Redox reactions of GeII and SnII dihalides with triethylsilane and triethylgermane

Dihalogermylenes, dihalostannylenes, and their complexes (EI₂, ECl₂·dioxane, and (CO)₅W=ECl₂·THF, where E = Ge or Sn), unlike organylgermylenes, are not inserted at the Si—H (Ge—H) bond of triethylsilane (triethylgermane). The reactions of SnI₂, ECl₂·dioxane, and (CO)₅W=ECl₂·THF (E = Ge or Sn) with Et3E"H (E" = Si or Ge) occur as redox processes. Depending on the nature of the reagents, the reactions afford products of oxidative coupling (Et₃SiSiEt₃) and/or haloiodination (Et₃SiX and Et₃GeX) of triethylsilane (triethylgermane). The proposed mechanism of these reactions involves the electron transfer to form radical-ion pairs.     

X-ray diffraction study of acid anilinium dodecatungstenphosphate

Acid anilinium dodecatungstenphosphate of composition (C₆H₅NH₃)₂H[PW₁₂O₄₀] 2H₂O is synthesized and characterized by X-ray diffraction analysis, IR spectroscopy, and thermogravimetry. The crystals are monoclinic: space group P2₁/m, a = 9.940(2) , b = 15.412(3) , c = 16.201(3) , = 100.42(3)°, Z = 2, _calcd = 4.221 g/cm³. The structure contains heteropolyanions [PW₁₂O₄₀]^3–, cations [C₆H₅NH₃]⁺ and H⁺, and molecules of water of crystallization. The heteropolyanions and anilinium cations in crystal are linked by the electrostatic interaction and hydrogen bonds.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 273–279.Original Russian Text Copyright © 2005 by Kaziev, Dutov, Quinones, Koroteev, Belskii, Stash, Kuznetsova.     

Kinetics and Thermodynamics of Hydrogen Atom Exchange Reactions in Sterically Hindered Hydroxylamine-Nitroxyl Radical Systems

Rate constants and activation energies were determined for the forward and reverse hydrogen exchange reactions in systems involving a sterically hindered hydroxylamine and a nitroxyl radical of dihydroquinoline, tetrahydroquinoline, diphenylamine, imidazoline, pyrrolidine, or piperidine. The equilibrium constants and heats of these reactions were determined, and the dissociation energies of the NO-H bonds in the hydroxylamines were estimated.     

The exchange reaction of hydrogen atoms in the system sterically hindered hydroxylamine-nitroxyl radical

The rate constants of the direct and reverse exchange reactions of the hydrogen atom in the system sterically-hindered nitroxyl radical-hydroxylamine of the quinoline, imidazoline, pyrrolidine, and piperidine series as well as diarylhydroxylamine were determined. A scale of the reductive abilities of the hydrolamines was established. A low value of the isotope effect is typical of the reactions of hydrogen exchange in the systems hydroxylamine-nitroxyl radical. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1324–1328, July, 1998.     

Effect of the chemical structure of nitroxyl radicals on their reactivity in the reaction with hydrazobenzene and tetranitromethane

The reaction rate constants of reduction of stable radicals of different classes by hydrazobenzene in hexane at 20C, in the range of 0.4–5·10³ M^–1sec^–1, were determined; a single scale of the oxidative properties of stable nitroxyl radicals was constructed. The rate constants of oxidation of a series of nitroxyl radicals by tetranitromethane in aqueous medium at 20C, in the range of 0.06–10 M^–1·sec^–1, were determined. It was shown that the oxidative properties of the nitroxyl group decrease slightly with an increase in its reducing properties for nitroxyl radicals of the piperidine and imidazoline series in reactions with ascorbic acid and tetra-nitromethane in aqueous medium, respectively.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2575–2582, November, 1990.     

Phosphorylation of alkyl tert-butyl ethers

Conclusions Monobutyl phosphite, tributyl phosphate, and triamyl phosphate were synthesized by the reaction of phosphorylating agents with the appropriate alkyl tert-butyl ethers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1867–1868, August, 1972.     

Synthesis of bis(glycosylamino)alkanes and bis(glycosylamino)arenes

The condensation of D-mannose and D-galactose with aliphatic and aromatic diamines afforded a series of bis(glycosylamino)alkanes and-arenes. A possible mechanism was proposed for the formation of 1,2-bis(β-D-glycosylamino)benzenes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2793–2801, December, 2005.     

Mutual influence of hydrogen and vacancies in α-zirconium on the energy of their interaction with metal

We presents a first-principles investigation on the interaction energy of hydrogen and vacancies with α-zirconium. It is established that the presence of vacancies in zirconium increases the hydrogen–metal binding energy; the presence of hydrogen in the zirconium lattice reduces the vacancy formation energy. It is shown that hydrogen and vacancies in zirconium form complexes that considerably distort the metal lattice. The increase in the covalency degree of the metal–metal and hydrogen–metal bounds is observed in the vicinity of these complexes.     

Generation of the second optical harmonic in porous-silicon-based structures with a photonic band gap

Efficient generation of the second optical harmonic is observed experimentally in a multilayer periodic structure based on porous silicon. The second-harmonic signal is much stronger than the signal from a uniform porous silicon layer or from the single-crystal silicon substrate. The orientational dependence of the second-harmonic signal is isotropic. The second-harmonic intensity as a function of the reflection angle reaches a maximum in the direction corresponding to the minimum phase detuning in a multilayer periodic structure. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 4, 274–279 (25 February 1999) Deceased.     

Effect of High-Lying Resonances on Cross Sections for Solar-Neutrino Capture by $${}^{\mathbf{127}}$$ I Nuclei

Physics of Atomic Nuclei - The resonance structure of the charge-exchange strength function $$S(E)$$ and its effect on the cross sections for solar-neutrino capture by $${}^{127}$$ I nuclei are...