Synthesis,structure, and properties of benzosulfinyl-11-crown-4

Conclusions The possibility of cooperative complex formation of three electron donating oxygen atoms with metal ions has been demonstrated in a novel macrocyclic compound, namely, benzosulfinyl-11-crown-4, which exhibits significant physiological activity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2576–2578, November, 1988.     

Molecular structure of dibenzoadamantylphosphonyl-17-crown-6 in the crystalline state and in solutions

Conclusions It has been shown that for dibenzoadamantylphosphonyl-17-crown-6 in the crystalline state and in solutions, the characteristic conformation has separate orientations of the unshared electron pairs of the oxygen atom, owing to the presence of the bulky adamantyl grouping.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2028–2036, September, 1984.     

Electronic structure and models of monooxygenase inductor receptor from a number of polychlorinated polycyclic compounds. 5. MNDO calculations of halogen derivatives of azoxybenzenes

The MNDO method has been used to calculate the electronic and geometric structure of 3,3,4,4-tetraehloroazoxybenzene (TCAOB), 3,3,4,4-tetrachloro-6-hydroxyazobenzene (TCHAB), and 2,3,7,8-tetrachlorodibenzofuran (TCDF). The TCAOB exists in the gas phase in the form of two configurations, one nonplanar and one nearly planar. The latter is approximately 4 kcal/mole less stable than the first. The oxidation of 3,3,4,4-tetrachloroazobenzene (TCAB) to TCAOB is endothermic only in the case of the acton of hydrogen peroxide, not molecular oxygen. The isomerization of TCAOB to TCHAB proceeds with a gain in energy (–62 kcal/mole); however, the reaction from the ground state of the TCAOB molecule is symmetry-forbidden and is possible only from an excited state of the TCAOB. The process of oxidation of TCAOB and TCHAB by molecular oxygen to form TCDF or 2,3,7,8-tetrachlorobenzo-p-dioxin is energy-favorable; this is important in judging the biological action of TCAOB.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 101–105, January, 1991.     

Temperature-Dependent Structure-Energy Changes in Crystals of Compounds with Poly(hydroxymethyl) Grouping

Crystals of tris(hydroxymethyl)nitromethane (1) and tris(hydroxymethyl)aminomethane (2) were prepared and grown at room temperature. X-ray analysis was used to study the structure of crystals 1 and 2 at room temperature; the X-ray diffraction method was applied to investigate polycrystalline samples during a temperature rise up to the phase transition into the plastic phase. Phase transitions in separate crystals 1 and 2 were observed in a hot stage under an optical microscope. Calorimetric study of the crystal temperature behavior and the phase transition features including melting were carried out. By IR spectroscopy the temperature relations of the bonds of symmetric N-O stretching vibrations of nitro groups and stretching vibrations of OH groups redistribution in crystals of 1 were investigated. In crystals of 2 the behavior of stretching vibration bands of O-H groups was studied at room temperature. In the temperature interval including phase transition, data on structure-dynamic rearrangements in the crystal lattice of compounds 1 and 2 were obtained by the NMR pulse method in the solid phase using relaxational free induction decay of protons. The proton conductivity was found and its temperature parameters were determined for both compounds in the plastic state.     

35Cl and79Br NQR spectra of halofluorosulfates

Conclusions NQR spectroscopy was used to find the localization of formal positive charge on the chlorine and bromine atoms in ClOSO₂F and BrOSO₂F.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 244–245, January, 1986.     

Growth of unusual carbon nanofilaments in methane pyrolysis

Two types of carbon nanofilaments (nanotubes) differing markedly in morphology and growth rate grow on substrate plates containing a supported catalyst in a methane atmosphere at ～1050°C. According to provisional estimates, nanofilaments of one of these types grow at a rate of 5–10 μm/s, which is 50–100 times as high as the growth rate observed for ordinary catalytic filaments (tubes). These filaments are as long as several millimeters, being 50 to 100 nm in diameter. A preliminary examination of their structure has demonstrated that there is no catalyst particle at the filament end and that the filament is likely a carbon-rich polymer. A possible mechanism of the growth of these carbon filaments is discussed.     

Multiplicity of eigenvalues in certain boundary value problems for the Helmholtz equation

Boundary value problems for two-layer cylindrical waveguides (namely, for a circular two-layer closed waveguide and a dielectric waveguide in an unbounded medium) are considered. It is shown that the same eigenvalues determining the wave numbers of waves in the waveguides can correspond to different solutions of the boundary value problem.     

Electron structure and reactivity of organofluorine compounds. 4. AMI calculations of anion radicals of primary,secondary, and tertiary perfluoroalkyl chlorides,bromides, and iodides

Calculations were carried out using the semiempirical quantum chemical AMI method for anion radicals (AR) of the perfluoroalkyl halides (R_FX): CF₃X, CF₃CF₂X, (CF₃)₂-CFX, and (CF₃)₃CX for X=Cl, Br, and I. All the AR's studied are thermally stable. The electron affinity of the perfluoroalkyl halides, and consequently, the thermal stability of their AR's increases in the series from F-methyl to F-tertbutyl halides and from the chlorides to bromides and iodides. During formation of an AR the spin density is preferentially localized on the * orbital of the C–X bond which leads to an increase in the distance between these atoms. Dissociation of the AR of tert-perfluorobutyl iodide to a perfluorocarbanion and an I atom is thermodynamically more favorable than dissociation with formation of a perfluoroalkyl radical and I^–.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1064–1068, May, 1990.     

Electron structure and reactivity of organofluorine compounds. 3. Mndo and ami calculations of the ground state of perfluoroalkyl chlorides,bromides, and iodides

The semiempirical quantum chemical MNDO and AMI methods were used to determine the equilibrium geometries and electron properties of molecules of perfluoroalkyl halides (R_FX): CF₃X, CF₃CF₂X, (CF₃)₂CFX, (CF₃)₃CX for X=Cl, Br, and I. It was determined that the effective charge on the Cl atom in R_FCl is negative, positive on the I atom in R_FI, and depends on R_F for the Br atom in R_FBr. The CF₃ group can act as either an electron acceptor or donor in various perfluoroalkyl halides. The strongest C–I bond in the perfluoroalkyl halides occurs with a tertiary RF group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1059–1063, May, 1990.