Copper(II) Chelate Complex with N′-(2,4-Dichlorophenoxy)acetyl-N,N-Dimethylhydrazine: Crystal and Molecular Structure

X-ray diffraction analysis of the copper(II) chelate complex CuL₂ (where L is the deprotonated imid-ol form of N,N-dimethyl-2,4-dichlorophenoxyacetohydrazide (HL)) was performed (3826 reflections, R = 0.039, wR = 0.043). Crystals are monoclinic, a = 8.365(7) Å, b = 23.090(7)Å, c = 12.713(3) Å, = 95.12(6)°, space group P2₁/c, Z = 4. The slightly distorted square environment of the copper cation is composed of two N atoms of the dimethylamino groups and two O atoms of the deprotonated imidol groups. Both N and O atoms are located in trans-positions relative to each other. Additional coordination of electron-donor atoms is prevented by methyl groups, in which the C atoms are at a distance of 2.837 to 2.918 Å from the central ion.     

Complexes of Some 3d-Metal Salts with N,N-Dimethylhydrazide of 4-Nitrobenzoic Acid

The [M(HL)₂(H₂O)₂]X₂ complexes were synthesized (M = Mn(II), Co(II), Ni(II), Cu(II), Zn; X = CH₃COO^–, Cl^–, BF₄ ^–) that incorporate bidentately coordinated molecules of N,N-dimethylhydrazide of 4-nitrobenzoic acid (HL). The latter molecules chelate the metal atom through the carbonyl O atom and the N atom of dimethylamino group. The square-planar complexes of Cu and Ni with deprotonated form of a ligand with composition ML₂ were also isolated. The synthesized complexes were studied by IR, electronic and EPR spectroscopies, and by cyclic voltammetry.     

Kinetics and mechanism of oxidation of copper(I) ions with thiuram disulfide

The kinetics of the oxidation of copper(I) perchlorate with thiuram disulfide (tds) in acetonitrile and its mixtures with benzene or ethyl bromide have been investigated. It has been shown that the rate of the reaction is limited by the inner-sphere transfer of an electron from the copper(I) ion to tds in a complex of the type [Cu^I(tds)]⁺. The subsequent dissociation of the anionradical tds —proceeds rapidly and leads to the formation of copper(II) dithiocarbamate which is recorded in the absorption spectra and by EPR. The rate constant of electron transfer has been determined (3·10^–4sec^–1) and it was found that it is practically independent of the polarity of the medium. The absence of such a correlation is attributed to the negligible energies of reorganization of the solvent in the inner-sphere electron transfer.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 4, pp. 450–455, July–August, 1988.     

Matching the nanoporous carbon electrodes and organic electrolytes in double layer capacitors

In order to see how the power density of supercapacitors could be increased, a theoretical model of the nanoporous carbon electrode as a tier structure with transport channels has been developed. Also an experimental method has been developed to measure the rate of electrolyte transport through the porous electrode material. This method can be used for quick analysis and selection of electrodes. The results of modeling have been verified by testing the experimental EDLC prototypes with optimum electrode thickness and electrode porosity, the porosity being well matched with the size of ions in organic electrolytes. This enables us to reach a power density as high as 6–7 kW/L with a reasonably large energy density and high efficiency for both EDLC unit cells and stacks. PACS 82.47.Uv     

Kinetics of the growth of the oxide layer during anodic oxidation of aluminum

Experimental plots of anode current density against time obtained for various electrolytes over a temperature range from 5 to 60°C have been compared with a theoretical model which describes the kinetics of the growth of the oxide film during anodic oxidation of aluminum. It is concluded from differences in the kinetic parameters for ammonium benzoate and ammonium adipate that the oxidative destruction of the corresponding carboxylate anion is involved in a rate determining step of the process. V. I. Vernadskii Institute of General and Inorganic Chemistry, Ukraine Academy of Sciences, 32/34 Academician Palladin Prosp., 252680 Kiev-142, Ukraine. Translated from Teoreticheskiya i éksperimental’naya Khimii, Vol. 33, No. 1, pp. 58–61, January–February, 1997.     

Kinetics and mechanism of electron transfer via bridge metal-ion

The kinetics and mechanism of electron transfer between stable verdazyl radicals via bridge Mn(II), Co(II), Ni(II), Cu(I), and Zn ions have been studied in the range 280–330 K using the stopped-flow technique. It was found that the kinetic features of the reactions could be described in terms of the Marcus theory. The reorganization energy of the inner coordination sphere (ICS) of intermediate complexes was estimated from the reported data on the energy of release of various ligands from the ICS of similar complexes. The rest of the kinetic parameters (solvent reorganization energy, transmission coefficients, enthalpy, and entropy of activation) were determined from Marcus equations and from plots of rate constant versus temperature, “standard” free energy, and polarity of the medium. It was also found that the reactions under consideration are nonadiabatic and the transmission coefficient value depends on the mean lifetimes of ligands in the ICS.     

Energy Storage Technologies Based on Electrochemical Double Layer Capacitors: A Review

Theoretical and Experimental Chemistry - Modern design approaches to electric energy storage devices based on nanostructured electrode materials, in particular, electrochemical double layer...     

Model of oxide film growth during anodization of aluminum

A theiretical model is proposed for describing the growth of an amorphous or polycrystalline oxide film on an aluminum surface during its anodization. an example of anodization in electrolytes based on salts of dicarboxylic acids is used to illustrate a satisfactory agreement of the model with the experimental data.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 5, pp. 272–276, September–October, 1994.     

Dissociative electron transfer reactions

We consider recent data on dissociative electron transfer reactions in which the electron transfer causes practically concerted dissociation of the chemical bond in the reagent. We discuss considerable experimental data on reactions in the gas phase and in solutions, and also existing theoretical models for describing the kinetics of these complex processes. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 67–78, March–April, 1998.     

Activation parameters of electron-transfer reactions with synchronous cleavage of a bond

The temperature dependence of the rate constants of the disproportionation reactions of verdazyl radicals (R') in their complexes with zinc ions and of the inner-sphere oxidation of copper(I) by tetraethylthiuram disulfide (tds) in acetonitrile and mixtures of the latter with benzene has been measured. The activation parameters of the reactions studied have been determined according to the Arrhenius equation. In these reactions electron transfer is accompanied by the synchronous cleavage of a chemical bond [Zn-R in the complex Zn(R')₂ ²⁺ or S-S in tds], which is manifested by a decrease in the value of the preexponential factor. It has been established that the dependence of the rate constants on the polarity of the medium does not conform to the framework of Marcus' theory, but the activation energy and the preexponential factor decrease symbatically and approximately exponentially as the mole fraction of the polar molecules of acetonitrile in its mixtures with benzene is increased.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 4, pp. 501–504, July–August, 1988.