A new technology of wood cavitation

Wood residue crumbling with a rotary-pulse device is considered. Structural analysis of the resulting materials is carried out.     

Mononuclear Transition Metal Cymantrenecarboxylates as Precursors for Spinel-Type Manganites

Novel mononuclear cymantrenecarboxylate complexes of transition metals, [Co(H₂O)₆](CymCO₂)₂·4H₂O (Cym = (η⁵-C₅H₄)Mn(CO)₃) (1), [Ni(H₂O)₆](CymCO₂)₂·4H₂O (2), [Zn(H₂O)₆](CymCO₂)₂·4H₂O (3), [Co(CymCO₂)₂(imz)₂] (imz = imidazole, 4), [Co(CymCO₂)₂(bpy)₂]·2PhMe (bpy = 2,2′-bipyridyl, 5), [Ni(CymCO₂)(bpy)₂(H₂O)][CymCO₂]·0.5MePh·2H₂O (6), [Cu(CymCO₂)₂(imz)₂] (7), and [Cu(CymCO₂)₂(bpy)(H₂O)] (8), were obtained and characterized by single-crystal X-ray analysis. Complexes 1–3 are isostructural. Magnetism of the Co complexes 1, 4, and 5 was studied; it was shown that they exhibit the properties of field-induced single-molecule magnets with magnetization reversal barriers (ΔE/k_B) of 44, 13, and 10 K, respectively. Thermal decomposition of complexes 1–8 was studied by means of DSC and TGA methods. The final products of thermolysis of 1–6 in air, according to powder XRD data, are the pure spinel phases MMn₂O₄; for the cases of copper complexes, the mixtures of CuMn₂O₄ and CuO were found in the products.     

Self-and cross-phase modulation accompanying third-harmonic generation in a hollow waveguide

The influence of self-and cross-phase modulation on third-harmonic generation in a hollow waveguide is investigated. Analytic solutions of the coupled equations for the slowly varying amplitudes of the pump pulse and the third harmonic in a gas-filled hollow waveguide are obtained with consideration of self-and cross-phase modulation and first-order dispersion effects. The possibility of controlling the nonlinear phase trajectory of the third harmonic by cross-phase modulation is demonstrated. Zh. éksp. Teor. Fiz. 115, 1561–1579 (May 1999)     

Phosphorylation of 3-hydroxy- and 5,7-dihydroxyflavones with hexaethylphosphorous triamide

The reactions of 3-hydroxy- and 5,7-dihydroxyflavones with hexaethylphosphorous triamide proceed according to a classical scheme, but the reaction of 5,7-dihydroxyflavone occurs regioselectively. Dismutation of phosphites, which has been studied earlier only for the simplest aryl systems, is extended to flavonoids.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2698–2702, December, 2004.     

Direct STM observation of electronic structure modification of naphthacenequinone molecules due to photoisomerization

Light-induced conformational transformations of the naphthacenequinone (NQ) molecules are observed by scanning tunneling microscopy (STM). NQ molecules packed in a Langmuir-Blodgett (LB) film are shown to form stable ordered structures on a surface of highly oriented pyrolytic graphite (HOPG). The local density of electronic states is found to exhibit the distinct peak which is characteristic of two-dimensional conductivity. An additional subband of empty electronic states is found for NQ molecules in form A but not in form B. The constant-height STM images of individual molecules in form A demonstrate an additional structure that is indicative of a conformational transition of the NQ molecules. This transition involves the transfer of the phenoxy group from one oxygen to another. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 6, 486–490 (25 September 1998)     

Synthesis and study of acid ammonium metaphenyleneamine dodecatungstenphosphate (C6H4(NH2)(NH3))2H[PW12O40] · 8H2O

Acid ammonium metaphenyleneamine dodecatungstenphosphate of the composition (C₆H₄(NH₂)(NH₃))₂H[PW₁₂O₄₀] · 8H₂O is synthesized and studied by mass spectrometry, X-ray diffraction, IR spectroscopy, and thermogravimetry. The crystals are rhombic, space group Pnma, a = 18.421(2), b = 19.569(3), c = 13.443(3) ?, Z = 4, ρ(calc) = 4.431 g/cm³, V = 4845.9(2) ?³. Original Russian Text ? S. Holguin Quinones, G.Z. Kaziev, A. de Ita, A.M. Koroteev, V.E. Zavodnik, O.A. Kutanova, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 9, pp. 660–664.     

Kinetics,mechanism, and reactivity of an activated carbon-carbon double bond in nitroxyl radicals and their diamagnetic analog in interaction with some secondary amines and polyethyleneimine

Routes for the reaction of a conjugated methylene group of nitroxyl radicals (NR) with secondary amines were suggested and analyzed. Kinetic parameters of the limiting step of this reaction for the NR-amine and diamagnetic analog of NR-amine systems were estimated. The effect of the medium on these reactions was examined. The specific behavior of polyethyleneimine in the reaction with activated methylene groups of 2,2,6,6-tetra methyl-3, 5-dimethylene-4-oxopiperidine-i-oxyl was demonstrated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 842–849, April, 1996.     

Peculiarities of thermal decomposition of inorganic and organometallic compounds of GeIV and GeII. Thermolysis of (acac)2GeX2 (X = Cl,N3) and (CO)5MGeCl2(thf) (M = Cr,Mo, W)

Thermal decomposition of the complexes (acac)₂Ge(N₃)₂ (1), (acac)₂GeCl₂ (2), and (CO)₅M=GeCl₂(THF) (M = Cr (3), Mo (4), W (5)) was studied by differential scanning calorimetry and thermogravimetry. The phase compositions of the products of thermolysis of compounds 1—3 and 5 were determined by X-ray phase analysis. Possible schemes of thermal decomposition of these compounds were proposed. The heat capacities of complexes 3—5 were studied in the temperature range 113—313 K. The structures of complexes 1 and 5 were established by X-ray diffraction analysis.     

Preparative Synthesis and Structure of 2,2-Bis(hydroxymethyl)propyl and 2,2-Bis(hydroxy-methyl)butyl Phosphites

Conditions were found for selective hydrolysis of bicyclic phosphites derived from 2,2-bis-(hydroxymethyl)-1-propanol and 2,2-bis(hydroxymethyl)-1-butanol to the corresponding dihydrogen phosphites. The latter were isolated as potassium, sodium, and ammonium salts and were characterized by the ¹H, ¹³C, and ³¹P NMR spectra. The structure of the ammonium salt was proved by X-ray analysis.     

Reactions of hydrazobenzene and tetranitromethane with nitroxyl radicals

The values of isotropic HFS constantsa _N were obtained for nitroxyl radicals (NR) of the piperidine series in hexane and water. The interrelation between rate constants for NR reduction and oxidation reactions, isotropic HFS constantsa _N, inductive constants of the piperidine substituents, and electrochemical characteristics of NR were found. The dependence of the rate constants for the reduction of NR by hydrazobenzene (HB) and its oxidation by tetranitromethane (TNM) upon the Hammett type inductive constants _EPR, obtained using HFS constantsa _N as the basis, was analyzed. The solvent effect on the reduction and oxidation reaction rate constants, the kinetic isotopic effect of the reduction reaction for a number of NR-HB systems, and alternative reaction mechanisms are considered.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1074–1079, June, 1993.