N,N′-Dimethylthiourea Complees of Zinc,Cadmium(II), and Mercury(II)

N,N′-Dimethylthioharnstoff-Komplexe des Zn, Cd^II und Hg^II Komplexe des N,N′-Dimethylthioharnstoffs (DMTU) mit Zn–, Cd^II-und Hg^II-Halogeniden des Typs M(DMTU)₂X₂ und [HgDMTUX₂]₂ (X ? Cl, Br, J) wurden dargestellt und IR-spektroskopisch (4000-60cm^?1) sowie durch Leitfähigkeitsmessungen untersucht. Die Molekulargewichte einiger dieser Komplet in Nitrobenzol werden angegeben. Die 1:2-Komplexe Zn(DMTU)₂X₂, Cd(DMTU)₂X₂ (X ? Cl, Br, J) und Hg(DMTU)₂J₂ sind tetraedrisch, während die Komplexe Hg(DMTU)₂X₂ (X ? Cl, Br) eine pseudooktaedrische Halogen-verbrückte Konfiguration zu haben scheinen. Die 1:1 Hg^II-Komplexe [HgDMTUX₂]₂ (X ? Cl, Br, J) haben im festen Zustand eine dimere tetraedrische Halogen-verbrückte Struktur. In allen diesen Komplexen ist N,N′-Dimethylthioharnstoff über den Schwefel am Metall gebunden.     

Stability,Formation and Dissociation Kinetics of the Pentacoordinate Ni2+ and CO2+ Complexes with 1,5-Diazacyclooctane-N,N′-diacetic Acid

The stability constants of the Ni²⁺ and Co²⁺ complexes with 1,5-diazacyclooctane-N,N′-diacetic acid (H₂DACODA) have been determined potentiometrically in 0.5M KNO₃ at 25°. Only M(DACODA) and M(DACODA)OH^? were observed. In addition the formation and dissociation kinetics of the pentacoordinate complexes M(DACODA) has been studied in aqueous solution using a stopped-flow technique. Formation follows the rate law v_f = k_f [M²⁺] [HDACODA^?]/[H⁺], which can be interpreted as a bimolecular process either between M²⁺ and DACODA^2? (k) or between MOH⁺ and HDACODA^? (k). The second order rate constants k are much higher than those expected from water exchange and can only be explained by a strong internal conjugate base effect. In the limiting case, however, this is equivalent to the second possible explanation, which assumes MOH⁺ and HDACODA^? as reactive species. The dissociation rate is given by v_d = (k^ML + k [H⁺]) · [M(DACODA)].     

Structural Variety of Cobalt(II), Nickel(II), Zinc(II), and Cadmium(II) Complexes with 4,4′‐Azopyridine: Synthesis,Structure and Luminescence Properties

Self‐assembled bi‐ and polymetallic complexes of Co^II, Ni^II, Zn^II, and Cd^II were obtained by the reaction of 4,4′‐azopyridine (azpy) with metal tri‐tert‐butoxysilanethiolates (Co, 1 ; Cd, 2 ), acetylacetonates (Ni, 3 ; Zn, 4 ), and acetates (Cd, 5 ). All compounds were characterized by single‐crystal X‐ray structure analysis, elemental analysis, FTIR spectroscopy, and thermogravimetry. Complexes 1 , 2 and 4 , 5 exhibit diverse structural conformations: 1 is bimetallic, 2 and 4 are 1D coordination polymers, and 5 is a 2D coordination framework formed from bimetallic units. The obtained complexes contain metal atoms bridged by a molecule of azpy. The luminescent properties of 1–5 were investigated in the solid state.     

Complexes of N‐Thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)2 with Zinc(II), Cadmium(II), Nickel(II), and Cobalt(II) Cations

Reaction of the potassium salt of N‐thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)₂ ( HL ) with Zn^II, Cd^II, Ni^II and Co^II in aqueous EtOH leads to complexes of common formula M(L‐S,S′)₂ ( ML₂ ). Complexes were investigated by IR, UV‐Vis, ¹H and ³¹P{¹H} NMR spectroscopy and microanalysis The structure of complex NiL₂ was investigated by single crystal X‐ray diffraction analysis. The nickel(II) ion has a squre‐planar environment, S₄, with two anionic ligands involving 1,5‐S,S′‐coordination mode. The ligands are bound in a trans configuration.     

Zinc(II), Cadmium(II), and Mercury(II) Complexes of 2-Methyl-benzoselenazole

The following zinc(II), cadmium(II) and mercury(II) complexes of 2-methyl-benzoselenazole (L) have been prepared and studied by conductometric and i.r. methods: MLX₂ (M ? Cd, Hg, X ? Cl, Br, I), ML_1.5X₂ (M ? Zn, X ? ClO₄(4 H₂O); M ? Hg, X ? NO₃, ClO₄), ML₂X₂ (M ? Zn, X ? Cl, Br, I, NO₃; M ? Cd, X ? NO₃, ClO₄). The ligand is N-bonded. All the anions are coordinated.     

Kinetics of Acid‐Catalyzed Dissociation of Nickel (II) N‐Alkyl‐Substituted Diamino Diamide Complexes

The dissociation kinetics of the nickel (II) complexes of 4‐methyl‐4,7‐diazadecanediamide (4‐Me‐L‐2,2,2), 4,7‐dimethyl‐4,7‐diazadecanediamide (4,7‐N, N′‐Me2‐L‐2,2,2), 4‐ethyl‐4,7‐diazadecanediamide (4‐Et‐ L‐2,2,2), and 4‐methyl‐4,8‐diazaundecanediamide (4‐Me‐L‐2,3,2) have been studied at 25.0 °C and μ = 4.0 M (NaClO₄ + HClO₄) by the stopped‐flow method. These reactions are specific‐acid catalyzed; however, the rate constants of these reactions do not depend on the concentrations of acetic, chloro acetic, and dichloroacetic acids. At pH values be low 1.0, both the proton‐assisted and the direct protonation path ways make contributions to the rates. The ratios of the rate constant of dissociation by the direct protonation path way to the rate constant by the proton‐assisted path way for the complexes in aqueous solution were measured and discussed.     

Synthesis,Electronic and IR Spectral Studies of Some Polymeric Cobalt(II), Nickel(II), Zinc(II) and Cadmium(II) Azido Complexes with Hydrazine

A series of polymeric cobalt(II), nickel(II), zinc(II) and cadmium(II) azido complexes with hydrazine of the type [M(N₂H₄)(H₂O)(N₃)Cl]_n, [M(N₂H₄)(N₃)₂]_n and [M(N₂H₄)₂(N₃)₂]_n have been prepared. These were characterized by elemental analyses, magnetic susceptibility measurements, electronic and IR spectra. The complexes are highly insoluble in polar and non polar solvents. All the complexes decompose with explosion at different temperatures between 100°C to 200°C. The magnetic moment and electronic spectral data for Co(II) and Ni(II) complexes suggest that the complexes have octahedral structure. The ligand-field parameters (10 Dq, B, β, β° and LFSE) have also been calculated for all Co(II) and Ni(II) complexes which indicate a significant covalent character of M-L bonds. The IR spectra of the complexes show that the azide group and hydrazine molecule both act as bidentate bridging ligands in [M(N₂H₄)(H₂O)(N₃)Cl]_n and [M(N₂H₄)(N₃)₂]_n type complexes but the azide group is terminally bonded to metal in all [M(N₂H₄)₂(N₃)₂]_n type complexes.     

Syntheses of N,N′-Bis(salicylideneiminoethyl)oxamidatodicopper(II), N,N′-Bis(salicylideneiminoisopropyl)-oxamidatodicopper(II), and N,N′-Bis(2-pyridylideneiminopropyl)oxamidatodicopper(II) Nitrate and Corresponding Perchlorate

Reactions of coordinated functional groups were carried out as follows: The product formed by reaction of A-1a

1 The four new complexes are shown as A-3a, A-3b, B-3a, and B-3b (cf. Fig. 1), and other related complexes are shown as A-1a, A-1b, A-2a, A-2b, B-n, B-1, B-4, and B-5 (cf. Fig. 2)

or A-1b with copper(II), reacts with salicylaldehyde to give A-3a or A-3b, respectively. And the product formed by reaction of B-1 with copper(II), reacts with pyridine-2-aldehyde to give B-3a or B-3b. The four binuclear copper(II) complexes thus isolated as the new compounds have been characterized by elemental analyses, u.v. and i.r. spectra, magnetic susceptibility, and electronic conductivity measurements. Attempts to exchange the reactants with one another were unsuccessful.     

Acid Dissociation Behaviour and Complexation with Nickel(II), Copper(II) and Zinc(II) for Two Conformational Isomers of Dicyclohexylcyclam

Abstract

Acid dissociation constants for two conformational isomers of dicyclohexylcyclam, cis-anti-cis, (P) and cis-syn-cis, (N) have been determined at 25, 35 and 40°C, and thermodynamic data are estimated. It was found that (N) shows very different behaviour from (P). Stability constants of (P) and (N) toward Ni(II), Cu(II) and Zn(II) have been determined by pH-titration at 25°C by using a ligand exchange reaction. It is found that the (P) complex is more stable for Ni(II) and the (N) complex is more stable for Cu(II). Contributions of the cyclohexyl group to the macrocyclic effect (ME) have been also estimated by considering basicity corrections. It is found that substitution of the cyclohexyl group in cyclam increases ME only for the Ni(II) complex of (P).     

Zinc(II), Cadmium(II), Mercury(II), and Lead(II) Complexes of N-Carboxymethyl-D,L-threonine in Aqueous Solution

The formation of complexes of Zn(II), Cd(II), Hg(II), and Pb(II) and N-carboxymethyl-D,L-threonine (H₂CMT, H₂L) in aqueous solutions has been studied by spectrophotometric and potentiometric methods. The complexation model for each system has been established by the HYPERQUAD program from the potentiometric data. Three different behaviors are found: ML₂H, MLH, ML, MLOH, and ML₂ complexes are formed by Zn(II) and Cd(II) ions, ML₂H, ML, MLOH, and ML₂ are formed by Hg(II) ion, and only 1/1 complexes MLH, ML, and MLOH are formed by the Pb(II) ion. The formation constants determined for all these complexes allow simulation of experimental titration curves with good agreement. The speciation of multimetal systems with H₂CMT shows that this compound is a good and selective ligand at low pH for the Hg(II) ion.     

A Catalytic Method for Determining Cadmium(II), Nickel(II), and Zinc(II) Inhibitor Metals

The inhibitory effect of Cd(II), Ni(II), and Zn(II) on the oxidation of 3,3′,5,5′ -tetramethylbenzidine with periodate was detected. The optimum reaction conditions were found, and the procedures were developed for determining 1 × 10⁻² to 10 μg/mL Cd(II), Ni(II), and Zn(II) in solution. The indicator reaction was performed on a number of supports. The maximum inhibitory effect was observed on silica gel-based plates for TLC. Procedures for determining 6 × 10⁻³ to 0.4 μg of these metals were developed. Silica gel plates with the immobilized reagent for cadmium (bromobenzothiazo) were used to preconcentrate cadmium. A selective test procedure was developed for determining 1 × 10⁻⁴ −3 × 10⁻³ μg/mL cadmium with the visual detection of the process rate. Upon the introduction of dimethylglyoxime into the indicator reaction, the inhibitory effect of nickel changed to its promoting effect and the detection limit for nickel was lowered. A procedure was developed for determining 3 × 10⁻⁴ −3 × 10⁻³ μg/mL nickel in solution and 7 × 10⁻³−4 × 10⁻¹ μg nickel on the surface of Sorbfil plates. An assumption was made about the reasons for the inhibitory effect of metal ions on the oxidation of aryl diamines with periodate.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 662–669.Original Russian Text Copyright © 2005 by Beklemishev, Kiryushchenkov, Stoyan, Dolmanova.     

Synthesis and Properties of Complexes of Lead(II), Cadmium(II), and Zinc(II) with N-Phosphonomethylglycine

Summary.  Sparingly water soluble complexes of lead(II), cadmium(II), and zinc(II) with N-phosphonomethylglycine (glyphosate, NPMG) of the general formulae C₃H₆O₅NPPb, C₃H₆O₅NPCdċ2H₂O, and C₃H₆O₅NPZn were synthesized. The complexes were also precipited from a dilute Roundup solution, and their solubility in water was determined. Thermal, diffractometric, and IR spectrophotometric analyses were carried out. It was found that the metal is bonded to glyphosate through the oxygen atoms of the carboxylic and phosphonate groups; metal-nitrogen binding is absent in the above compounds. Studying the complexing behaviour in solution by UV spectrophotometry pointed out that a complex of the composition Pb(II) : NPMG=1:1 with an absorption band at 232 nm is formed. Its stability constant as determined by Job’s method is logK=5.9±0.1. Using potentiometric techniques, the dissociation constant of N-phosphonomethylglycine and the stability constants of its complexes with cadmium (II) and zinc (II) were determined. Received June 30, 1999/Accepted July 21, 1999.     

Zinc(II), Cobalt(II) and Nickel(II) Complexes of 5-Substituted-1,3,4-Thiadiazoles

Zn(II), Co(II) and Ni(II) complexes with some 5-substituted-1,3,4-thiadiazoles (L₁-L₄) have been prepared and characterized by conductivity, microanalysis, thermal analysis, infrared and electronic spectra measurements. All complexes behave as 1:1 electrolyte and the ligands are coordinated as bidentate molecules. The stability constants and energy of formation are determined and discussed on the basis of the ligands structure.     

The Preparation and Structural Study of Nickel (II) Complexes of N,N′-(8-Quinolyl)Trimethylenediamines

A number of Ni(II) complexes of N,N′-bis(8-quinolyl)trimethylenediamines are synthesized both as perchlorate salts and neutral amino complexes. Substitutions on the 2 and 6 positions of the quinolyl ligands are introduced for various reasons concerning the structural studies. The structural informations are obtained by studies of the magnetic properties, electronic spectra and NMR spectra. Structural changes effected by acid/base property of the medium are followed by NMR spectroscopy.     

Synthesis, Characterization and the Antioxidative Activity of Zinc(II), Copper(II) and Nickel(II) Schiff-base Complexes

A naringenin Schiff-base ligand (H₃L) and its three complexes, MHL . nH₂O (M = Zn and Cu, n = 0.5) and NiH₂LOAc . 3.5H₂O, have been synthesized and characterized on the basis of elemental analysis, molar conductivity and i.r. spectrum, ¹H-n.m.r., u.v. spectra and thermal analyses. In addition, the suppression ratio for O₂^−˙ (a) and the suppression ratio for OH˙(b) were determined by the use of spectrophotometric methods. IC₅₀(a) and IC₅₀(b) of the complexes are given. The results show that compared to the ligand, the complexes exhibit high activity in the suppression of O₂^−˙ (a) and OH˙(b).     

Nickel(II) and Zinc(II) Complexes with Benzoylacetaldehyde Derivatives

Russian Journal of Coordination Chemistry - Ni(II) and Zn(II) complexes, [M(Ln)A] (n = 1–3, A = NH3, Py), were prepared from the products of condensation of benzoylacetaldehyde with aromatic...     

Synthesis, Spectral and Thermal Studies of o-vanillin Oxime Complexes of Zinc(II), Cadmium(II) and Mercury(II)

Zinc(II), cadmium(II) and mercury(II) complexes of o-vanillin oxime have been synthesized and characterized by different physicochemical techniques. All the complexes have been subjected to non-isothermal decomposition studies in nitrogen atmosphere using thermogravimetry. The kinetic parameters for the decomposition of these complexes were evaluated using different methods and comparatively better results were obtained by these different methods. It has also been found that the decomposition processes of all these complexes follow first order kinetics. This revised version was published online in July 2006 with corrections to the Cover Date.     

One-and Two-photon Excited Fluorescence of Zinc(II),Cadmium(II)Complexes Containing Phenothiazine Ligand

In fluorescence imaging, two-photon excitation (TPE) has developed as an important alternative to traditional one-photon excitation (OPE) in fluorescence microscopy and spectroscopy1,2. The intrinsic advantages of the two-photon excitation include reduced background fluorescence from fluorophores outside the focal volume, decreased photobleaching, inherent optical sectioning capability, and lower photodamage of sensitive biological sample3. But, all the reported materials, which exhibit a …     

Synthesis and Characterization of Complexes of Copper(II), Nickel(II) and Cobalt(II) with vic-Dioximes Bearing N''-p-Aminobenzoyl Benzaldehyde Hydrazone

Six different arylhydrazone derivatives of p-aminobenzoic hydrazide of vic-dioximes were synthesized by reaction of chloroglyoxime and dichloroglyoxime with N＇-p-aminobenzoyl benzaldehyde, 4-hydroxybenzaldehyde and 4-methoxybenzaldehyde hydrazones, respectively. Metal-ligand （1 ： 2） complexes of vic-dioxime derivatives with Cu（Ⅱ）, Ni（Ⅱ） and Co（Ⅱ） were prepared from corresponding metal acetates. The ligands and their complexes were characterized on the basis of elemental analyses and spectral data. The complexing abilities of these new vic-dioximes toward transition metals of Co（Ⅱ）, Cu（Ⅱ）, Ni（Ⅱ）, Zn（Ⅱ）, Cd（Ⅱ）, Mn（Ⅱ） and Cr（Ⅲ） were determined by solid-liquid extraction studies.     

Synthesis, Characterization and the Antioxidative Activity of Copper(II), Zinc(II) and Nickel(II) Complexes with Naringenin

New complexes of Cu^(II), Zn^(II) and Ni^(II) with naringenin have been synthesized and characterized on the basis of elemental analyses, molar conductivities, ¹H-n.m.r., i.r. spectra, u.v. spectra, thermal analyses, and fluorescence spectra. In addition, the suppression ratio for O₂⁻· (a) and OH· (b) of the complexes were studied by spectrophotometric methods. The results show that the effect of the Cu^(II)-complex IC₅₀ (a) = 0.003 μm, IC₅₀ (b) = 0.06 μm is the most remarkable, and the average scavenger ability of the complexes (IC₅₀=0.06–2.67μm) against OH· is higher than that of the ligand (IC₅₀ = 28.5 μm). Taken together, these results indicate that the scavenger effect can be enhanced by the formation of metal-ligand coordination complexes, and the transition-metal ions may have differential and selective roles.