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Showing papers in "Russian Chemical Bulletin in 2011"


Journal ArticleDOI
TL;DR: In this paper, magnetron sputtering was successfully used to obtain nanosized metal films and metal nanoparticles, which can be useful for development of novel methods in organic chemistry, and morphology of the nanosised (5-100 nm) objects obtained was examined by SEM.
Abstract: Magnetron sputtering was successfully used to obtain nanosized metal films and metal nanoparticles, which can be useful for development of novel methods in organic chemistry. The morphology of the nanosized (5–100 nm) objects obtained was examined by SEM. The pattern of dependence of the morphology and size of the nanosized objects on the nature of the support surface, the metal, and the sputtering conditions is described.

137 citations


Journal ArticleDOI
TL;DR: In this article, a review summarizes the results of studies aimed at developing the fundamentals for the design of a new class of nitric oxide donors, viz., iron nitrosyl complexes with functionalized sulfur-containing ligands.
Abstract: The review summarizes the results of studies aimed at developing the fundamentals for the design of a new class of nitric oxide donors, viz., iron nitrosyl complexes with functionalized sulfur-containing ligands, which are structural analogs of the active sites of non-heme nitrosyl iron-sulfur proteins. The structures, reactivities, and pharmacological activity in vitro and in vivo of these complexes are considered.

44 citations


Journal ArticleDOI
TL;DR: In this article, a review of methods of synthesis of chalcogen-nitrogen π-heterocyclic radical anion salts derived from 1,2,5-chalcogenadiazole is presented.
Abstract: The review concerns methods of synthesis, as well as the molecular, electronic, and crystal structures and the magnetic properties of a novel class of paramagnetic compounds, namely, chalcogen-nitrogen π-heterocyclic radical anion salts derived from 1,2,5-chalcogenadiazole.

32 citations


Journal ArticleDOI
TL;DR: An efficient inhibitor of the CMV infection from the class of amino acid derivatives of fullerene with antioxidant activity was obtained.
Abstract: The antioxidant properties of water-soluble amino acid derivatives of fullerene C60 (ADF) were studied It was shown by the change in the concentration of malonic dialdehyde in rat brain mitochondria that the ADF are antioxidants They were shown by the change in the luminol glow to possess antiradical activity, which is determined by the acceptor properties of the fullerene spheroid and is independent of the structure of the attached addends Stereoselectivity of the antioxidant properties of the enantiomers of amino acid derivatives of fullerene C60 was found The L-isomers of ADF inhibit lipid peroxidation, whereas the D-isomers do not inhibit A reliable correlation between the development of cytomegalovirus (CMV) infection and the process of lipid peroxidation in the cell culture was established An efficient inhibitor of the CMV infection from the class of amino acid derivatives of fullerene with antioxidant activity was obtained

31 citations


Journal ArticleDOI
TL;DR: In this paper, a new procedure for the preparation of biocompatible gold nanoparticles using bioflavonoids: rutin, quercetin, and luteolin as reducing agents and stabilizers was proposed.
Abstract: A new procedure for the preparation of biocompatible gold nanoparticles using bioflavonoids: rutin, quercetin, and luteolin as reducing agents and stabilizers was proposed. On varying the bioflavonoid concentration, nanoparticles of different size are formed. By the combined use of spectroscopy and atomic force microscopy, the nanoparticle size was estimated (40–50 nm). Uniform and highly dispersed gold nanoparticles were obtained at Au: rutin ratios of 1: 1, 2: 1, and 4: 1 and Au: quercetin ratios of 2: 1 and 4: 1. The nanoparticle yield remains almost constant as the Au: rutin ratio varies over a broad range from 1: 1 to 12: 1. It was suggested that complete reduction of AuIII to Au0 with a large excess of Au is accompanied by extensive oxidation of bioflavonoid involving an intermediate oxidant formed in the system due to the high oxidative capacity of AuIII. For elucidating the catalytic role of bioflavonoids in the formation of gold nanoparticles, quantum chemical modeling of the process was performed.

28 citations


Journal ArticleDOI
TL;DR: The results of the present study indicate that chondroitin sulfates deserve more detailed investigation as potential anti-inflammatory agents.
Abstract: Chondroitin sulfates isolated from cartilage of five marine fish species: Atlantic salmon (Salmo salar), Greenland shark (Somniosus microcephalus), blackmouth catshark (Galeus melastomus), birdbeak dogfish (Deania calcea), and Arctic skate (Amblyraja hyperborea), were characterized in detail by 1H and 13C NMR spectroscopy. The complete signal assignments for carbohydrates were made and the relative contents of the key structural units were estimated by 2D homonuclear and heteronuclear NMR spectroscopy (COSY, TOCSY, NOESY, HSQC, and HMBC). The average length of the polysaccharide chain was evaluated from the integrated intensity ratio of the terminal and internal monosaccharide residues. The anti-inflammatory and anticoagulant activities of the specimens were studied. Chondroitin sulfates from salmon and Arctic skate exhibit considerable anti-inflammatory activity. All specimens manifest weak anticoagulant activity. The results of the present study indicate that chondroitin sulfates deserve more detailed investigation as potential anti-inflammatory agents.

28 citations


Journal ArticleDOI
TL;DR: In this article, the crystal structure is composed of polymeric cationic [(H3O)2(phz)3] and anionic [Mn2(C6O4Cl2)3]-layer having honeycomb structure and stacked in such a way that open-ended through-going channels accommodating H2O and CH3COCH3 solvent molecules are formed.
Abstract: Crystalline compounds (H3O)2(phz)3M2(C6O4Cl2)3·(CH3COCH3) n ·(H2O) n (n = 0−2, M = Mn (1), Fe (3)) were obtained in an acetone-water-tetrahydrofuran medium by the reaction of metal sulfates with chloranilic acid and phenazine (phz). The molecular and crystal structure of 1 was studied by X-ray diffraction at 300, 200, and 150 K. The crystal structure is composed of polymeric cationic [(H3O)2(phz)3] n 2n+ and anionic [Mn2(C6O4Cl2)3] n 2n− layers having honeycomb structure and stacked in such a way that open-ended through-going channels accommodating H2O and CH3COCH3 solvent molecules are formed; the H3O+ cations in the crystal structure are disordered. Magnetic studies indicate antiferromagnetic coupling of Mn2+ ions through chloranilate ligands; transition to a magnetically ordered state occurs at T = 5 K. According to powder X-ray diffraction data, complex 3 is isostructural with compound 1 but differs crucially from 1 in the electronic structure. According to Fe57 Mossbauer spectroscopy, complex 3 exists in delocalized mixed-valence Fe2+/Fe3+ state and, as a consequence, shows ferromagnetic character of magnetic correlations and semiconductor type of electrical conductivity. These features were ascribed to the valence tautomerism Fe2+ + (C6O4Cl2)2− → Fe3+ + (C6O4Cl2)·3−, which was observed for the first time for iron in a honeycomb structure.

25 citations


Journal ArticleDOI
TL;DR: In this paper, a reaction of aminofurazanes with 2,2-dimethyl-5-nitro-1,3-dioxan-5 -yl-ONN-azoxy)-furazanes is described.
Abstract: A reaction of aminofurazanes with 2,2-dimethyl-5-nitro-5-nitroso-1,3-dioxane in the presence of dibromoisocyanurate furnished (2,2-dimethyl-5-nitro-1,3-dioxan-5-yl-ONN-azoxy)-furazanes. Their reactions with AcCl/MeOH and subsequent transformations led to the first members of substituted mononitroalkyl- and (polynitroalkyl-ONN-azoxy)furazanes, viz., 3-(nitromethyl-ONN-azoxy)-4-nitrofurazane, 3-(dinitromethyl-ONN-azoxy)-4-nitrofurazane, 3-(trinitromethyl-ONN-azoxy)-4-nitrofurazane, and some of their derivatives and analogs.

24 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the use of selenium dihalides for annulation of phenyl ethers containing unsaturated groups by combination of the addition to the unsaturated bond and electrophilic sub stitution in the ortho position of the benzene ring.
Abstract: We are performing systematic studies aimed at the ap plication of novel reagents, such as selenium dichloride and dibromide, in the chemistry of organoselenium com pounds.1—6 Although these reagents cannot be isolated in pure state and undergo disproportionation in solutions7, it has been shown1 that freshly prepared selenium dichloride and dibromide can be used as selective electrophilic re agents in the synthesis of organoselenium compounds. The reactions of selenium dichloride and dibromide with acet ylene,2 diphenylacetylene,3 divinyl sulfide,4 divinyl sul fone,5 divinyl selenide,6 propargyl alcohols,8 2,3 di methoxybuta 1,3 diene9 have been studied. In contrast to selenium tetrahalides, whose reactions with organic sub stances often afford mixtures of products10, the reactions of selenium dihalides proceed selectively to afford the tar get compounds in high yields.1—6,8,9 The use of selenium dihalides for annulation of phenyl ethers containing unsaturated groups by combination of the addition to the unsaturated bond and electrophilic sub stitution in the ortho position of the benzene ring is of the utmost interest. There are no data on annulation of phenyl propargyl ether with selenium halides. We studied the reaction of selenium dichloride with phenyl propargyl ether and found the conditions that al low selective preparation of previously unknown E 3 chloromethylidene 2,3 dihydro 1,4 benzoxaselenine (1). The highest yield of product 1 (80%) was obtained upon mixing reagents at low temperature (–60 °C) in chloro form followed by heating the reaction mixture to the boil ing temperature of the solvent. One can assume that the addition of selenium dichlo ride to the propargyl group occurs at low temperature and the second step, viz., electrophilic aromatic substitution, requires heating of the reaction mixture. The structure of product 1 was established by 1H, 13C (including JMOD), and 77Se NMR spectroscopy and con firmed by the data from mass spectrometry and elemental analysis. The value of spin spin coupling constant (100 Hz) between the selenium atom and the double bond carbon atom having no protons corresponds to the C—Se direct constant (JC—Se), which is evidence of the addition of the selenium atom to the central carbon atom of the propargyl group. The E configuration of product 1 was established using the NOESY spectra. The regio and stereospecificity of the process can be explained by the fact that the reaction proceeds via the intermediate selenirenium ion А, which is attacked by the chloride ion at the sterically unshielded terminal car bon atom. Thus, we showed for the first time the possibility of annulation of the selenium containing heterocycles to the benzene ring based on the reaction of selenium dichloride with unsaturated organyl phenyl ethers, where the addi tion of selenium halides to the unsaturated bond of orga nyl phenyl ethers and electrophilic aromatic substitution is combined.

24 citations


Journal ArticleDOI
TL;DR: The bistable cobalt complex containing two symmetrical 3,6-di-tert-butyl-o-benzoquinone and one 1,10-phenanthroline moieties as ligands (1) was synthesized as mentioned in this paper.
Abstract: The bistable cobalt complex containing two symmetrical 3,6-di-tert-butyl-o-benzoquinone and one 1,10-phenanthroline moieties as ligands (1) was synthesized. Complex 1 was isolated in the individual state and characterized by IR and ESR spectroscopy, X-ray diffraction, magnetochemical studies, and precision calorimetry. A change in temperature causes the reversible metal-ligand electron transfer and spin crossover (redox isomerism) in complex 1 in the crystalline state. The redox-isomeric transformation at ∼250 K is accompanied by the phase transition. The structural study at two temperatures confirmed the changes in the molecular and crystal structure associated with the redox-isomeric transformation.

24 citations


Journal ArticleDOI
TL;DR: In this paper, the conditions that allow one to synthesize both linear and cyclic methylphenylsiloxanes by using acetic acid excess were found. And the possibility to prepare linear polymethylphenylsoxanes with the molecular weight up to 34000 amu was shown.
Abstract: Polycondensation of methylphenyldialkoxysilane was studied under the conditions of an active medium, namely, an acetic acid excess, being simultaneously a reactant, catalyst, and solvent. This method was shown to be universal for the synthesis of a wide range of polymethylphenylsiloxanes of diverse structure. The conditions that allow one to synthesize both linear and cyclic methylphenylsiloxanes by this method were found. The possibility to prepare linear polymethylphenylsiloxanes with the molecular weight up to 34000 amu was shown.

Journal ArticleDOI
TL;DR: In this paper, a review summarizes the results of recent studies of aromatic polyazides and high-spin nitrenes carried out at the Institute of Problems of Chemical Physics, Russian Academy of Sciences.
Abstract: Aromatic polyazides are widely used as starting compounds in organic synthesis and for preparation of nitrogen—carbon nanomaterials and high-spin nitrenes. The latter have the strongest magnetic properties among organic polyradicals and are of considerable interest for studying molecular magnetism. The review summarizes the results of recent studies of aromatic polyazides and high-spin nitrenes carried out at the Institute of Problems of Chemical Physics, Russian Academy of Sciences.

Journal ArticleDOI
TL;DR: The structure-activity relationship revealed structural elements responsible for the arrhythmogenic and anti-arrhythmic properties of dipperpenoid alkaloids as discussed by the authors, and Allapinine (derived from the alkaloid lappaconitine) was approved as a drug.
Abstract: Diterpenoid alkaloids comprise a large group of natural compounds produced by the plants of the genera Aconitum and Delphinium. Some of these compounds were found to manifest valuable pharmacological properties, including the unique antiarrhythmic activity. Allapinine (derived from the alkaloid lappaconitine) was approved as a drug. The investigation of the structure—activity relationship revealed structural elements responsible for the arrhythmogenic and antiarrhythmic properties.

Journal ArticleDOI
TL;DR: In this paper, the properties of dichloride isopropoxide with a bidentate phenol alcohol ligand were investigated for ethene polymerization and shown to be catalytically active in the presence of the binary promoter Et2AlCl-MgBu2.
Abstract: Dinuclear (2) and mononuclear dichloride complexes (3) of titanium(iv) isopropoxide with a bidentate phenol alcohol ligand, viz., 2,4-di-tert-butyl-6-(1,1,1,3,3,3-hexafluoro-2-hydroxy-propan-2-yl)phenol, were obtained. The structures of the complexes were confirmed by X-ray diffraction. The dimeric structure of complex 2 is typical of alkoxy compounds and contains the bridging fragment Ti(μ-OPri)2Ti; the coordination polyhedron of the Ti atom is a distorted tetragonal pyramid. In complex 3, the Ti atom has a distorted octahedral environment made up of the O atoms of the ligand, the Cl atoms, and the O atoms of two coordinated propan-2-ol molecules. The catalytic properties of complexes 2 and 3 in ethene polymerization were studied with such promoters as polymethylaluminoxane (MAO), trimethylaluminum, triisobutylaluminum, diethylaluminum chloride, and Et2AlCl-MgBu2. Both the complexes were catalytically active (635 and 540 kg of polyethylene (PE)/(mol of Ti) h atm, respectively) only in the presence of the binary promoter Et2AlCl-MgBu2. The dichloride complexes obtained from a lithium or magnesium salt of the same ligand and TiCl4 without separation from lithium and magnesium chlorides formed as by-products were catalytically active in the presence of MAO, Bui 3Al, and Me3Al. For the catalytic system containing the dichloride complex and MgCl2, the best promoter is Me3Al (1082 kg of PE/(mol of Ti) h atm). The polymer obtained on all the catalytic systems is linear polyethylene characterized by high molecular weight (Mw = = 593900–2000000 g mol−1) and high polydispersity indices (Mw/Mn = 2.8–15). Various conjectures were made about why lithium and magnesium chlorides have the promoting effects.

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the works studying filtration combustion of solid fuels in the countercurrent mode and the phenomenon of superadiabatic overheating, and some results of the development of technological processes of production of thermal or electric energy from substandard raw materials and extraction of valuable components from unconventional sources.
Abstract: The works studying filtration combustion of solid fuels in the countercurrent mode are reviewed. The phenomenon of superadiabatic overheating is described. The data of experimental and theoretical studies and some results of the development of technological processes of production of thermal or electric energy from substandard raw materials and extraction of valuable components (for example, rare metals) from unconventional sources (industrial wastes, poor ores, burrows, etc.) are presented. The processes of safe treatment of problematic wastes are considered.

Journal ArticleDOI
TL;DR: In this paper, the effect of the gold particle size, temperature of the model gold catalyst, and NO pressure on the composition of the adsorption layer was studied by in situ XPS and STM methods.
Abstract: The effect of the gold particle size, temperature of the model gold catalyst, and NO pressure on the composition of the adsorption layer was studied by in situ XPS and STM methods. Adsorption of nitric oxide was carried out on gold nanoparticles with a mean size of 2–7 nm prepared on the thin film surface of alumina. In high-vacuum conditions (P NO ≈ 10−5 Pa), only atomically adsorbed nitrogen is formed on the surface of gold nanoparticles. At about 1 Pa pressure of NO and in the temperature range from 325 to 475 K, atomically adsorbed nitrogen coexists with the N2O adsorption complex. The surface concentration of the adsorbed species changes with a change in both the mean gold particle size and adsorption temperature. The saturation coverage of the surface with the nitrogen-containing complexes is observed for the sample with a mean size of gold particles of 4 nm. The surface of these samples is mainly covered with atomically adsorbed nitrogen, the saturation coverage of adsorbed nitrogen of about ∼0.6 monolayer is attained at T = 473 K. The change in the composition of the adsorption layer with temperature of the catalysts agrees with the literature data on the corresponding temperature dependence of the selectivity of N2 formation observed in the catalytic reduction of NO with carbon monoxide on the Au/Al2O3 catalyst. The dependences of the composition of the adsorption layer on the mean size of Au nanoparticles (size effect) and temperature of the catalyst are explained by the sensitivity of NO adsorption to specific features of the gold surface.

Journal ArticleDOI
TL;DR: In this article, the crystal and molecular structures of the CL-20 solvate with glyceryl triacetate and diethyleneglycol dinitrate were studied.
Abstract: Crystallization of CL-20 in different plasticizers (gyceryl triacetate and diethyleneglycol dinitrate) was studied. IR spectra of the crystals obtained under various conditions, as a rule, do not correspond to the spectra of known modifications. Crystal and molecular structures of the CL-20 solvate with glyceryl triacetate were studied. A new stable conformer of the CL-20 molecule was discovered.

Journal ArticleDOI
TL;DR: In this paper, a novel catalytic system was proposed for controlled radical polymerization of vinyl monomers based on the paramagnetic (17-electron) closo-complex, namely, 3,3-(dppb)-3-Cl-closo-3,1,2-RuC2B9H11 (1, dppb is 1,4-bis(diphenylphosphino)butane) and its mono(P-phenylene)- and di(P,P-ortho)-cycloboronated derivatives
Abstract: Novel catalytic systems were proposed for controlled radical polymerization of vinyl monomers. These systems are based on the paramagnetic (17-electron) closo-complex, namely, 3,3-(dppb)-3-Cl-closo-3,1,2-RuC2B9H11 (1, dppb is 1,4-bis(diphenylphosphino)butane) and its mono(P-phenylene)- and di(P,P-ortho-phenylene)cycloboronated derivatives, namely, (R = H, n = 10 (2); R = Me, n = 8 (3)) and (4). With the polymerization of methyl methacrylate as an example, the effect of the steric hindrances in complexes 1–4 on the synthesis and molecular-weight characteristics of the resulting polymers was analyzed. In the presence of aliphatic amines, the polymerization rate increases substantially and the catalyst concentration can be lowered without losing control of the process. The structure of 17-electron complex 3 in the solid state and its paramagnetic nature were confirmed by X-ray diffraction and ESR spectroscopy.

Journal ArticleDOI
TL;DR: The reactions of vanadyl sulfate VOSO4·3H2O with barium or strontium cyclopropane-1,1-dicarboxylate (MCpdc, M = Ba, Sr, H2Cpdc = C3H4(COOH)2) afforded the polymeric heterometallic complexes {[(H 2O)8Ba2(VO)2(VOSO 4·3HO2O]n (1) and {[H 2 O)6Sr(
Abstract: The reactions of vanadyl sulfate VOSO4·3H2O with barium or strontium cyclopropane-1,1-dicarboxylate (MCpdc, M = Ba, Sr, H2Cpdc = C3H4(COOH)2) afforded the polymeric heterometallic complexes {[(H2O)8Ba2(VO)2(Cpdc)4]·2H2O}n (1) and {[(H2O)6Sr(VO)(Cpdc)2]}n (2), respectively. These complexes differ in the binding mode of mononuclear vanadyl fragments with alkaline earth metal ions. Coordination polymers 1 and 2 were characterized by ESR spectroscopy.

Journal ArticleDOI
TL;DR: A series of new boron-containing tyrosine derivatives [B n H n−1O(CH2)4O-4-C6H4CH2CH-(NH3)COOH]− (n = 10, 12) were prepared by ring opening of the cyclic oxonium derivatives of the decahydro-closo-decaborate and dodecahydroid-dodecaborate anions, respectively, with ethyl Ntrifluoroacetyl-L-tyrosinate as discussed by the authors.
Abstract: A series of new boron-containing tyrosine derivatives [B n H n−1O(CH2)4O-4-C6H4CH2CH-(NH3)COOH]− and [B n H n−1O(CH2CH2)2O-4-C6H4CH2CH(NH3)COOH]− (n = 10, 12) were prepared by ring opening of the cyclic oxonium derivatives of the decahydro-closo-decaborate and dodecahydro-closo-dodecaborate anions, respectively, with ethyl N-trifluoroacetyl-L-tyrosinate

Journal ArticleDOI
TL;DR: In this article, a new method for the synthesis of benzotetrazine-1,3-dioxides was developed, which involves the reaction of 2-(tert-butyl-NNO-azoxy)-N-nitroanilines with the Ac2O/H2SO4 system.
Abstract: A new method for the synthesis of benzotetrazine-1,3-dioxides was developed, which involves the reaction of 2-(tert-butyl-NNO-azoxy)-N-nitroanilines with the Ac2O/H2SO4 system. This method was also used for the synthesis of [1,2,5]oxadiazolo[3,4-c]cinnoline-5-oxide from 3-nitramino-4-phenylfurazan. The suggested mechanism of these reactions involves the formation of the intermediate oxodiazonium ion, resulting from acetylation of the oxygen atom of the nitramine group, followed by protonation and ionic dissociation. Then the oxodiazonium ion enters the intramolecular reaction with the neighboring tert-butyl-NNO-azoxy or phenyl group to form the corresponding heterocyclic systems.

Journal ArticleDOI
TL;DR: In this paper, the ionic complexes simultaneously containing negatively charged coordination structures of metal phthalocyanines and fullerene anions, viz., {MnIIPc(CH3CH2S−) y·(I−)1−x.............. }·(C60.............. ·−)· ·(PMDAE+)2·C6H4Cl2 (PMDAEs), were obtained as single crystals, which made it possible to study their crystal structures.
Abstract: The ionic complexes simultaneously containing negatively charged coordination structures of metal phthalocyanines and fullerene anions, viz., {MnIIPc(CH3CH2S−) x ·(I−)1−x }·(C60 ·−)· ·(PMDAE+)2·C6H4Cl2 (PMDAE is N,N,N′,N′,N′-pentamethyldiaminoethane, x = 0.87, 1) and {ZnIIPc(CH3CH2S−)y·(I−)1−y }2·(C60 −)2·(PMDAE+)4·(C6H4Cl2) (y = 0.5, 2) were synthesized. The both compounds were obtained as single crystals, which made it possible to study their crystal structures. In complex 1, the fullerene radical anions form honeycomb-like layers in which each fullerene has three neighbors with center-to-center interfullerene distances of 10.13–10.29 A. Rather long distances between the C60 ·− radical anions results in the retention of monomeric C60 ·− in this complex down to the temperature of 110(2) K. In complex 2, fullerenes form dimers (C60 −)2 bonded by one C-C bond. The dimers are packed in corrugated honeycomb-like layers with interfullerene center-to-center distances of 9.90–10.11 A. Manganese(II) and zinc(II) phthalocyanines coordinate iodide and ethanethiolate anions to the central metal atom to form unusual negatively charged coordination structures MIIPc(An−) (An− is anion) packed in dimers {MIIPc(An−)}2 with a short distance between the phthalocyanine planes (3.14 A in 1 and 3.27 A in 2). The pthalocyanine dimers also form layers with the PMDAE+ cations, and these layers alternate with the fullerene layers. The packing of spherical fullerenes with planar phthalocyanine molecules is attained by the insertion of fullerenes between the phenylene groups of phthalocyanines. The π-π-interactions of the porphyrin macrocycle with five- or six-membered fullerene rings are characteristic of the earlier studied ionic porphyrin and fullerene complexes. Such interactions are not observed for ionic complexes 1 and 2.

Journal ArticleDOI
TL;DR: Ferromagnetic exchange interactions were found between the unpaired electrons of the paramagnetic centers in the exchange clusters of the gadolinium-containing heterometallic complexes {M-Gd-M} (M = Ni or Cu) as discussed by the authors.
Abstract: Trinuclear heterometallic complexes containing the {M2Ln(Piv)6(NO3)} (MII = Ni, Cu; LnIII = Nd, Pr, Sm, Eu, Gd; Piv− is the anion of pivalic acid) and {Cu2Ln(Piv)8)]− (LnIII = Eu, Gd) metal cores were synthesized, their structures and magnetic properties were studied. For the most compounds, it was shown that their magnetic properties can be interpreted taking no interaction of the 3d-metal ions and a lanthanide into account. Ferromagnetic exchange interactions were found to exist between the unpaired electrons of the paramagnetic centers in the exchange clusters of the gadolinium-containing heterometallic complexes {M-Gd-M} (M = Ni or Cu).

Journal ArticleDOI
TL;DR: C-Acylation of Meldrum’s acid by (het) Darylacetic acids in ethanol in the presence of 1,1′-carbonyldiimidazole leads to ethyl 4-(het)aryl-3-oxobutanoates in high yields.
Abstract: C-Acylation of Meldrum’s acid by (het)arylacetic acids in ethanol in the presence of 1,1′-carbonyldiimidazole leads to ethyl 4-(het)aryl-3-oxobutanoates in high yields.

Journal ArticleDOI
TL;DR: The results of analysis and refinement of phenomenological models for unimolecular reactions proceeding homogeneously in the bulk of undistorted crystal lattice or localized on the lattice defects are presented in this article.
Abstract: The results of analysis and refinement of phenomenological models for unimolecular reactions proceeding homogeneously in the bulk of undistorted crystal lattice or localized on the lattice defects are presented. It is shown that, within the framework of these models, the ratio of the rate constants for reactions in the liquid and solid phases, K = kl/ks, can be calculated with satisfactory accuracy and thus the known kl values can be used to predict the rate constant ks characterizing the stability of the materials.

Journal ArticleDOI
TL;DR: In this article, the reaction of 3-methyl-2,3-dihydro-4H-[1,4]benzoxazines in the reaction with chiral 2-arylpropionyl chloride predominantly yielded R*,R*-diastereomers.
Abstract: Kinetic resolution of racemic 3-methyl-2,3-dihydro-4H-[1,4]benzoxazines in the reaction with chiral 2-arylpropionyl chloride predominantly yielded R*,R*-diastereomers. Ibuprofen acyl chloride as acylating agent was found to be more selective and sensitive to the changes in the reaction temperature as compared to naproxen acyl chloride and 2-phenylpropionyl chloride.

Journal ArticleDOI
TL;DR: In this paper, a procedure was developed for the synthesis of the kinetically stable nitroxide 2-(Ntert-butyl-N-hydroxyamino)-4,4,5,5-tetramethyl-4, 5-dihydro-1H-imidazole-3-oxide-1-oxyl containing the sterically hindered hydroxylamino group.
Abstract: A procedure was developed for the synthesis of the kinetically stable nitroxide 2-(N-tert-butyl-N-hydroxyamino)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl containing the sterically hindered hydroxylamino group. The crystal and molecular structure of this compound was determined. The isolation of this nitroxide hydroxylamine in the individual state enabled a new procedure for the preparation of its oxidation product, viz., the corresponding nitroxide biradical. The results of quantum chemical calculations of the electron exchange in the biradical molecule are in good agreement with the experimental data on the triplet ground state of the molecule in the crystal obtained earlier.

Journal ArticleDOI
TL;DR: In this paper, the hitherto unknown dihydrothiaselenine (III) was obtained together with polymerization products by nucleophilic substitution and subsequent ring expansion to furnish the previously unknown Dihydrothia elenine.
Abstract: Thiaselenole derivative (I) rearranges by nucleophilic substitution and subsequent ring expansion to furnish the hitherto unknown dihydrothiaselenine (III), obtained together with polymerization products.

Journal ArticleDOI
TL;DR: In this article, a simplified unidimensional one-temperature mathematical model was proposed for the description of stationary regimes of filtration combustion of solid fuels, and the model qualitatively characterizes the dependence of the combustion regime on the main controlling parameters and makes it possible to reveal the critical conditions for the existence of stationary combustion regimes.
Abstract: The dependences of the temperature and the rate of filtration combustion (FC) of carbon on the main parameters controlling the process were experimentally and theoretically studied. Among these are the fraction of the combustible in the charge, the flow rate of the oxidant, the reactivity of the carbon material, and the level of heat loss via the reactor walls. The transition from the conditions of stationary propagation of the combustion wave to decay occurs critically, upon a minor change in the controlling parameters. The parametric domain of the stationary wave was determined. A simplified unidimensional one-temperature mathematical model was proposed for the description of stationary regimes of FC of solid fuels. The model qualitatively characterizes the dependence of the combustion regime on the main controlling parameters and makes it possible to reveal the critical conditions for the existence of stationary combustion regimes.

Journal ArticleDOI
TL;DR: The reactivities of gem-dichlorobicyclo[n.1.0]alkanes depend on their spatial structures, sharply decreasing with an increase in the number of the methylene units in the bicyclic molecule as mentioned in this paper.
Abstract: Nitrosation of gem-dichloro(alkyl)cyclopropanes with the complex NOCl·2SO3 gave regioisomeric alkyl-5-chloroisoxazoles in high yields; a similar reaction with 1,2-bis(gem-dichlorocyclopropyl)ethane afforded the corresponding bis(5-chloroisoxazoles). The reactivities of gem-dichlorobicyclo[n.1.0]alkanes depend on their spatial structures, sharply decreasing with an increase in the number of the methylene units in the bicyclic molecule.