Connection between the electronic structure of tin in its compounds and the isomer shifts in the Mössbauer spectra

A formula is obtained which relates the isomer shifts in the Mössbauer spectra to the electronic structure of tin in its compounds. It is shown that these formulas describe the isomer shifts of various kinds of chemical compounds: tetravalent tin with -bonding (tin tetrahalides), tetravalent tin with no -bonding (compounds in which the tin is bound to alkyl, aryl, or metal carbonyl radicals), divalent tin, etc. The formulas are used to analyze the electronic structures of tin in compounds of these classes. It is shown that in tetravalent tin compounds with -bonding the isomer shift in the negative direction (with respect to -Sn) is due to the decreased number of 5s-valence electrons, and in the absence of -bonding, by an increase in the number of 5s-valence electrons.     

Synthesis and Properties of First Bis(fluoreno)crownophanes

Alkylation of 2,7-dihydroxy-9H-fluoren-9-one with 2-(2-chloroethoxy)ethanol, 2-[2-(2-chloroethoxy)-ethoxy]ethanol, and 2-{2-[2-(2-chloroethoxy)ethoxy]ethoxy}ethanol in dimethylformamide in the presence of potassium carbonate gave 78–80% of the corresponding diols which were treated with p-toluenesulfonyl chloride in a dioxanechloroform mixture in the presence of triethylamine at 0– 5°C (30 h). The resulting bis(p-toluene-sulfonates) were brought into condensation with 2,7-dihydroxy-9H-fluoren-9-one in a very dilute solution in dimethylformamide containing anhydrous potassium carbonate at 80–85°C. Appropriate treatment of the reaction mixture, followed by chromatographic purification afforded 53–27% of the first representatives of a new class of cyclophanes, bis(oxofluoreno)crownophanes. Raising the temperature to 95–105°C resulted in an appreciable decrease of the product yield. The yield of the target products did not increase on replacement of potassium carbonate by cesium carbonate.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 144–149.Original Russian Text Copyright © 2005 by Lyapunov, Kirichenko, Kulygina, Luk’yanenko.     

Synthesis of Sybstituted Isoxazoles and Pyrazoles Based on 1-Aryl-3,4,4-trichloro-3-buten-1-ones

3-Aryl-5-methylenehydroxyiminoisoxazoles were synthesized by reaction of 1-aryl-3,4,4-trichloro-3-buten-1-ones with hydroxylamine. Reactions of ketones with hydrazine provided pyrazole structures; therewith two pyrazole molecules underwent coupling affording 3-arylpyrazole-5-carbaldehyde azines.     

The Effect of Surface Forces on the Thermal Slip of a Simple Gas

The flow of a simple gas along a plane surface under the action of tangential temperature gradient is considered. The velocity of thermal slip is calculated by the variational method with account of the effect of surface forces. It is shown that, in some situations, surface forces can substantially affect the value of the thermal slip coefficient.     

Me2ESiMe3 (E = As,N, P) Compounds—Efficient Reagents for Replacement of the Fluorine Atom by Me2E Group in the Complex [(η6-1-F-3,5-Me2C6H3)(η5-C5EtMe4)Rh](CF3SO3)2 >

Russian Journal of Organic Chemistry -     

Kinetics and Mechanism of Monomolecular Heterolysis of Commercial Organohalogen Compounds: XXXVII.1 Effect of Nucleofuge and Solvent of the Relative Rates of Heterolysis of 1-Halo-1-methylcyclopentanes and 1-Halo-1-methylcyclohexanes. Correlation Analysis of Solvation Effects

The effect of solvent ionizing ability on heterolysis rate enhances in the series 1-chloro-1-methylcyclohexane < 1-bromo-1-methylcyclohexane 1-chloro-1-methylcyclopentane < 1-bromo-1-methyl- cyclopentane. The lower sensitivity of cyclohexyl substrates compared with cyclopentyl is determined by conformational effects. Bromides are more sensitive to solvent effects than chlorides because of the stronger polarizability of the C-Br bond.     

Chlorine derivatives of octaorganylsilasesquioxanes

The chlorination of saturated and unsaturated octaorganylsilasesquioxanes proceeds through two pathways, leading to the formation of volatile and nonvolatile products, whose ratio depends on the reaction conditions. The volatile products of the chlorination of R-T₈ (R=C₂H₅ and CH=CH₂) are compounds with the general formula Cl_nR_8–n[SiO_1.5]₈, (n=1–7), obtained independently of the nature of the organic substituent and chlorinating agent. The nonvolatile chlorination products are silasesquioxanes, containing chlorine and chloroalkyl substituents on the atoms of the silicon-oxgyen core. Analysis of the vibrational spectral data indicated that the most significant changes in the molecular vibrational system are made by the halogenation of the silicon-oxygen core Si₈O₁₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 446–450, February, 1990.     

Photoreduction of benzophenone by dimethylaminoethyl methyacrylate in solutions

The photoreduction of benzophenone by dimethylaminoethyl methacrylate was investigated under the conditions of stationary and pulsed irradiation. With stationary irradiation of this system in benzene an intermediate photoproduct is formed, and its destruction is described by a kinetic equation of second order. By irradiation under pulsed conditions it is possible to detect the formation of the ketyl radicals of benzophenone, the yield and destruction of which depend substantially on the nature of the medium. The relationship between the destruction constant and the concentration of the aminomethacrylate and butyl methacrylate was examined and explained; the constant increases with decrease in the aminomethacrylate concentration and with increase in the butyl methacrylate concentration. The mechanism of the photoreduction of aromatic carbonyl compounds by aminomethacrylates is described.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 1, 56–62, January–February, 1990.     

Neutron activation for precise nuclear data

Techniques for extracting neutron flux parameters pertaining to the irradiation positions and nuclear data pertaining to the isotopes concemed from measured reaction rates have been developed. An adjustment procedure based on the generalized least squares method with incorporates the, evaluated literature nuclear data, estimates of flux parameters and the experimentally measured reaction rates using high resolution -ray spectrometry is applied. More precise values of the nuclear data, i.e., thermal neutron cross sections, resonance integrals and -ray emission probabilities are thus generated. The irradiation of a multi-element standard (MES) containing 24 elements is carried out in six diffieret positions in two diverse types of reactor in the UK and Russia. It is shown that the improvement in nuclear data is revelaed in moire than 90% of the cases.     

Alkaloids ofPetilium raddeana II. Structures of petisine and petisinine

The alkaloids imperialine, imperialone, peumisine, petiline, petilidine, and the new bases petisine (I) and petisinine (III) have been isolated from bulbs ofPetilium raddeana (Regl.) Vved. On the basis of spectral characteristics and passages to a known compound, the structure of 3-hydroxy-²²(N)-22,26-iminocholestane-6,23-dione has been established for (I) and petisine 3-glucopyranoside for (III).Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 616–619, September–October, 1981.