Spontaneous raman spectroscopic study of the association of liquid γ-butyrolactone molecules

Self-association of γ-butyrolactone molecules in pure liquid state and in nonpolar solutions is studied by spontaneous Raman spectroscopy. The constant and the enthalpy of formation of cyclic dimers in liquid γ-butyrolactone are calculated. Ufa State Aircraft Technical University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 6, pp. 1099–1103, November–December, 1996. Translated by L. Smolina     

Structural,vibrational, and energy characteristics of halide molecules of group II–V elements

Correlations between the internuclear distances r(M-X), the bond energies E(M-X), and the valence force constants f_r for di- and trihalides of Group II–V elements are established. Some missing values are estimated. Ivanovo State Chemical Technological Academy. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 5, pp. 859–875, September–October, 1996. Translated by L. Smolina Ivanovo State Chemical Technological Academy. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 5, pp. 859–875, September–October, 1996.     

Vibrational structure of the electron transition to the second excited singlet state of pyridine N-oxide

The vibrational structure of the electron transition to the second singlet excited state of pyridine N-oxide has been studied. The frequency of the 0–0 transition is 34502 cm⁻¹. A computer-aided technique for the assignment of the frequencies of the normal vibrations of polyatomic molecules in the excited electronic states is proposed. The frequencies of the totally symmetric vibrations of pyridine N-oxide in the second singlet electronically excited state are assigned. N. G. Chernyshevskii Saratov State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 350–355, March–April, 1995. Translated by I. Izvekova     

Topological analysis of the structure-mesomorphous property ralationship

The use of topological indices to reveal the relationship between molecular structure and mesomorphous properties is discussed. Mathematical models for classification of mesophase types are proposed. The effect of molecular structure and attractive ability on phase transition temperatures is described. Examples of using correlation equations to predict the properties of 2,5-disubstituted 1,3-dioxanes are given. A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 4, pp. 53–60, July–August, 1994. Translated by L. Smolina     

Analytical approximation of the conformational dependence of the exchange interaction parameters for axially coordinated Cu(II) complexes with nitroxides

Analytical expressions relating the exchange parameters to the geometrical characteristics that determine the position of the radical fragment >N−O in axially coordinated Cu(II) complexes are derived from the results of quantum chemical calculations. The contributions of the delocalization (major) and direct (minor) mechanisms are considered. The expressions are tested by application to some complexes with known geometrical structures. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk. Translated fromZhurnal Struktumoi Khimii, Vol. 36, No. 1, pp. 27–33, January–February, 1995. Translated by I. Izvekova     

Vibrational spectra of volatile inorganic hydrides in the liquid state

The results of studies of IR and Raman spectra of volatile inorganic hydrides of Group IV–VI and Periods 3 and 4 elements in the liquid state are surveyed and analyzed. The mechanisms of intermolecular interactions in these liquids are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 629–644, April, 1999.     

Equations of structure for valent crystals and the local valency balance

Physical principles underlying the local valency balance rule are discussed. It is shown that crystal stability does not obey the rule. Some more general rules of valent crystal structures are considered, and the corresponding equations, including Pauling's rules for one-aniont crystals as a particular case, are given. The equations may be used for analyses and predictions of complex structures. St. Petersburg State Technical University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 4, pp. 717–723, July–August, 1995. Translated by L. Smolina     

Effect of the form of tetrahedral radicals on silicate structures

In published structures of amphiboles and pyroxenes, the edge lengths of octahedral faces, approximately parallel to (100), are compared. The degree of distortion of octahedra is inversely proportional to the value of the SiOSi angle. Extrapolation of the degree of distortion to zero gives an equilibrium value of 145° for the angle. This value was obtained for amphiboles of varying composition and for six pyroxenes at different temperatures. This result confirms the previous conclusion that the structures tend to form SiOSi and AlOSi angles of 144–148° and 136–139°; other structural features, especially the limited availability of ternary tetrahedral rings in silicate radicals, are also evidence of this tendency. Irkutsk State Pedagogical Institute. Translated fromZhurnal Strukturnoi Khimii, Vol 35, No. 5, pp. 105–108, September–October, 1994. Translated by L. Smolina     

To the theory of electron scattering by polyatomic molecules

Within the Born-Oppenheimer adiabatic perturbation theory, an equation was obtained for the intensity of fast electron scattering by polyatomic molecules. All of its parameters are explicitly defined by vibronic interaction in a molecule; due to this, quantum chemical calculations are fully applicable to electron diffraction studies of molecular geometries. Engels Anti-Aircraft Missile Higher Military School. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 2, pp. 40–45, March–April, 1994. Translated by L. Smolina     

Group-theoretical classification of the resonance states of mixed-valence clusters

Moldova State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 4, pp. 743–747, July–August, 1995.     

Topology of polyhedral calthrate frameworks. 1. Relationships between basic topological characteristics of regular frameworks

The relations between the numbers of nodes, bonds, cycles, and polyhedral voids in regular tetrahedral frameworks formed of space-filling polyhedra are analyzed. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 884–890, September–October, 1995. Translated by L. Smolina     

Isothermal compressibility and correlation radius near the critical point: Numerical analysis of the Ornstein-Zernike equation

Solution of the Ornstein-Zernike equation is analyzed numerically in the Percus-Yevick and hyperchain approximations for a system of Lennard-Jones particles in a critical region. The temperature dependences of correlation functions, isothermal compressibility η, and correlation radius of density fluctuations ζ are investigated at a critical density; the corresponding critical indices are determined. It is shown that the Percus-Yevick approximation yields satisfactory results when the correlation functions are calculated within a range corresponding to approximately 50 atomic (molecular) diameters. In this case, with ≈5% deviations from the critical temperature, the calculated and experimental values of η and critical indices are in good agreement. Tver State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 799–807, September–October, 1995. Translated by I. Izvekova     

Electronic absorption spectrum of pyridine N-oxide in the gas phase. General characterization

The full electronic absorption spectrum of pyridine N-oxide vapor in the near ultraviolet region has been obtained. The vibronic structure has been analyzed in detail. The four absorption bands, which are observed at 341, 290, 228, and 217 nm, correspond to four 0–0 vibronic transitions. The spectrum is interpreted in terms of the CNDO/S method. The symmetry of the vibrations that exhibit activity due to the Herzberg-Teller effect in different electronic states has been studied. N. G. Chernyshevskii Saratov State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 345–349, March–April, 1995. Translated by I. Izvekova     

Estimation of the densities of solutions using the geometrical parameters of their component molecules

A new model based on certain physical concepts of interatomic interactions is proposed for simulating the volume characteristics of molecules that allow reliable estimations of the densities of substances and solutions. The model is used to calculate the solution densities for six substances within wide concentration ranges. Chelyabinsk State University. Translated fromZhurmal Strukturnoi Khimii, Vol. 36, No. 5, pp. 823–827, September–October, 1995. Translated by I. Izvekova     

Optical dissymmetry in crystals due to inhomogeneous distribution of isomorphous components

The mechanisms of optical dissymmetry (optical anomalies) due to inhomogeneous trapping of isomorphous impurities into a crystal are considered using water-soluble systems of potassium dihydrophosphate-ammonium dihydrophosphate and alum as an example. St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 5, pp. 60–69, September–October, 1994. Translated by L. Smolina     

Variational method for calculating the anharmonic vibrations of polyatomic molecules using a combined morse-anharmonic basis taking into account the fragmentary structure of molecules

A method of variational solution of anharmonic vibration problems using a mixed Morse—anharmonic basis is proposed. The basis functions are the products of the Morse oscillator eigenfunctions for vibrations of peripheral bonds, the harmonic oscillator eigenfunctions for almost harmonic skeletal and deformation vibrations, and the anharmonic basis functions for essentially anharmonic skeletal and deformation vibrations. The anharmonic basis wave functions are taken as a linear combination of the Morse and harmonic oscillator eigenfunctions. The introduction of the combined Morse—anharmonic functions allows one to factorize the solution of a problem into a series of individual blocks according to the fragmentary structure of molecules. Volgograd Pedagogical University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 231–238, March–April, 1995. Translated by I. Izvekova     

Crystal-chemical mechanism in the fundamental absorption of MgO crystal

Correlations between structural, thermal, and optical properties of MgO are shown as linear dependences of the energy ε of the photons absorbed by the crystal on the enthalpy of sublimation ΔH of the crystal to molecules, atoms, ions, and electrons. This dependence holds true only if in different schemes of crystal sublimation the values of ΔH are calculated for the cell MgO rather than its formula unit. M. V. Lomonosov Moscow State University, Geological Faculty. IGEM, Moscow. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 2, pp. 283–288, March–April, 1996. Translated by I. Izvekova     

Calculation of normal vibrations of adenine and its deuterium-substituted analogs

The vibrational spectra of adenine and its deuterium-substituted analogs are calculated in the valence force field approximation. The frequencies and forms of normal vibrations of the molecule at 1700–300 cm^-1 are interpreted. Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 324–333, March–April, 1997.     

Proceedings of the 12th International Seminar on Intermolecular Interactions and Molecular Conformations

Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 771–774, September–October, 1995.     

Vibrational spectra and intramolecular dynamics of six-membered azacycles in the ground and excited states

The geometrical structure, force fields, and parameters of vibrational-rotational interaction of six-membered azacyclic compounds in the ground and excited states are estimated using the structural dynamic model of a polyatomic molecule. Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 2, pp. 345–349, March–April, 1997.