Physical studies in the field of unsaturated aryl ethers and their derivatives

Conclusions Consideration of the foregoing results leads us to the following generalizations. The molecular wave functions of the mobile electrons are not localized on individual groups of atoms in the compounds under consideration, but belong to the molecule as a whole. The fact that the oxygen atom is linked to two unsaturated radicals leads to a considerable additional change in the density of the mobile electrons of this atom. The interaction of the p electrons of oxygen with each of these radicals, as expressed in the density distribution of the mobile electrons, is primarily determined by the nature of the particular radical, and apparently to a lesser extent by the nature of the second radical.An increase in the acceptor properties of one of the radicals leads to an increase in the calculated positive charge on the oxygen atom and in the order of the corresponding C–O bond. Changes in the order of the second C–O bond and the density distribution of the mobile electrons neighboring this bond are determined by weak composition for the p electron of the oxygen between the unsaturated groups to which this atom is attached.We may suppose that the change in the integral Raman-line intensity associated with the valence vibrations of the double bond and, possibly, the oscillations of the benzene-ring framework (1600 cm^–1) in vinylaryl ethers is connected with the existence of a common system of mobile electrons and with variations in the polarizability of this system.The author finds it his pleasant duty to express sincere thanks to Professor N. A. Prilezhaeva of Tomsk University for help and valuable discussions.Translated from Zhurnal Strukturnoi Khimii, Vol. 7, No. 3, pp. 417–427, May–June, 1966     

Dehydration kinetics of ulexite from thermogravimetric data

In the present study, the kinetic parameters of the thermal decomposition of ulexite were investigated by using TGA data. For the kinetic analysis, the Suzuki and Coats-Redfern methods were applied. It was determined that the process fits a first-order kinetic model, and the value of the activation energies and frequency factors decreased with decreasing particle size, which can be attributed to the increasing particle internal resistance to the escape of water as the grain size increases. The activation energy values were found to be 47.34–60.01 kJ mol^–1 for region I and 0.225–1.796 kJ mol^–1 for region II for the range of particle size fraction used. The frequency factors were calculated to be 9821.8–524.9 s^–1 for region I and 3.05×10^–44–2.807×10^–5 for region II for the same conditions.     

Structural and electronic properties of lithium ion battery anode material LiMN (M = Ni, Co, Cu)

The structural and electronic properties of anode materials LiMN (M = Ni, Co, Cu) for lithium ion batteries have been studied by the first-principles method. The calculations reveal different bonding characteristics for LiMN (M = Ni, Co, Cu). The Li–N bond on the LiN planes shows covalent mixed with ionic characters, with the covalent interaction strengthened and ionic one weakened gradually from LiNiN to LiCoN and then to LiCuN. In the direction of N–M chains, the bonding characteristics are analogous on the whole. The N–M bonding shows both ionic and covalent characters again, while the covalent interaction slightly weakened in sequence. Electronic structure calculations suggest that LiMN (M = Ni, Co, Cu) are all metallic, where the LiNiN is of anisotropic conductivity along the directions of N–Ni chains, while for LiCoN and LiCuN, electrons can also be feebly conductive on the LiN planes besides along the linear N–Co and N–Cu chains.     

On the mechanism of formation of intratrack yields of water radiolysis products upon irradiation with fast electrons and positrons: 1. Model formulation

A mathematical model is constructed for the formation of main transient (e _aq ^– , H, OH) and final (H₂, H₃O⁺, OH^–, Ps) radiolytic products formed in tracks of fast electrons and positrons in water and aqueous solutions. The model takes into account the occurrence of reactions of epithermal electrons, along with thermal and hydrated electrons, with a solute; the ambipolar character of diffusion of charged intratrack particles; and new pathways of the formation of hydrogen and positronium due to the appearance of weakly bound adducts of electrons with their scavengers, in addition to the traditional routes.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 3, 2005, pp. 165–170.Original Russian Text Copyright © 2005 by Stepanov, Byakov.     

Vibronic reduction of Heisenberg and double exchange in multielectron mixed-valency clusters

Vibronic reduction is considered for Coulomb interaction between centers for Heisenberg and double exchange in multielectron mixed-valency d²-d³ clusters. A simplified multimode vibration model indicates how effects arise via vibrations from the correlation interaction between electron shells. Vibronic reduction in double exchange can alter the magnetic parameters for the cluster's ground state.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 2, pp. 114–121, March–April, 1992.     

The enthalpy and entropy interaction parameters of cesium chloride with saccharides ( -glucose, -fructose and sucrose) in water at 298.15 K

The transfer enthalpies have been measured for cesium chloride from pure water to aqueous saccharides ( -glucose, -fructose and sucrose) solutions at 298.15 K. The McMillan–Mayer theory was employed to relate the excess thermodynamic function with a series of interaction parameters of solutes to obtain the enthalpy pair interaction parameters of cesium chloride with saccharides in water. Entropy interaction parameters can be evaluated through the enthalpy interaction parameters and the Gibbs free energy parameters. These parameters are discussed in detail to provide some information for the interaction of solute–solute and solute–solvent in CsCl–saccharide–water ternary system, and to investigate the influence of the size of metal ions and the number of hydroxyl in saccharides on these parameters.     

Quantum chemistry of the bipolaron in an isotropic continuous medium

We consider the electronic wave functions and binding energy of the bipolaron, which is a bound state of two electrons in an ionic crystal. The system is considered in terms of a model resembling the helium atom or hydrogen molecule, where the role of the attractive Coulomb potentials of the nuclei is played by polarization potential wells calculated in the macroscopic approximation. The importance of correlations in the motion of the electrons in the bipolaron is demonstrated. An existence criterion for the bipolaron is established and its binding energy and characteristic size is determined. We also consider quasimolecules formed in a polarizable medium from like-charged particles of different masses (such as an electron plus a^– meson).Deceased.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 6, pp. 641–647, November–December, 1989.     

Electrolyte mixing thermodynamics to probe ion-ion interactions

In their study of solvent-averaged ion-ion pair potentials, Pettitt and Rossky show that, at least for the given underlying Born-Oppenheimer level model, there is a remarkable well in the potential of the solventaveraged Cl^––Cl^– interaction in water; it has a minimum below-kT and near 3.6Å, the Pauling diameter for the Cl^– ion. As Pettitt and Rossky also showed, the osmotic coefficient of aqueus NaCl solution as a function of ionic strength (I) could be insensitive to this remarkable feature, even when the well implies that there is a substantial concentration of dimers at 1M or higher stoichiometric concentration. Here it is argued that the thermodynamics of mixtures of aqueous NaCl with, say, aqueous NaClO₄, should be sensitive to the presence of the well in the Cl^––Cl^– interaction. Accordingly we apply the HNC approximation to calculate the mixing coefficients that characterize the excess free energy functions of several model aqueous NaCl–NaClO₄ mixed electrolyte solutions. For reference we use a model (V₆) in which all six ion-ion pair potentials have the simple vanilla form: charged soft spheres supplemented by a dielectric image correction and an adjustable Gurney term that represents an interaction of the solvation structures about the ions. The six Gurney coefficients were adjusted to tune the model (I) close to the experimental for pure NaCl, pure NaClO₄, and an equimolar mixture, all in the range 0.1I2M. We find that the V₆ model gives mixing coefficients that agree closely with experiment. The calculations were also made for five models that incorporate, in varying degrees, the Pettitt-Rossky pair potentials. Comparison of the mixing coefficients for these models with the experimental data leads to the conclusion that the Cl^–, Cl^– well is unrealistic, although a shallower well in the same place might be acceptable.     

Quantum-chemical modeling of photoelectron spectra and electronic structure of <Emphasis Type="Italic">tris</Emphasis>-β-diketonates of 3<Emphasis Type="Italic">d</Emphasis>-metals Sc,Ti, V

The electronic structure and ionization energies of chelate complexes were calculated for transition metals Sc, Ti, and V using the Hartree-Fock (HF)SCF ab initio approximations. As the number of d electrons increases in the series of these compounds, the sequence of HF orbitals does not agree any longer with the PES bands and with the data obtained in the density functional theory approximation. Using the configuration interaction (CI) method considerably improves agreement with experiment. For the vanadium complex containing an odd d electron in the ionized state, the HF orbitals become a rough approximation for the CI decomposition, hindering the interpretation of the ionic states.Original Russian Text Copyright © 2004 by V. I. Vovna and I. S. OsmushkoTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 651–659, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Criteria of asymmetry of the electron density distribution of polymethine dyes with several chromophores

The absorption and fluorescence spectra of 6-B-thia- and 6-B-imidathiadimethinemerocyaninocyanines were investigated. It was established that the transition from absorption spectra to fluorescence spectra leads to an underestimation of the deviations. The influence of resonance interaction of the chromophores on the value of the deviations of the long-wave absorption and fluorescence bands of dyes with two chromophores is discussed. It was shown that resonance interaction leads to a decrease in the contribution to the deviation from alternation of the bonds in the polymethine chromophore and an increase in the topologic component of the deviation. A new criterion of asymmetry of the electron density distribution in dyes with several chromophores is proposed.Translated from Teoreticheskaya i Éksperimental'naya, Khimiya, Vol. 21, No. 6, pp. 641–650, November–December, 1985.     

Interactions of HCl with 1-Butanol and Group Additivity Analysis for the HCl–Alcohol Interactions

An electromotive force (emf) method was used to determine thermodynamic parameters of interaction of HCl with normal 1-butanol (n-BuOH) in water between 5 and 45°C. A comparison of pair interaction parameters for HCl–n-BuOH with those for HCl–t-BuOH (tert butyl alcohol) showed that there is an obvious difference between them. This was interpreted in terms of steric structure of their carbon chains. The group Gibbs free energy parameters ( and ) for the HCl–alcohol–water systems were derived according to the Savage–Wood group additivity principle. These group parameters can be used to evaluate pair interaction parameters of HCl with alcohol molecules.     

A consistent approach to construction of the model valence electron hamiltonian: M2, M = Li,Na, K,Rb, Cs

A consistent procedure is considered for the development of a correct model Hamiltonian for many-electron diatomic molecules in the framework of the Rayleigh-Schrödinger perturbation theoy with zero approximation model potential and with corrections for the exchange-correlation effects as high order effects. Using the pseudopotential approach, we have calculated some molecular constants, in particular, the dissociation energy of homo- and heteronuclear diatomic alkaline molecules. It is shown that an accurate correction for the principal correlation effects (the polarization interaction of valence electrons via the polarized core and mutual screening of outer particles) is critical for obtaining a reasonable calculation accuracy. We suggest ways to improve the accuracy of calculations by using (in zero approximation of the perturbation theoy) reliable empirical information about simple systems, such as the M₂ ⁺ ions (M = Li, Na, K, Rb, Cs).Hydrometeorological Institute, Ukraine. Translated fromZhurnal Strukturnoi Khimii Vol. 34, No. 5, pp. 3–11, September–October, 1993.Translated by I. Zilberberg     

Molecular,thermodynamic, and kinetic parameters of iodomethanes and iodomethyl radicals: <Emphasis Type="Italic">ab initio</Emphasis> calculations

The wave functions and enthalpies of formation of the ground states of iodomethanes CH_{4– x} I_x and iodomethyl radicals CH_3–x I_x. (x = 1–3) were calculated ab initio with regard to electron correlation. The geometries of the molecules of these compounds were determined, as well as the normal mode frequencies and other parameters, which were used for calculating the thermodynamic functions in the 0–1500 K range. These functions were used for calculating the constants of the CH_4–x I_x CH_4–x I _x–1 + I and CH_4–x I_x + I CH_{4– x} I _x–1 + I₂ equilibria, which, in turn, were used for calculating the corresponding rate constants in the high concentration limit.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1812–1822.Original Russian Text Copyright © 2004 by Dymov, Skorobogatov, Tschuikow-Roux.This revised version was published online in April 2005 with a corrected cover date.     

Investigation of complexes of DNA with synthetic peptide fragments of the N-end of histone H2B

The nature of the interaction of high- and low-molecular-weight DNAs (6×10⁶ and 3×10⁵ daltons) with synthetic oligopeptides of the N-end of histone H2B having the sequences 1–21, 1–10, 1–13, 11–21, and 14–21, differing in molecular weight and amino acid composition, as a function of the amount of peptide component in the complex and the ionic strength of the solution has been studied by the methods of UV and CD spectroscopy and the spectrophotometric analysis of melting curves. It has been shown that of all the peptides studied only the 1–21 peptide possesses the capacity of condensing DNA. This capacity depends on the amount of peptide component in the complex, the molecular weight of the DNA, and the ionic strength of the solution. The interaction with peptides under all the conditions studied, without changing the conformational parameters of the DNA, stabilizes its secondary structure in relation to the action of the temperature, which depends on the number of lysine residues in the peptides.N. I. Nikitin Institute of Chemistry of the TadzhSSR Academy of Sciences, Dushanbe. Institute of Cytology of the USSR Academy of Sciences, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 708–713, September–October, 1987.     

Polymethine-polyene transition parameter in polymethine dyes

Within the framework of the HMO approximation and an equal bond model, quantitative characteristics are proposed for the alternation of electron density on the atoms and bonds of an unsubstituted chain of polymethine dyes with arbitrary end-groups. These characteristics can be used, depending on the type of electron distribution, to classify a compound as a polymethine or polyene. A structural parameter determined by the nature of the end-groups has been found, this parameter being responsible for realization of one type of electron density distribution or the other in the polymethine chain.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 2, pp. 129–138, March–April, 1988.     

Quasi-relativistic study of electronic structure of uranium tetrafluoride

Conclusions A comparison of the results obtained in a calculation of the electronic structure of UF₄, performed in the NR and QR approximations of the X-SW method, leads to a number of conclusions as to the role of relativistic effects in the electronic structure of molecules. a) An accounting for relativistic effects leads to changes in the spatial distribution of charge in the molecules and to a consequent change in the interpretation of the bond in terms of the ratio of ionic and covalent components. b) Relativistic compression of the wave functions of the s and p electrons (primary relativistic effects) and delocalization of the d and f functions (secondary relativistic effects) lead to substantial changes in the orbital energies and the corresponding ionization potentials in heavy molecules. c) Primary and secondary relativistic effects are responsible for considerable changes in the electronic excitation energies and the EA, changes that may account to as much as 200%. d) An accounting for spin-orbit interaction effects is extremely important in interpreting photoelectron and optical spectra. In the example of UF₄, it has been shown that NR wave functions are inadequate for use in calculating spin—orbit splittings in heavy molecules. Just as inadequate may be an accounting for spin—orbit interaction in first-order perturbation theory for systems of closelying MOs, the charge density of which is determined to a considerable degree by AOs of a single type (for example, 5f AOs of uranium in UF₄).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 20, No. 4, pp. 406–415, July–August, 1984.The authors wish to express their appreciation to M. I. Timokhin for assistance in performing the calculations.     

Effect of the noncoordinated nitrogen atoms in the macroring on the spin equilibria of nickel(II) complexes with penta- and hexaazamacrocygles: new type of ditopic receptors for hydrosulfate anions

For the first time it was observed that nickel(II) complexes with 14-membered macrocyclic ligands that contain additional noncoordinated nitrogen atoms in the macroring exhibit high selectivity with respect to tying up hydrosulfate anions in acidic aqueous solutions. This effect is explained by a specific two-center interaction of the complex with the anion due to the formation of a donor-acceptor bond with the nickel ion and a hydrogen bond with the unshared pair of electrons of the noncoordinated nitrogen atom.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, Nos. 5–6, pp. 436–441, September–December, 1992.     

Interaction of gallium, indium, thallium, germanium, tin, and lead with boron

Summary Investigations of the interaction of boron with gallium, indium, thallium, germanium, tin, and lead with boron showed that these elements do not form chemical compounds or solid solutions with boron.The absence of any interaction between these elements and boron is explained in the light of a discussion of the electronic structure and energy characteristics of the valence electrons of metals of the IIIB and IVB subgroups of the periodic system.Translated from Zhurnal Strukturnoi Khimii, Vol. 1, No. 4, pp. 458–463, November–December, 1960     

Formation of negative ions by interaction of electrons with heterocyclic compounds

Curves are derived for the effective yield of negative ions from the interaction of electrons with thiophene, 2-methylthiophene, 2-propylthiophene, 3-methylthiophene, 3-propylthiophene, furan, and selenophene. It is found that there are two quasi-stationary states of the molecular negative ions having lifetimes of about 10^–14 and 4 · 10^–15 sec. The cross sections for formation of these states are estimated, and also the cross sections for resonant elastic scattering of electrons. The states are shown to be related to excited states of the molecule. It is found that alkyl substitution has the following effects on resonant electron capture: a) reduces the probability of ring breakage and b) reduces the energy levels of the quasi-stationary state. Some aspects of dissociative ionization are discussed.     

Long-range molecular interaction coefficients computed from frost-model wave functions

The average long-range interaction energy between two molecules can be written as an inverse asymptotic series in the intermolecular separation distanceR. Using Frost-model wave functions, the dispersion coefficients of the first three (R ^–6,R ^–8,R ^–10 terms in the series are obtained. Coefficients of three- and four-body non-additive interaction energies are also calculated and the form of the dispersion interaction when retardation effects are included is examined.