, infrared spectrum (IR), differential scanning calorimetry (DSC), thermogravimetric analysis and differential thermogravimetric analysis (TG-DTG). The X-ray structure analysis reveals that the complex is orthorhombic with space group Pbca and unit-cell parameters a=6.9504(2) �; b=10.6473(3) �; c=17.8555(5) �. Based on the result of thermal analysis, the thermal decomposition process of the compound was derived. From measurement of the enthalpy of solution in water in 298.15 K, the standard molar enthalpy of solution of lignand TO and the complex were determined as 15.43�0.18 and 52.64�0.42 kJ mol−1, respectively. In addition, the standard molar enthalpy of formation of TO(aq) was calculated as −126.97�0.72 kJ mol−1.

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Abstract  

The zinc(II) complex with nicotinamide (ncam) was prepared and investigated by single-crystal X-ray diffraction, infrared spectrum (FTIR), conductivity and thermal analysis techniques. The formula of complex is [Zn(ncam)2(H2O)4](NO3)2·2H2O. The nicotinamide molecule has three following donor sites: pyridine ring nitrogen, aminonitrogen and carbonyl group oxygen. In this monomeric complex, the Zn(II) ion is six-coordinated by two pyridine ring N atoms and four water O atoms in a slightly distorted octahedral arrangement. In the crystal structure, intermolecular O-H…O and N-H…O hydrogen bonds link the molecules to form a supramolecular structure. The complex is stable up to 323 and above 360 K it dehydrates in one step losing six water molecules. The dehydration proceeds in the range of 360–438 K, and its enthalpy value is equal to 62.6±1.5 kJ mol−1.

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Journal of Flow Chemistry
Authors: Levi Zane Miller, Jeremy J. Hrudka, Yuta R. Naro, Michael Haaf, Michael Shatruk, and D. Tyler McQuade

A new method involving rapid flow of ligand solutions through a cartridge loaded with crystalline sodium diethylzinc hydride and subsequent isolation of three Zn—hydroxyquinoline complexes is described. The rapid-flow approach allowed the pyrophoric starting material to be used outside of the glovebox atmosphere and enabled fast mixing with ligand solutions for zinc complexation in seconds. The identity of all complexes was established by proton (1H) and carbon (13C) nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction.

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Abstract  

The enthalpies of solution in water of L--methionine and its zinc complexes Zn(Met)Cl2, Zn(Met)2Cl2·2H2O, Zn(Met)(NO3)2·1/2H2O, Zn(Met)3(NO3)2·H2O and Zn(Met)SO4·H2O have been measured at 298.15 K. The standard enthalpy of formation of met(aq) has been calculated. The experimental results have been discussed.

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Abstract  

Some new hydrazinium transition metal sulfite dihydrate complexes of the formula (N2H5)2M(SO3)2(H2O)2 where M=Fe, Co, Ni, Cu and Zn have been prepared and characterized by hydrazine and metal analyses, magnetic studies, electronic and infrared spectra and thermal analysis. The magnetic studies coupled with electronic spectra of iron, cobalt, nickel and copper complexes indicate their high spin octahedral nature. However the zinc complex is diamagnetic and show only the charge transfer transition. The infrared spectra shows that both the hydrazinium ions are coordinated to the metal ions, the sulfite ions are present as bidentate ligand. The simultaneous TG-DTA of these complexes were investigated in air and nitrogen atmospheres. In air, cobalt, nickel and zinc complexes give respective metal sulfate as the final residue while iron and copper complexes give the mixture of respective metal oxide and sulfate as the decomposition product. In nitrogen atmosphere respective metal sulfites are formed as the end residue.

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Abstract  

The nature and composition of complexes formed by the reaction of Fe(III), Cr(III), Zn(II), and Co(II) with potassium pentacyanonitrosyl manganate K3 [Mn(CN)5NO] has been investigated by radiometric method. The metals form 1∶1 complexes with K3 [Mn(CN)5NO], the optimum pH for maximum precipitation being 3.6 for Fe(III), 7.3 for Cr(III), 5.4 for Zn(II), and 8.3 for Co(II). The solubility of the complexes as computed from activity at maximum precipitation point follows the order: chromium complex > iron complex > cobalt complex > zinc complex. The radiometric titration curves also show the formation of colloidal precipitates with dilute Zn(II) solutions.

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Abstract  

Effect of γ-radiation on non-isothermal decomposition kinetics of bis(diethylene triamine)cobalt(II) nitrate and bis(diethylene triamine)zinc(II) nitrate have been studied in nitrogen atmosphere at a heating rate of 10 °C/minute. The data were analyzed by Coats- Redfern, Freeman-Caroll and Horowitz-Metzeger methods. The result showed that irradiation enhanced thermal decomposition in both the complexes. Activation energy and associated kinetic parameters are lowered upon irradiation and the extent of lowering is higher in cobalt complex compared to zinc complex. Order of the reaction for each step was found to be unity. The mechanism for deamination and decomposition is controlled by R2 function except for the deamination of unirradiated cobalt complex where the process is governed by R3 function.

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