Spectrochemical Properties of Noncubical Transition Metal Complexes in Solution. XII. Angular Overlap Studies of Salicylideneethylenediamine Cu(II) Complex in Various Solvents

As a part of our general interest in the UV-Vis spectroscopy of multidentate mixed-donor ligands, the (salicylideneethylenediamine)Cu(II) complex has been prepared and characterized by elemental analyses, solubility in common solvents, molar conductivities, and ultraviolet (UV), and visible (Vis) spectroscopy. The combined results of spectrophotometric measurements and EPR spectra, as well as known the X-ray structure for solids, were used to determine the structure of the investigated complex in solutions. The spectra of [Cu(salen)] (H₂salen = salicylideneethylenediamine), were measured in various solvents at room temperature, resolved by Gaussian analysis, and angular overlap model (AOM) treated in C _2v symmetry. Because of overparametrization problems, the bis(salicylaldehyde)Cu(II) complex has been characterized and AOM treated. The results of this have been used for AOM studies of [Cu(salen)]. The effect of the solvents upon the - and -bonding ligand abilities is discussed.     

Spectrochemical Properties of Noncubical Transition Metal Complexes in Solutions. XV. Solution Properties of bis(Salicylideneaniline)Copper(II)

The complex obtained by condensation of salicylideneaniline with copper(II) acetate was studied in a variety of solvents. This deep-brown crystalline compound is soluble in common solvents, such as, chloroform, toluene, dioxane, methanol, ethanol, dimethyl formamide, dimethyl sulfoxide, and acetonitrile—a necessary condition for observing solvatochromism. The complex has been characterized by elemental analysis, molar conductivity, EPR, and ultraviolet (UV) and visible (VIS) spectroscopy. The available X-ray data shows planar coordination geometry for the copper center. Combined multi-technique experiments have been applied to confirm the structure of the complex in solution. The molar conductivities indicate nonelectrolytic properties. EPR measurements preclude the possibility of solvent coordination at the axial positions of the complex. Spectroscopic measurements were used to study the coordination properties of donor atoms and their bonding ability, as well as trichromaticity coordinate calculations. The results obtained show that the interactions of metal with donors depend on donor strength and polarity of solvent.     

Spectrochemical Properties of Noncubical Transition Metal Complexes in Solutions. VIII. Angular Overlap Treatment of a Schiff Base Copper(II) Complex in Various Solvents

The electronic absorption spectra of trans-[Cu(Brsap)₂], where [HBrsap = 5-bromosalicylidine-o-aminopyridine (Schiff base)], were measured in various solvents at room temperature. The d-d transition energies were used to derive the angular overlap model (AOM) parameters in the C _2h symmetry. The experimental curves were resolved by Gaussian analysis. A comparison of the spectra and ligand field parameters in various solutions was made. The effect of the solvents upon the -, -bonding, and bite angle of the bidentate asymmetric ligand is discussed.     

Angular Overlap Studies of Mono-(Aminodiphosphonato)Copper(II) Complexes in Aqueous Solutions

Electronic absorption spectra of copper(II) complexes with iminodimethylenephosphonates R-N(CH₂PO₃H₂)₂ type (L, R-dmp), in aqueous solution have been characterized and quantitatively interpreted. The geometry of species in aqueous solution at pH 7–8 has been assumed on the basis of our previous combination of UV spectrophotometric measurements and ESR spectra, as well as data obtained from potentiometric titration. The ligand-field spectra (d–d transitions) of the [CuL(H₂O)_x]^2– chromophores (where x = 2, 3) have been treated by the angular overlap model (AOM) and C _2v symmetry. Low-symmetry splittings of the broad asymmetric bands in the spectra of solutions at room temperature were resolved by Gaussian analysis. The effect of the and bonding of the tridentate (and tetradentate) ligands (with oxygen-donor and nitrogen-donor ligators) on the central metal ion has been described in the ligand-field framework.     

Spectrochemical Properties of Noncubical Transition Metal Complexes in Solutions. IX. The Mixed Tetragonal Distorted Bis(Salicylato)Cobalt(II) Complex in Various Solvents

Mixed cobalt(II) complexes with the monodentate ligands: 2-hydroxybenzoic acid deprotonated (sal^–, the salicylate ion) and water, have been investigated. The combined results of the spectrophotometric and conductance measurements, as well as known the X-ray structure for solids, were used to determine the structure of the studied complexes in solution. The electronic absorption spectra in aqueous acid (0.01M HClO₄), ethylene glycol (glycol), formamide (FM), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) solutions have been recorded. The d-d electronic spectra have been treated by the crystal-field model (CFM) and angular overlap model (AOM). Low-symmetry splittings of the broad asymmetric bands in the experimental spectra (solutions at room temperature) were found by Gaussian analysis. The effect of the and bonding of the monodentate ligands (with oxygen-donor ligators) on the central metal ion was described in the ligand–field framework. A comparison of the stereochemistry of the complex species in various solutions was made.     

Spectrochemical Properties of Cobalt(II) Complex with Bidentate Schiff Base in Various Solvents

As a continuation of our previous studies on copper(II) complexes with a bidentate Schiff base derived from 5-bromosalicylaldehyde and -aminopyridine, we have investigated the electronic spectra of the cobalt(II) complex with this ligand. The complex is a red crystalline compound soluble in common solvents, such as chloroform, dioxane, dimethyl formamide, dimethyl sulfoxide, and methanol. The time-elapsed spectral measurements of the complex and ligand, as well as conductivities of the complex in chloroform and dioxane solutions, are presented and discussed. Molar conductivities indicate that the complex exists as a nonelectrolyte in nonpolar solvents and as a 1:1 or 1:2 electrolyte in polar solvents. The ligand-field parameters (CFM/AOM) for the complex in chloroform solution are estimated and discussed.     

Copper(II) complexes of schiff bases derived of 2-hydroxy-3-naphthaldehyde. The crystal and molecular structures of bis-{(phenyl)[(2-oxo-3H-naphth-3-ylidene)methyl]aminato}copper(II) and bis-{(benzene-4-trifluoromethyl)[(2-oxo-3H-naphth-3-ylidene)-methyl]aminato}copper(II)

Summary The Schiff base ligands, 3-[(Phenyl)-2-hydroxy-3H-Naphth-3-ylidene)methyl]aldamine (1) and 3-[(benzene-4-trifluoromethyl)-2-hydroxy-3H-naphth-3-ylidene)methyl]aldamine (2), and their corresponding Cu(II) complexes (I andII were synthesized. The crystal and molecular structures ofI andII were determined. CompoundI crystallizes in the triclinic crystal systema=10.804(5),b=12.589(5), andc=10.369(3) (Å), =107.72(3), =95.75(3), and =76.32(4)(°), in the space group P withZ=2. CompoundII crystallizes in the triclinic crystal systema=10.718(2),b=13.861(4), andc=10.110(9) (Å), =95.99(2), =90.16(2), and =93.90(2)(°), in the space group P withZ=2. The geometry around the metal atom in both complexesI andII is square planar.

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Kupfer(II)-Komplexe von Schiffbasen von 2-Hydroxy-3-naphthaldehyd. Die Kristall-und Molekülstrukturen von Bis{(phenyl)[(2-oxo-3H-naphth-3-yliden)methyl]aminato}kupfer(II) und Bis{(benzen-4-trifluoromethyl)[(2-oxo-3H-naphth-3-yliden)methyl]aminato}kupfer(II)

Zusammenfassung Es wurden die Schiffbasen-Liganden 3-[(Phenyl)-2-hydroxy-3H-naphth-3-yliden)-methyl]aldamin (1) und 3-[(Benzen-4-trifluoromethyl)-2-hydroxy-3H-naphth-3-yliden)-methyl]aldamin (2) inklusive der entsprechenden Kupfer(II)-KomplexeI undII dargestellt. VonI undII wurden die Kristallstrukturen ermittelt. KomplexI kristallisiert im triklinen System mita=10.804(5),b=12.589(5),c=10.369(3) Å, =107.72(3), =95.75(3) und =76.32(4)° in der Raumgruppe P mitZ=2. VerbindungII kristallisiert ebenfalls im triklinen System mita=10.718(2),b=13.861(4),c=10.110(9) Å, =95.99(2), =90.16(2) und =93.90(2)° in der Raumgruppe P mitZ=2. Die Geometrie rund um Cu ist in beiden Komplexen quadratisch-planar.

     

Thermal Studies of Copper(II) Squarate Complexes of Diamines in the Solid State

CuL₂C₄O₄ [L=ethane-1,2-diamine (en)], CuL₂C₄O₄⋅2H₂O [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten),N-propylethane-1,2-diamine (pren), N-methyl-N’-ethylethane- 1,2-diamine (meeten) andpropane-1,2-diamine (pn)], CuL₂C₄O₄⋅0.5H₂O [L=N,N’-dimethylethane- 1,2-diamine (dmeen)], CuL₂C₄O₄⋅4H₂O [L=propane-1,2-diamine (pn)]and CuL₂C₄O₄⋅H₂O[L=2-methylpropane-1,2-diamine (ibn)] have been synthesized by the addition of respective diamine to finely powdered CuC₄O₄⋅2H₂O and their thermal studies have been carried out in the solid state. Cu(en)₂C₄O₄ upon heating loses one molecule of diamine with shar pcolour change yielding Cu(en)C₄O₄ which upon further heating transforms to unidentified products. All aquated-bis-diamine species [CuL₂C₄O₄⋅2H₂O, CuL₂C₄O₄⋅0.5H₂O and CuL₂C₄O₄⋅H₂O] upon heating undergo deaquation–anation reaction in the solid state showing thermochromism and transform to CuL₂C⁴O₄, which revert on exposure to humid atmosphere (RH ∼90%). All the squarato bis-diamine species, CuL₂C₄O₄, on further heating transform to unidentified products through the formation of CuLC₄O₄ as intermediates. The mono diamine species, have been isolated pyrolytically in the solid state and can be stored in a desiccator as well as in open atmosphere. They are proposed to be polymeric. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pendant-Arm Macrocycles Derived from the Cyclocondensation Reaction of Sodium 2,6-Diformyl-4-substitutedphenolates and Tris-(2-aminoethyl)amine Derivatives. Preparation, Characterization and Properties of their Dinuclear Copper(II) Complexes

A series of pendant-arm Schiff base macrocycles have been obtained via the cyclocondensation reaction between sodium 2,6-diformyl-4-substitutedphenolates and tris-(2-aminoethyl)- amine derivatives followed by transmetallation with Cu(ClO₄)₂·6H₂O. The resulting dinuclear copper(II) complexes have been characterized by elemental analysis, infrared and mass spectra as well as magnetic moments at room temperature. All complexes have been electrochemically investigated, and two typical compounds have been studied with ESR spectra as well.     

The structures and cyclic voltammetry of three copper(II) complexes derived from bulky ortho-hydroxy Schiff bases

Three copper(II) complexes derived from bulky ortho-hydroxy Schiff base ligands, (1)-(3), were synthesized and characterized by chemical analysis, UV-Vis, IR, μ_eff and mass spectrometry. The solid state structures of compounds (1)-(3) were determined. The solid state X-ray diffraction studies of these compounds show that the geometry is intermediate between square planar and tetrahedral. Moreover, EPR studies in DMF solution at 77 K suggest that the geometry of these complexes in solution is different from that observed in the solid state by X-ray crystallography. Furthermore, cyclic voltammetry studies performed for (1)-(3), indicate a dependence of the cathodic potentials upon conformational and electronic effects.     

Synthesis and Characterization of New Macrocyclic Cu（Ⅱ） Complexes from Various Diamines, Copper（Ⅱ） Nitrate and 1,4-Bis（2-formylphenoxy）butane

Six new macrocyclic complexes were synthesized by a template reaction of 1,4-bis（2-formylphenoxy）butane with diamines and Cu（NO3）2·3H2O and their structures were proposed on the basis of elemental analysis, FT-IR, UV-Vis, magnetic susceptibility measurements, molar conductivity measurements and mass spectra. The metal to ligand molar ratios of the Cu（Ⅱ） complexes were found to be 1 ： 1. The Cu（Ⅱ） complexes are 1 ： 2 electrolytes as shown by their molar conductivities （∧m） in DMF at 10^-3 mol·L^-1. Due to the existence of free ions the Cu（Ⅱ） complexes are electrically conductive. Their configurations were proposed to be probably distorted octahedral.     

Synthesis,Spectroscopic and Electrochemical Studies of Novel Transition Metal Complexes with Quadridentate Schiff Base

A novel quadridentate, N₂O₂ type Schiff base, synthesized from 1,4‐bis‐(o‐aminophenoxy)butane and 2‐hydroxynaphthalin‐1‐carbaldehyde, forms stable complexes with transition metal ions such as Co(II), Cu(II) and Ni(II) in DMF. Microanalytical data, elemental analysis, magnetic measurements, UV‐visible and IR‐spectra as well as conductance measurements were used to confirm the structures. Electrochemical measurements show that metal complexes undergo quasi‐reversible one‐electron redox processes. The voltammetric results also revealed that the CuL complex has the highest electron transfer rate indicating that both the Cu(II) and Cu(I) forms appear in a similar planar configuration, so the electron transfer does not require larger reorganization of the complex.     

具有三维结构的Co(II)配合物二阶非线性光学性质的DFT研究

以实验合成出的Schiff碱配体和Co(II)配合物为母体,设计了Schiff碱配体和具有三维结构的Co(II)配合物.采用密度泛函理论的B3LYP/6-31g(d)-FF方法对具有开壳层电子组态Co(II)配合物及相应配体的二阶非线性光学(NLO)效应进行了计算.结果表明:Schiff碱配体形成配合物后分子的二阶NLO性质没有发生大的改变,这是由于金属Co2 离子在配合物电荷转移(CT)过程中起到了桥的作用,对分子的二阶NLO响应直接贡献不大.结合配合物的前线分子轨道分析发现,在分子内电荷转移过程中,对分子二阶NLO系数的主要贡献是配体内电荷转移(ILCT)跃迁.     

Syntheses,Crystal Structures,and Magnetic Properties of Carboxylate-Bridged Copper(II) Complexes with Bis(2-Pyridylmethyl)Amino Acids

Tetradentate Schiff-base carboxylate-containing ligands, bis(2-pyridylmethyl)amino-5-valeric acid (Hpmva) and bis(2-pyridylmethyl)amino-6-caproic acid (Hpmca), react with copper(II) perchlorate to give rise to the carboxylated bridged chain complexes {[Cu(μ-pmva)(H₂O)](ClO₄)}_n (1) and {[Cu(μ-pmca)(H₂O)](ClO₄)}_n (2). These complexes have been characterized by X-ray crystallography, spectroscopic, and variable-temperature magnetic susceptibility measurements. In 1 and 2, each of the copper(II) ions exhibit CuN₃O₂ coordination environments with the three nitrogen atoms of the ligand and one oxygen atom belonging to the carboxylate group of an adjacent molecule occupying the basal position and a water molecule coordinated in the axial position. The electronic spectra of the complexes are significantly affected by the coordination geometry. Magnetic susceptibility measurements indicate that complexes exhibit very weak ferromagnetic interactions.     

Studies on Phenol Oxidation with H2O2 Catalyzed by Schiff Base Cobalt(II) Complexes in Micellar Solution

The two Schiff base cobalt(II) complexes, CoL¹ and CoL², were synthesized and characterized. The metallomicelle made up of the cobalt(II) complexes and surfactants (CTAB, LSS and Brij35), as mimic peroxidase metalloenzyme, were used in the catalytic oxidation of phenol by H₂O₂. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were studied. The acid effect of reaction system, structural effect of the complexes, and effect of temperature on the rate of the phenol oxidation catalyzed by the mimetic peroxidases have been discussed. The results showed that the schiff base cobalt(II) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.     

EPR Spectra of Copper(II) Complexes with N,N-Dialkyl Amino Acids. The Influence of Water dissolved in Organic Solvents on the Copper(II) Coordination Sphere

EPR spectra of four bis(N,N-dialkyl-L-α-aminoacidato) copper(II) complexes were studied with the aim to determine the effect of the water molecules dissolved in organic solvents on the electronic states of copper(II). It was shown that water dissolved in methylene chloride or dioxan influence the copper(II) electronic states. If the amino acid side chains are long enough to form the aliphatic intramolecular van der Waals contacts, the water molecules will induce the change in the conformation of the whole complex.     

含氮配体Co、Fe配合物的合成、结构及性质

报导了四个单核Co（Ⅱ）和Fe（Ⅱ）的配合物[Co（L1）2]（ClO4)2·（CH3CN）（1）,[Fe（L1）2]（ClO4）2·（H2O）（2）,[Co（L2）]（ClO4）2（3）,以及[Fe（L2）]（ClO4）2·2H2O（4）,（其中L1＝4’-苯基-2,2’：6’,2”-三联吡啶,L2＝N,N,N-三-（2-（2-吡啶甲叉氨基）乙基）胺）的合成和性质,以及配合物1、3的晶体结构．配合物1和3的晶体都属于单斜晶系．它们的晶胞参数分别为：1a＝1．0855（4）nm,b＝1．6201（5）nm,c=2.5236（5）nm,β＝92．63（2）°,V＝4．433（1）nm3;3a=2.8351（8）nm,b＝1．0670（3）nm,c＝1．9255（5）m,β＝101．03（4）°,V＝5717（2）nm3．2和4的氧化还原电位分别为E＝0．78V和0．63V‘它们的d-d跃迁吸收最大值分别位于565和521nm处．     

Novel Isatin-Schiff Base Cu (II) and Ni(II) Complexes. X-ray Crystal Structure of Bis[3-(4-hexylphenylimino)-1H-indol-2(3H)-one]-dichlorocopper(II) Complex

Schiff bases of isatin were reported to possess antibacterial, antifungal, antiviral, anti-HIV, antiprotozoal, and anthelmintic activities1. They also exhibit significantanticonvulsant activity, apart from other pharmacological properties2. Conductingsubs…     

Spectroscopic Behaviour of Copper(II) Complexes Containing 2-Hydroxyphenones

Theoretical investigations by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods shed light on how the type of ligand or attached groups influence the electronic structure, absorption spectrum, electron excitation, and intramolecular and interfacial electron transfer of the Cu(II) complexes under study. The findings provide new insight into the designing and screening of high-performance dyes for dye-sensitized solar cells (DSSCs).     

Preparation and Thermal Decomposition of Copper(II) Complexes with 4-Methylimidazole

Simple and mixed compounds of the formulae Cu(4-Meim)₂, CuSal(4-Meim), CuSal(4-Meim)₂ and CuSalox(4-Meim)₂, where 4-Meim=4-methylimidazole, Sal=(OC₆H₄COO)²⁻, Salox=(OC₆H₄CHNO)²⁻ have been prepared. Thermal decomposition reactions have been established on the basis of thermal and X-ray analyses of these compounds. The pyrolysis proceeds in several (3–4) stages connected with the mass loss and exothermic effects. As a result of the last stage of decomposition CuO is formed. This revised version was published online in August 2006 with corrections to the Cover Date.