Magnetic properties of new copper(II) and [copper(II)]3-manganese(II) complexes of [14]N4 macrocyclic oxamides

Four new complexes of [14]N4 macrocyclic oxamides, namely [CuL1], [CuL2], [(CuL1)3Mn](ClO4)3 and [(CuL2)3 Mn](ClO4)3 [L1 and L2 are the dianions of 2,3-dioxo-5,6: 3,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene (H2L1) and 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclo-tetradeca-7,11-diene (H2L2), respectively], have been prepared and characterized. The observed magnetic susceptibilities of the [(CuL1)3Mn] (ClO4)3 complex over the ca. 2–300 K range have been fitted to theoretical equations based on the Heisenberg spin Hamiltonian =–2JMn(Cu1+ Cu2+Cu3) and molecular field approximation. The results indicated that both the intramolecular and intermolecular magnetic interactions are antiferromagnetic with JCuMn= –19.8cm–1 and zJ=–1.41cm–1.     

Kinetics and mechanism of the reaction of a quasi-aromatic copper(II) complex, [Cu(PnAO)-6H]0, with formaldehyde

The kinetics of the reaction of CH₂O with a quasi-aromatic metal complex (1,1,2,8,9,9-hexamethyl-4,6-dioxa-5-hydro-3,7,10,14-tetraazacyclotetradecane-2,7,10,12-tetraene)copper(II), [Cu(PnAO)-6H]⁰ (AH), have been studied spectrophotometrically under neutral conditions in 1/3(v/v) MeOH–H₂O. The Cu, 2N, 3C quasi-aromatic heterocyclic ring in AH is highly reactive towards CH₂O at the central-aromatic-carbon atom, C(12) and the following reaction mechanism is proposed. The compounds AH, A—CH₂OH and A—CH₂—A were isolated and identified by i.r spectroscopy and by elemental analysis. The kinetic data supported the proposed reaction sequence. All reactions were second order overall. The rate constants and corresponding activation parameters for every step were obtained and are discussed.     

Kinetics and mechanism of dissociation of ethylenedibiguanidenickel(II) and copper(II) and of bisbiguanide-nickel(II) in acid

Summary The kinetics of dissociation of the ethylenedibiguanidenickel(II) and copper(II), [M(EndibigH₂)]²⁺, where M = Ni^II or Cu^II, and bisbiguanide-nickel(II), [Ni(BigH)₂]²⁺, complexes in acid media forming the aquo-metal ions and the protonated ligand as the ultimate products have been studied by the stopped-flow technique. The reactions occur in two consecutive steps, the first being faster than the second, forming aquometal ions and protonated ligands as the ultimate products. For each step the rate is acid dependent and may be expressed by: k_x = k _x [H⁺] + k _x [H⁺]², where k_x is the observed rate constant and x = f or s for fast and slow steps respectively. Both paths (k _x and k _x ) contribute in the ethylenedibiguanidenickel(II) system, whereas k _x paths are virtually absent in the corresponding copper(II) complex; k _x paths are absent in the bisbiguanidenickel(II) system. A likely mechanism involves protonation of the bound ligand which facilitates its dissociation. A comparison of the S values indicates considerable solvent participation in the transition state, suggesting an assisted dissociative mechanism, which also accounts for the low H values. The observed lability order is [Ni(EndibigH₂)]²⁺ < [Ni(BigH)₂]²⁺ =ca. [Cu(EndibigH₂)]²⁺, and [Cu(BigH)₂]²⁺ dissociates under comparable conditions at a rate too fast to be measured by the stopped-flow method.     

Synthesis, characterization and structure of complexes of o-aminophenol-N,N,O-triacetic acid with cobalt(II), nickel(II), manganese(II) and zinc(II)

The potassium salt of o-aminophenol-N,N,O-triacetic acid (APTA) and KMnL·H₂O, KCoL·3H₂O, KNiL·3H₂O, KZnL·3ZH₂O, Co(CoL)₂·7H₂O and Ni(NiL)₂·8H₂O(L³⁻:anion of APTA) have been synthesized and characterized by elementary analysis, thermogravimetric analysis, molar conductance, IR spectra, magnetic measurements and electronic spectra. The coordination environments of these metal ions have been discussed on the basis of these studies. The single crystal structure of cobalt(II)-APTA has been determined as CoL·0.5Co(H₂O)₆·4H₂O, which contains two types of cobalt(II). One type of cobalt(II) is coordinated with six water molecules to form Co(H₂O)₆²⁺, the other is chelated by APTA to form a distorted octahedron and linked into an infinite chain anion [COC₆H₄(OCH₂COO)N(CH₂COO)₂⁻]_n, in which each cobalt(II) atom is linked with neighbouring cobalt(II) atoms through two carboxylate oxygen atoms of the phenoxyacetate group. Water molecules occupy interstices in the structure.     

Mixed pseudohalide complexes of copper(II). Crystal and molecular structure of [Cu(N3)(NCS)(tmen)] n and of [Cu(N3)(NCO)(tmen)]2 (tmen = N,N,N′,N′-tetramethylethylenediamine)

The compounds [Cu(N₃)(NSC)(tmen)]_n (1), [Cu(N₃)(NCO)(tmen)]_n (2) and [Cu(N₃)(NCO)(tmen)]₂ (3) (tmen=N,N,N′,N′-tetramethylethylenediamine) were synthesized and studied by i.r. spectroscopy. Single crystals of compounds (1) and (3) were obtained and characterized by X-ray diffraction. The structure of compound (1) consists of neutral chains of copper(II) ions bridged by a single azido ligand showing the asymmetric end-to-end coordination fashion. Each copper ion is also surrounded by the other three nitrogen atoms; two from one N,N,N′,N′-tetramethylethylenediamine and one from a terminal bonded thiocyanate group. Compound (2) decomposes slowly in acetone and the product formed [Cu(N₃)(NCO)(tmen)]₂ (3) crystallizes in the monoclinic system (P2₁). The structure of (3) consists of dimeric units in which the Cu atoms are penta-coordinated and connected by μ(1,3) bridging azido and cyanate ligands. In both cases the five coordinated atoms give rise to a slightly distorted square-based pyramid coordination geometry at each copper ion. The thermal behavior of [Cu(N₃)(NSC)(tmen)]_n (1) and [Cu(N₃)(NCO)(tmen)]_n (2) were investigated and the final decomposition products were identified by X-ray powder diagrams.     

Extraction and complexing of copper(II) with benzoic acid N,N-dihexylhydrazide

The solubility and acid-base properties of benzoic acid N,N-dihexylhydrazide (BDHH) were studied. The extraction of copper(II), cobalt(II), nickel(II), zinc(II), iron(III), platinum(II), platinum(IV), chromium(III), chromium(VI), palladium(II), and molybdenum(VI) with this reagent was studied. It was shown that BDHH most efficiently extracts copper(II) from ammonia solutions and chromium(VI) from sulfuric acid solutions. In the extraction of copper(II), complexes with the [Cu(II)]: [BDHH] = 1: 1 and 1: 2 stoichiometries were found to form. The structure of the 1: 2 complex was suggested proceeding from its IR spectra. A copper(II) extraction isotherm was plotted.     

Cu(II)氧化抗坏血酸的动力学和机理

本文在总离子强度I=1.00mol.dm^-^3、[Cu^2^+]>>[H2A]、[H^+]>>[H2A]、无氧及无缓冲剂存在的条件下, 研究Cu(II)氧化抗坏血酸(H2A)的动力学和机理. 发现Cu(II)与H2A不发生配位反应, 但以Cl^-存在的情况下, 确有Cu(II)的H2A配合物生成, Cu(II)氧化H2A反应的速率方程为r={a+b[Cl^-]}[Cu^2^+]{[H+]+Ka}^-^2, 25℃时a和b值分别为4.08×10^-^4s^-^1和0.555dm^3.s^-^1.mol^-^1. Cu(II)氧化H2A反应的表观活化能为68.1KJ.mol^-^1. 根据动力学结果, 提出了反应机理, 并给出了配合物ClCuHA的结构形式.     

Kinetics of metal exchange reaction of Cu(II)-poly(vinyl alcohol) complex with Ca(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid in aqueous solution

The kinetics of the metal exchange reaction between the Cu(II)-poly(vinyl alcohol) complex (Cu(II)-PVA) and Ca(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid (Ca(II)-EDTA) were studied by mixing both solutions in a spectrophotometer at pH 9.7–11.0, at μ = 0.10(KNO₃) and at 25°C. The reaction is initiated by the formation of unstable Cu(II)-H-PVA by the attack of H⁺ to Cu(II)-PVA, and while both ligand exchange and metal exchange steps occur, the latter may be rate-determining. The kinetic expression of this reaction was determined as -d[Cu(II)-PVA]/dt = k[Cu(II)-PVA] [H⁺] [PVA]/[Ca(II)-EDTA], where k = k₁ + k′₂[H⁺], k₁ = 3.85 × 10⁻² sec⁻¹, k₂ = k′₂ · K^−H_Cu(II)-H-PVA 9.59 × 10⁵ 1 mol⁻¹ sec⁻¹.     

Kinetics and mechanism of the reaction betweencis-dichlorobisbipyridineruthenium(II) and nitric acid in water-methanol solutions

Summary The kinetics of the reaction betweencis-dichlorobisbipyridineruthenium(II) and nitric acid have been investigated spectrophotometrically in the 25°–40° range in the presence of 0.03 to 0.2 mol dm^–3 HNO₃. The reaction proceeds with the stepwise formation of monoaqua and diaqua products. Only the formation of the monoaqua intermediate was followed as this species could not be obtained in a pure state. Aquation proceeds through a dissociative process. The second order rate constants are 11.8 (25°), 17.5 (30°); 30.0 (35°) l mol^–1 s^–1. Activation parameters are H 52±3 kJ mol^–1; S–108±8 JK^–1 mol^–1.     

Complex equilibria of molybdenum(V) and molybdenum(VI) witho-hydroxybenzylamine-N,N,O-triacetic acid (HBATA)

Summary Complex reactions between Mo^V.VI ando-hydroxybenzylamine-N,N,O-triacetic acid (HBATA) have been investigated in the 1–3 and 2.8–6.5 pH range by potentiometric titration at 30° C in 0.5 mol dm^–3 NaCl. The equilibrium data were analyzed with the SCOGS2 and MINIQUAD programs, taking into account side reactions of Mo^V.VI and HBATA with hydrogen ion. The favorable reaction model comprises two complexes, (1,1,1)⁺ and (1,2,2)^–, with formation constants log ₁₁₁ = 14.85 ± 0.11 and log ₁₂₂ = 28.51 ± 0.08 for the Mo^V-HBATA system and the two complexes (1,1,2)^3– and (1,1,3)^2– with formation constants log ₁₁₂ = 17.36 ± 0.01 and log ₁₁₃ = 20.60 ± 0.01 for the Mo^VI-HBATA system. The numbers in brackets refer to the chemical stoichiometric coefficients of molybdenum, HBATA and hydrogen ion in the complexes. The structure and coordinating behaviours of Mo^V and Mo^VI complexes are discussed. The equilibria studied for the polymerization of Mo^V indicates that dimeric, trimeric and tetrameric species are present at pH 1–3.     

二(桥-氯)-二[氯-(N,N,N''''-三苄基乙二胺)铜(Ⅱ)]的晶体结构

0 IntroductionThe copperdim er,bis(μ鄄hydroxo)鄄bis[chloro(N,N,N',N'鄄tetram ethylethylenediam ine) copper髤] chloride(Cu(OH )Cl·TM EDA),prepared from N,N,N',N'鄄tetram鄄ethylethylenediam ine (TM EDA) and CuCl, exhibitedexcellentcatalytic activity for t     

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.     

Kinetics and mechanism of chelating reaction between chitosan derivatives with Ca(II)

Chitosan derivatives, such as chitosan alpha-ketoglutaric acid (KCTS) and hydroxamated chitosan alpha-ketoglutaric acid (HKCTS), are prepared and their coordination behavior toward Ca(II) was studied. The adsorption isotherms were correlated by dc/dt?=??kcⁿ at 20°C, 30°C, 40°C, 50°C, and 60°C. By linear correlation, the shapes of the isotherm curves were similar to the kinetic function of 1/c?=?kt and the rate equation was dc/dt?=??kc ²; the activation energies were 13.31 and 14.76?kJ?mol^?1 for KCTS and HKCTS, respectively. The overall rate of Ca(II) adsorption is likely to be controlled by the chemical process. The coordination mechanism of chitosan derivatives with Ca(II) was studied by infrared and X-ray photoelectron spectroscopy. The results indicated that –NH– of KCTS was coordinated. Nitrogen of amino, oxygens of hydroxamic acid, and carbonyl in HKCTS coordinated with Ca(II).