Complexes of hydroxamates X. Interaction of methioninehydroxamic acid with Ni(II) and Pd(II). Kinetics and reaction mechanism

The kinetic stopped flow method has been used to study the reaction rates of Ni(II) and Pd(II) with methioninehydroxamate (MX). Two reaction rates were observed in the MX? Ni(II) system whereas three rates were observed in the MX? Pd(II) system. Most of the rate steps were dependent on pH as well as on T_MX (total concentration of methioninehydroxamate). The observed pseudo-first-order rate constants at constant pH are expressed empirically as k = m_i + m′_i T_MX. The parameters m_i and m′_i are pH-dependent. It has been concluded that hydroxy metal species contributed to the explanation of the rate of the metal complexation with MX. Similar systems have been correlated with the systems of current work. © 1995 John Wiley & Sons, Inc.     

Potentiometrische Untersuchungen an Cu(II)- und Ni(II)-Komplexen mit gemischten Liganden

Potentiometric evidences have been cited for the formation of 1∶1∶1 ternary complexes in the systems: Cu(II)/Ni(II)-glycine-diamines [where diamines = ethylenediamine (en), propylenediamine (pn), o-phenylenediamine (phenen) and 1.8-naphthalenediamine (naphen)].     

Stability of Copper(II), Nickel(II) and Zinc(II) Binary and Ternary Complexes of Histidine,Histamine and Glycine in Aqueous Solution

The binary and mixed-ligand complexes formed between ligands (histidine (His), histamine (Him) and glycine (Gly)) and some transition metals (Cu(II), Ni(II) and Zn(II)) were studied potentiometrically in aqueous solution at (25.0 ± 0.1) C and I = 0.10 M KCl in order to determine the protonation constants of the free ligands and stability constants of binary and ternary complexes. The complexation model for each system has been established by the software program BEST from the potentiometric data. The most probable binding mode for each binary species of histidine and for all mixed species was also discussed based upon derived equilibrium constants and stability constants related to the binary species. The ambidentate nature of the histidine ligand, i.e. the ability to coordinate histamine-like, imidazolepropionic acid-like and glycine-like modes was indicated from the results obtained. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameters, log K, log X and ₁₁₁₀. The concentration distributions of various species formed in solution were also evaluated. In terms of the nature of metal ion, the complex stability follows the trend Cu(II) > Ni(II) > Zn(II), which is in agreement with the Irving-Williams order of metal ions. Thus, the results obtained were compared and evaluated with those in the literature.     

镍, 锌, 钴(II)-N-(间甲苯基)亚氨基二乙酸-氮三乙酸的量热研究

使用改进的RD-1型热导式量热计测量了镍(II), 锌(II),钴(II)-N-(间甲苯基)亚氨基二乙酸-氮三乙酸三元配合物的生成焓, 发现其大小按金属离子来说符合Irving-William序列。利用配体的多环水化结构等讨论了该三元配合物的生成焓和相应的二元配合物的生成焓, 同时求得了上述三元体系的热力学参数, 指出上述三元体系的生成熵是导致这些三元体系具有较大稳定性的根本原因。     

Electrometric Studies on the Ternary Complexes of M(II) With Chlorpromazine and Some Amino Acids

 The stability constants for the binary M(II)- chlorpromazine hydrochloride (CPZ) and the ternary complexes M(II)-chlorpromazine-amino acid, have been studied using pH-measurements. The amino acids (aa) are: glycine, glutamic acid, histidine and the metal ions are: Cu(II), Zn(II), Co(II), Ni(II) and UO₂(II). All experiments were carried out in the presence of 0.1 mol dm⁻³ KNO₃. The resulting stability constants of the binary and the ternary complexes were compared. It was observed that the stability of the ternary complexes-except for glutamic acid – are lower than of the binary ones. Received October 22, 1998. Revision March 14, 1999.     

Studies of Mn(II), Co(II), Ni(II) and Cu(II) Chelates with 3-phenyl-4-(p-methoxy- phenylazo)-5-pyrazolone

Mn(II), Co(II), Ni(II) and Cu(II) chelates with3-phenyl-4-(p-methoxyphenylazo)-5-pyrazolone have been synthesized and were characterized by elemental and thermal analyses as well as by IR, UV-VIS, ¹HNMR, conductometric and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows the presence of water of hydration, the second denotes the removal of the coordinated water molecules. The final decomposition products were found to be the respective metal oxides. The data of the investigated complexes suggest octahedral geometry with respect to Co(II) 1:1, tetrahedral for Ni(II) 1:1and 2:3; square planar for Cu(II) 1:1 and 2:3; the complexes with no coordinated water molecules (2:3) Co(II) and Mn(II) complexes are tetrahedral. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spectral,thermal and magnetic investigations of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates were investigated and their composition, solubility in water at 295 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with molar ratio of metal to organic ligand of 1.0:1.0 and general formula: M [ CH₃C₆H₃(CO₂)₂]·nH₂o (n=1-3) were recorded and their decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Mn, Co, Ni, Zn, Cd) or two steps (Cu) and next the anhydrous complexes decompose to oxides directly (Cu, Zn), with intermediate formation of carbonates (Mn, Cd), oxocarbonates (Ni) or carbonate and free metal (Co). The carboxylate groups in the complexes studied are mono- and bidentate (Co, Ni), bidentate chelating and bridging (Zn) or bidentate chelating (Mn, Cu, Cd). The magnetic moments for paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.92, 5.05, 3.36 and 1.96 M.B., respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Self-assembly of supramolecular Ni(II) and Cu(II) metalmacrocyclic compounds with tetraazamacrocyclic ligand into a gelatin-immobilized matrix

Self-assembly in M(II)-ethanedithioamide [H₂N–C(=S)–C(=S)–NH₂]-propanone triple systems (M=Ni, Cu) into corresponding metal(II) hexacyanoferrate(II) gelatin-immobilized matrix systems under contact with aqueous-alkaline (pH?～?12) solutions containing ethanedithioamide and propanone have been studied. Formation of supramolecular macrotetracyclic compounds of Ni(II) and Cu(II) with 2,7,7,9,14,14-hexamethyl-3,6,10,13-tetraazacyclotetradecadien-2,9-tetrathione-4,5,11,12 containing original “kernel” (metal complex) and “shell” surrounding this “kernel”, of polypeptide chains of the gelatin molecules, occurs under such specific conditions.     

Copper(II), Nickel(II) and Cobalt(II) Complexes of Dibasic Tridentate Schiff Bases

Complexes of Cu(II), Ni(II) and Co(II) with the Schiff bases derived from o-aminobenzoic acid with salicylaldehyde and its 5-chloro and 5-bromo derivatives have been prepared. The 1:1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility and electronic spectra of Cu(II) complexes indicate the nonplanar binuclear structures while that of Ni(II) and Co(II) show their paramagnetic octahedral geometry. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type (Cu·L)₂, Ni·L·3H₂O and Co·L·3H₂O are formed having solvent molecule in coordination with the metal ion. The monopyridine and monoammonia adducts of Cu(II) complexes were found to be monomeric.     

Equilibrium and spectroscopic studies of ternary cadmium(II) and mercury(II) complexes with CMP and triamines

Formation of ternary Cd(II) and Hg(II) complexes with cytidine 5′-monophosphate (CMP) and triamines has been studied. Complexes M(CMP)(H _x PA) and M(CMP)(PA) (M?=?Cd, Hg; PA?=?polyamine) were detected and overall stability constants and equilibrium constants for their formation determined. The mode of coordination in the complexes has been proposed on the basis of the equilibrium and ¹³C, ³¹P NMR and IR studies. In the Hg(II) systems, metalation involves the donor endocyclic N(3) atom, the CMP phosphate group and nitrogen donor atoms of PA. Relative to the Hg/CMP binary systems, the presence of a polyamine in ternary systems does not change the metal–nucleotide mode of coordination. In ternary systems including Hg(II) ions, the occurrence of noncovalent interactions has not been detected. Cd(II) ions form molecular complexes as well as protonated species. Introduction of a polyamine to the Cd/CMP system changes the coordination mode of the nucleotide. The phosphate group of CMP is inactive in binary complexes (metalation by the N(3) atom) but is involved in coordination in heteroligand species. In contrast to other polyamines studied, in the system including 1,7-diamino-4-azaheptane (3,3-tri), the phosphate group of CMP in Cd(CMP)(H3,3-tri) does not participate in metalation but is engaged in intramolecular noncovalent interactions that stabilize the complex.     

Spectrophotometric Studies of Nickel(II) and Copper(II) Chelates of p-(2-Hydroxy-1-Naphthylazo)-Benzenesulphonate

The ionization constant of p-(2-hydroxy-1-naphthylazo)benzene-sulphonate (Orange II) and the formation constants of the metal chelates of this reagent with Ni(II) and Cu(II) have been determined spectrophotometrically in aqueous solution at 25° and at an ionic strength of 0.10M. The ionization constant of orange II was found to be pK_a=10.95. Formation of orange II chelates with Ni(II) and Cu(II) was pH dependent, and the optimum pH range of the Ni(II) Chelate was at pH 9.2-9.4, and Cu(II) chelate at 9.5-9.7, respectively. The mole ratio of orange II to both of metal ions was found to be 2 to 1 stoichiometry. The formation constants (logK) of the Ni(II) and Cu(II) chelates were 12.50 and 16.11, respectively. The molar extinction coefficients and the photometric sensitivities of these chelates were determined.     

Spectral,thermal, electrochemical,biological and DFT studies on nanocrystalline Co(II), Ni(II), Cu(II) and Zn(II) complexes with a tridentate ONO donor Schiff base ligand

Co(II), Ni(II), Cu(II) and Zn(II) Schiff base complexes derived from 3-hydrazinoquionoxaline-2-one and 1,2-diphenylethane-1,2-dione were synthesized. The compounds were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV–vis, ¹H NMR, ¹³C NMR, ESR, and mass spectral studies. Thermal studies of the ligand and its metal complexes were also carried out to determine their thermal stability. Octahedral geometry has been assigned for Co(II), Ni(II), and Zn(II) complexes, while Cu(II) complex has distorted octahedral geometry. Powder XRD study was carried out to determine the grain size of ligand and its metal complexes. The electrochemical behavior of the synthesized compounds was investigated by cyclic voltammetry. For all complexes, a 2 : 1 ligand-to-metal ratio is observed. The ligand and its metal complexes were screened for their activity against bacterial species such as E. coli, P. aeruginosa, and S. aureus and fungal species such as A. niger, C. albicans, and A. flavus by disk diffusion method. The DNA-binding of the ligand and its metal complexes were investigated by electronic absorption titration and viscosity measurement studies. Agarose gel electrophoresis was employed to determine the DNA-cleavage activity of the synthesized compounds. Density functional theory was used to optimize the structure of the ligand and its Zn(II) complex.     

Potentiometric and spectrometric study: Copper(II), nickel(II) and zinc(II) complexes with potentially tridentate and monodentate ligands

Equilibrium and solution structural study of mixed-metal-mixed-ligand complexes of Cu(II), Ni(II) and Zn(II) with L-cysteine, L-threonine and imidazole are conducted in aqueous solution by potentiometry and spectrophotometry. Stability constants of the binary, ternary and quaternary complexes are determined at 25 ±1°C and in I= 0.1 M NaClO₄. The results of these two methods are made selfconsistent, then rationalized assuming an equilibrium model including the species H₃A, H₂A, A, BH, B, M(OH), M(OH)₂, M(A), MA(OH), M(B), M(A)(B), M₂(A)₂(B), M₂(A)₂(B-H), M¹M²(A)₂(B) and M¹M²(A)₂(B-H) (where the charges of the species have been ignored for the sake of simplicity) (A = L-cysteine, L-threonine, salicylglycine, salicylvaline and BH = imidazole). Evidence of the deprotonation of BH ligand is available at alkalinepH. N₁H deprotonation of the bidentate coordinated imidazole ligand in the binuclear species atpH > 70 is evident from spectral measurements. Stability constants of binary M(A), M(B) and ternary M(A)(B) complexes follow the Irving-Williams order.     

Solid phase extraction and diffusive gradients in thin films techniques for determination of total and labile concentrations of Cd(II), Cu(II), Ni(II) and Pb(II) in Black Sea water

Total dissolved and labile concentrations of Cd(II), Cu(II), Ni(II) and Pb(II) were determined at six locations of the Bourgas Gulf of the Bulgarian Black Sea coast. Solid phase extraction procedure based on monodisperse, submicrometer silica spheres modified with 3-aminopropyltrimethoxysilane followed by the electrothermal atomic absorption spectrometry (ETAAS) was developed and applied to quantify the total dissolved metal concentrations in sea water. Quantitative sorption of Cd, Cu, Ni and Pb was achieved in the pH range 7.5–8, for 30?min, adsorbed elements were easily eluted with 2?mL 2?mol?L^?1 HNO₃. Since the optimal pH for quantitative sorption coincides with typical pH of Black Sea water (7.9–8.2), on-site pre-concentration of the analytes without any additional treatment was possible. Detection limits achieved for total dissolved metal quantification were: Cd 0.002?µg?L^?1, Cu 0.005?µg?L^?1, Ni 0.03?µg?L^?1, Pb 0.02?µg?L^?1 and relative standard deviations varied from 5–13% for all studied elements (for typical Cd, Cu, Ni and Pb concentrations in Black Sea water). Open pore diffusive gradients in thin films (DGT) technique was employed for in-situ sampling and pre-concentration of the sea water and in combination with ETAAS was used to determine the proportion of dynamic (mobile and kinetically labile) species of Cd(II), Cu(II), Ni(II) and Pb(II) in the sea water. Obtained results showed strong complexation for Cu and Pb with sea water dissolved organic matter. The ratios between DGT-labile and total dissolved concentrations found for Cu(II) and Pb(II) were in the range 0.2–0.4. For Cd and Ni, these ratios varied from 0.6 to 0.8, suggesting higher degree of free and kinetically labile species of these metals in sea water.     

Characterization of Ni(II) and Cu(II) complexes of 4-(2-Quinolylmethyleneamino)-1-phenyl-2,3-dimethyl-5-pyrazolone and their analytical applications

A synthesis of the new reagent 4-(2-quinolylmethyleneamino)-1-phenyl-2,3-dimethyl-5-pyrazolone (QPP) and of its complexes with Ni(II) and Cu(II) is described. The structure of the ligand itself and the nature of the bonding in complex molecules were determined by elemental analysis, IR, and mass spectrometry. The analysis of data showed that isolated crystal metal complexes are of the ML₂ type. The composition and stability constants of the complexes in water/methanol solutions, (methanol) = 0.16, at constant temperature 25 ±1 °C and ionic strength of 0.5 M (KNO₃) at different pH (4, 6, 8, and 10) have been determined spectrophotometrically. The results indicate that the metal complexes formed in the solution have a metal-to-ligand ratio 1:2. The reaction of QPP with Ni(II) and Cu(II) in solution was quantitatively studied. The lowest detection limit for the determination of Ni is 0.3 μg/ml while that for Cu is 0.05 μg/ml under the investigated experimental Conditions.     

Complexes of Cobalt(II), Nickel(II) and Copper(II) Chloroacetates with Quinoline N-Oxide

Some 1:1 and 1:2 adducts of cobalt(II), nickel(II) and copper(II) chloroacetates with quinoline N -oxide have been isolated by the interaction of the appropriate metal chloroacetate with quinoline N -oxide (QuinNo). The complexes isolated are of 1:1 stoichiometry of formula [M(CH₃_xClxCOO)₂QuinNO] (when M=Co(II), Ni(II); X=1,2 and 3 and when M=Cu(II), X=l and 2) except copper(II) trichloroacetate which yields an adduct of 1:2 stoichiometry of formula[Cu(CCI₃COO)₂(QuinNO)₂]. The adducts isolated are soluble in common organic solvents.     

Binary,ternary and quaternary complexes invloved in the systems pyridoxamine-glycine-imidazole with some bivalent metal ions

Equilibrium-based computer models using MINIQUAD-75 program were utilized to determine the stoichiometry and formation constants involved in the systems pyridoxamine(Pm)-glycine (Gly)-imidazole (lmd) with CO(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions. The data were obtained from potentiometric pH titration of the various binary and ternary quaternary systems under physiological-like conditions (0.15 M NaNO₃-37°C). Various composition ratios of metal and ligands were used. The ligand concentrations did not exceed 4 times the concentration of metal ion in the binary systems and 4 times of the metal ions in ternary systems. In case of the quaternary systems only imidazole concentrations were two or four times the concentrations of metal ions keeping those of other ligands equal to that of metal ions. The stability constants of the quaternary species are discussed in terms of binary and ternary constants as are the effect of ring size on the stability of mixed ligand species. In addition, electrostatic as well as statistical effects also are mentioned and the biological implications of these model equilibria are described.     

Synthesis and characterization of a new Schiff base derived from 2,3-diaminopyridine and 5-methoxysalicylaldehyde and its Ni(II), Cu(II) and Zn(II) complexes. Electrochemical and electrocatalytical studies

We describe the synthesis and characterization of a new tetradentate Schiff base ligand obtained from 2,3-diaminopyridine and 5-methoxysalicylaldehyde. This ligand (H₂L) reacted with nickel(II), copper(II), and zinc(II) acetates to give complexes. The ligand and its metal complexes were characterized using analytical, spectral data (UV–vis, IR, and mass spectroscopy), and cyclic voltammetry (CV). The crystal structure of the copper complex was elucidated by X-ray diffraction studies. The electrochemical behavior of these compounds, using CV, revealed that metal centers were distinguished by their intrinsic redox systems, e.g. Ni(II)/Ni(I), Cu(II)/Cu(I), and Zn(II)/Zn(I). Moreover, the electrocatalytic reactions of Ni(II) and Cu(II) complexes catalyze the oxidation of methanol and benzylic alcohol.     

Complexes of Cobalt(II), Nickel(II) and Copper(II) Chloroacetates with Quinoline N-Oxide

Some 1:1 and 1:2 adducts of cobalt(II), nickel(II) and copper(II) chloroacetates with quinoline N -oxide have been isolated by the interaction of the appropriate metal chloroacetate with quinoline N -oxide (QuinNo). The complexes isolated are of 1:1 stoichiometry of formula (M(CH_3-xCl_xCOO)₂QuinNO) (when M=Co(II), Ni(Il); X=l, 2 and 3 and when M=Cu(II), X=1 and 2) except copper(II) trichloroacetate which yields an adduct of 1:2 stoichiometry of formula[Cu(CCl₃COO)₂ (QuinNO)₃]. The adducts isolated are soluble in common organic solvents.     

Spectrothermal studies on Co(II), Ni(II), Cu(II) and Zn(II) salicylato (1,10-phenanthroline) complexes

The cobalt, nickel, copper and zinc atoms in bis(1,10-phenanthroline)bis(salicylato-O)metal(II) monomeric octahedral complexes [M(Hsal)₂(phen)₂]·nH₂O, (M: Co(II), n=1; Cu(II), n=1.5 and Ni(II), Zn(II), n=2) are coordinated by the salicylato monoanion (Hsal) through the carboxyl oxygen in a monodentate fashion and by the 1,10-phenanthroline (phen) molecule through the two amine nitrogen atoms in a bidentate chelating manner. On the basis of the DTG_max, the thermal stability of the hydrated complexes follows order: Ni(II) (149°C)>Co(II) (134°C)>Zn(II) (132°C)>Cu(II) (68°C) in static air atmosphere. In the second stage, the pyrolysis of the anhydrous complexes takes place. The third stage of decomposition is associated with a strong exothermic oxidation process (DTA curves: 410, 453, 500 and 450°C for the Co(II), Ni(II), Cu(II) and Zn(II) complexes, respectively). The final decomposition products, namely CoO, NiO, CuO and ZnO, were identified by IR spectroscopy. This revised version was published online in July 2006 with corrections to the Cover Date.