<Emphasis Type="Italic">Ab initio</Emphasis> study of aniline and <Emphasis Type="Italic">n</Emphasis>-propylamine associates with nitrobenzene and <Emphasis Type="Italic">m</Emphasis>-cresol

An ab initio (6-31G**) study of binary associates of aniline and n-propylamine with nitrobenzene and m-cresol has been carried out. The structures corresponding to the total energy minimum of the system have been found for the associates, and their geometrical and energy characteristics have been determined. Basic types of intermolecular interactions have been established, and their effects on the reactivity of the amino group have been investigated.Original Russian Text Copyright © 2004 by I. A. Novakov, V. V. Korolkov, A. I. Pavlyuchko, B. S. Orlinson, and L. A. GribovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 595–601, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis of nonequilibrium Ir<Subscript>x</Subscript>Re<Subscript>1-x</Subscript> solid solutions. Crystal structure of [Ir(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl]<Subscript>2</Subscript>[ReCl<Subscript>6</Subscript>]Cl<Subscript>2</Subscript>

Synthesis of five binary complex salts with an [Ir(NH₃)₅Cl]²⁺ complex cation is described. The counterions are [ReCl₆]^2–, [IrCl₆]^2–, [ReBr₆]^2–, and Cl^–. A polycrystal X-ray diffraction study has been performed for [Ir(NH₃)₅Cl]₂[ReCl₆]Cl₂, and its crystal structure has been determined. A series of Ir _x Re_1–x phases (0.5 x > 1) were obtained by reductive thermolysis. For the Ir-Re system, the history of the V/Z(x) dependence has been refined.Original Russian Text Copyright © 2004 by S. A. Gromilov, S. V. Korenev, I. V. Korolkov, K. V. Yusenko, and I. A. BaidinaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 508–515, May–June 2004.     

Interatomic interactions and electronic structure of NbSe<Subscript>2</Subscript> and Nb<Subscript>1.25</Subscript>Se<Subscript>2</Subscript> nanotubes

Atomic models of achiral NbSe₂ nanotubes are suggested. Band structure calculations have been performed to investigate the electronic structure and determine the parameters of interatomic interactions. The distribution of the density of states and pair bond occupancies of NbSe₂ nanotubes are analyzed in relation to the type of the atomic configuration and the tube diameter; the results are compared with the band structure of the 2H-NbSe₂ crystal. Calculations have been carried out on hypothetical superstoichiometric nanotubes with a formal composition Nb_1.25Se₂ as possible quasi-one-dimensional nanoforms of autointercalated niobium diselenide.Original Russian Text Copyright © 2004 by A. N. Enyashin, V. V. Ivanovskaya, I. R. Shein, Yu. N. Makurin, N. I. Medvedeva, A. A. Sofronov, and A. L. IvanovskiiTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 579–588, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Some structural peculiarities of formamide-water binary mixtures according to proton spin-spin relaxation data

The formamide-water system has been studied by the proton spin-spin relaxation method. The compositions of the resulting heterosolvates have been determined along with the stability constants on the mole fraction scale, and the relaxation efficiency coefficients.Original Russian Text Copyright © 2004 by I. V. Sukhno, V. Yu. Buzko, V. T. Panyushkin, and I. A. KovalevaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 748–750, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Quantum-Chemical Evaluation of the Protolytic Properties of Thiophenols

The enthalpies and free energies of proton affinity (PA) were calculated by the PM3 method for 27 thiophenoxide anions. For thiophenols, linear correlation has been found between the PAs and the values of pK _a measured by different authors in aqueous acetone, aqueous ethanol, and methanol media. The dependences found permit one to predict a priori the protolytic properties of thiophenols. The differential effects of aqueous ethanol media with different ethanol contents on thiophenol acidity were evaluated based on quantum-chemical data.Original Russian Text Copyright © 2004 by A. N. Pankratov and A. V. Shalabai__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 800–806, September–October, 2004.     

Quantum-Chemical Study of the Profiles of Reactions that Form Pyrrole Anion N-Adducts with CS<Subscript>2</Subscript> and CO<Subscript>2</Subscript>

The profiles of reactions leading to pyrrole anion N-adducts with CO₂ and CS₂ have been studied by the ab initio (RHF/6-31+G*, MP2/6-31+G*) and density functional (B3LYP/6-31+G*) methods. Addition of the pyrrole anion to the carbon disulfide molecule is accompanied by the appearance of a minimum corresponding to a pre-reaction complex. The transformation of the complex to the N-pyrrolyldithiocarboxylate anion occurs via a low activation barrier, which is due to repolarization of the C=S bonds. The profile of the reaction leading to the pyrrole anion N-adduct with CO₂ does not contain any intermediate stationary points throughout the whole route from reagents to products.Original Russian Text Copyright © 2004 by V. B. Kobychev, N. M. Vitkovskaya, I. L. Zaitseva, and B. A. Trofimov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 990–993, November–December, 2004.     

Self-organised poly[(ethynediyl)(arylene)(ethynediyl)silylene]/<Emphasis Type="Italic">N</Emphasis>-ethylcarbazole/polyphenylsilsesquioxane hybrid nanomaterials: photoconductivity and electro-optic response at telecommunication wavelengths

The photoconductivity and electro-optic response of a self-organised nanostructured poly[(ethynediyl)(arylene)(ethynediyl)silylene]/N-ethylcarbazole/polyphenylsilsesquioxane composite have been investigated with a cw diode laser at a wavelength of 1500 nm. For electric field 25 V µm^–1 and beam intensity 18 W cm^–2, the photosensitivity was 0.5 pS cm^–1 (W cm^–2)^–1. The dark conductivity was found to be much less than the photoconductivity and the composite shows photo charge generation at this wavelength. The value of the composite electro-optic coefficient is in agreement with data for polymeric materials active in the visible range. Orientational effects have been observed with modulation frequencies down to several Hz, and quite slow dynamics of the response can be expected.Based on the report presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (Moscow, May 30–June 4, 2004).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1897–1901, September, 2004.     

Quantum-Chemical Study of Structural and Energy Characteristics of Benzonitrile Dimers

Ab initio MP2 calculations with several basis sets proved the existence of a stable benzonitrile dimer with a planar structure and a short contact between the H atom of one molecule and the N atom of another. The structure is greatly stabilized by attraction between the neighboring oppositely directed dipoles and donor-acceptor interaction between the orbital of the lone electron pair of the N′ atom and the vacant antibonding orbital localized on the C-H bond.Original Russian Text Copyright © 2004 by O. V. Sizova, E. P. Sokolova, V. I. Baranovskii, D. A. Rozmanov, and O. A. Tomashenko__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 807–815, September–October, 2004.     

X-Ray Study of the Electronic Structure of Copper(II) Acetylacetonate

The Cu(acac)₂ complex was investigated by X-ray emission and XANES spectroscopy using synchrotron radiation. Structural data for the complex were obtained in chloroform solution and C₂F matrix. The experimental spectra and their fitting on a single scale of binding energies point to possible relaxation effects. As shown by model quantum-chemical calculations, the structure and energy position of the LUMOs constructed from the vacant metal 4p, 5p AOs strongly depends on the nature of the nearest environment.Original Russian Text Copyright © 2004 by L. N. Mazalov, S. V. Trubina, E. S. Fomin, I. M. Oglezneva, G. K. Parygina, N. V. Bausk, and I. K. Igumenov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 844–851, September–October, 2004.     

QSPR Modeling of the Reactivity Parameters of Monomers in Radical Copolymerizations

For a series of monomers, QSPR test analysis is performed by optimizing the correlation weights of the local invariants of molecular graphs representing monomer structures in order to construct models of the reactivity parameters of monomers Q and e. This approach may be used as a tool in reactivity predictions for monomers for which no experimental data on Q and e are available.Original Russian Text Copyright © 2004 by A. A. Toropov, V. O. Kudyshkin, N. L. Voropaeva, I. N. Ruban, and S. Sh. Rashidova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 994–998, November–December, 2004.     

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.     

Some structural peculiarities of CH3COOH-H2O binary mixtures according to proton spin-spin relaxation data

The proton spin-spin relaxation method was used to study the acetic acid-water binary system. The structure of the binary mixture is stabilized over the whole range of concentrations of acetic acid. For heterosolvates, the simplest composition has been determined.Original Russian Text Copyright © 2004 by V. Yu. Buzko, I. V. Sukhno, V. T. Panyushkin, and T. E. DzhioevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 751–754, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and crystal structures of anhydrous lithium and ammonium hypophosphites

Conditions of synthesis (temperature, precursors) have been selected to grow crystals of anhydrous lithium and ammonium hypophosphites. The crystal structure of LiH₂PO₂ has been determined. Cell parameters and atomic positions in (NH₄)H₂PO₂ at room temperature and at 100 K have been refined. By their oxygen atoms the hypophosphite anions serve to bridge the four cations. Each oxygen atom is bonded to two cations, creating puckered layers parallel to the (001) planes. The structures show much similarity in the general arrangement, but differ in the type of the tetrahedral cation-anion bonds. In LiH₂PO₂, the Li-O bond is ionic (1.933(4) Å); in (NH₄)H₂PO₂, N-H...O is a hydrogen bond (2.846(1) Å).Original Russian Text Copyright © 2004 by M. I. Naumova, N. V. Kuratieva, D. Yu. Naumov, and N. V. PodberezskayaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 491–496, May–June 2004.     

Electron Diffraction Determination of Equilibrium Structure for Rigid Molecules. Equilibrium Configuration of 1,2-Thiaarsol According to Gas-Phase Electron Diffraction and Quantum-Chemical Data

For rigid polyatomic molecules, a procedure is described for determining their equilibrium geometrical structures by processing gas-phase electron diffraction, spectroscopy, and quantum-chemical data. The efficiency of the procedure is demonstrated by reference to the 1,2-thiaarsol molecule. For this molecule, quantum-chemical calculations of different degrees of complexity have been carried out, and harmonic and anharmonic force fields have been constructed. The force constants were employed for determining the equilibrium geometry from experimental data. Analysis of the results of this study suggests that the calculated vibrational corrections to the internuclear distances are almost independent of the level of the quantum-chemical calculations.Original Russian Text Copyright © 2004 by Yu. I. Tarasov, I. V. Kochikov, D. M. Kovtun, N. Vogt, B. K. Novosadov, and A. S. Saakyan__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 822–829. September–October, 2004.     

Theoretical Analysis and Experimental Study of the Spatial Structure and Isomerism of Acetone Azine and Its Cyclization to 3,5,5-Trimethyl-4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrazole

An ab initio (RHF/6-31G*and MP2/6-31G*) study has been undertaken to investigate the spatial structure and relative stability of the acyclic isomers of acetone azine (acetone N-(1-methylethylidene) hydrazone (CH₃)₂C=N-N=C(CH₃)₂), differing in the position of multiple bonds, and of the cyclic isomer 3,5,5-trimethyl-4,5-dihydro-1H-pyrazole. In the series of structures under study, the latter possesses the greatest thermodynamic stability so that formation of acyclic isomers such as 1-isopropenyl-2-isopropyldiazene, acetone N-isopropenylhydrazone, and 1,2-diisopropenylhydrazine from acetone azine is thermodynamically unfavorable. For each structure, stable conformations have been found, and the internal rotation barriers of molecules relative to the N-N, C-N, and C-C single bonds have been estimated. The noncoplanar goshconformer of acetone azine was found to possess the greatest thermodynamic stability. The acetone azine molecule is considered in comparison with model hydrazine, butadiene, and vinylamine molecules. Acetone azine is conformationally preferable not only because of steric factors, but also due to the interaction of the lone electron pair (LEP) of nitrogen atoms with adjacent N=C multiple bonds.Original Russian Text Copyright © 2004 by V. B. Kobychev, N. M. Vitkovskaya, N. V. Pavlova, E. Yu. Schmidt, and B. A. Trofimov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 792–799, September–October, 2004.     

Structural Characteristics of Hydrated Complexes of Aminoacids in Aqueous Solutions

Aqueous solutions of nine α-aminoacids were studied in a diluted range of concentrations (from 0. 01 m to 0.1 m) at 5°C, 15°C, 25°C, 35°C, and 45°C based on the model that uses molar adiabatic compressibility (β _s V _m ) as a measure of hydration of the solute. For the resulting hydrated complexes of aminoacids, structural characteristics have been determined. At increased concentrations of the acid, variation of its hydration number is the chief factor affecting the molar compressibility of the hydrated complex.Original Russian Text Copyright © 2004 by V. N. Afanasiev, E. Yu. Tyunina, and V. V. Ryabova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 883–888, September–October, 2004.     

QSPR modeling of vitrification temperatures for polyarylene oxides

Prediction of the vitrification temperatures of polyarylene oxides based on optimization of the local invariant correlation weights of molecular graphs for the test sample is statistically characterized by n = 18, r = 0.9288, s = 12.8°C, F = 100.Original Russian Text Copyright © 2004 by A. A. Toropov, I. N. Nurgaliev, O. I. Balakhonenko, N. L. Voropaeva, I. N. Ruban, and S. Sh. RashidovaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 741–747, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Theoretical study of the conformations of triosmium clusters with a chiral carane ligand

A theoretical study has been performed to investigate the conformations of triosmium clusters with a chiral carane ligand . The potential curves of internal rotation have been determined for organic ligands rotating around the S-C bond in the cluster complexes. The structures of possible conformers are analyzed along with reasons for their stability. The rotation barrier relative to the S-C bond is 439.8 kJ/mole, which hinders free rotation of ligands.Original Russian Text Copyright © 2004 by V. A. Potemkin V. A. Maksakov, and V. P. KirinTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 430–434, May–June, 2004.     

Crystal structure of the synthetic analog of grechishchevite and Hg-X (X = S,Se, Te) bond topology in mercury chalcogen halides

This paper analyzes the structural data available for the synthetic analog of the mineral grechishchevite Hg₃S₂Br_1.00Cl_0.50I_0.50. The crystal structure of the synthetic mineral is refined. For chalcogen halides Hg₃X₂Hal₂ (X = S, Se, Te; Hal = Cl, Br, I), the paper presents an inventory of infinite and isolated ribbons, layers, and frameworks of covalently bonded Hg-X radicals growing into the pseudocubic matrix of halogen atoms.Original Russian Text Copyright © 2004 by N. V. Pervukhina, S. V. Borisov, S. A. Magarill, D. Yu. Naumov, V. I. Vasiliev, and B. G. NenashevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 462–470, May–June, 2004.