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[en] Comparison of the properties of high-temperature superconductors with those of chemical systems where a periodical (oscillating) redox reaction is realized suggests that the high-temperature superconducting of nonclassical superconductors (in particular, ternary oxides) results from activation of a periodical redox reaction within a single compounds containing heterovalent forms of each of two dissimilar elements. In this redox reaction, reversible converison of the corresponding heterovalent forms occur. 37 refs., 1 fig., 1 tab
[en] The standard enthalpies of formation of uranium-containing compounds M1AsUO6 at 298.15 K (M1=Li, Na, K, Rb, and Cs) were calculated according to Hess' law from the standard enthalpies of the corresponding reactions. The standard enthalpies of dehydration of the compounds studied were calculated from the data obtained. 9 refs
[en] The reaction of 5-aminomethyl-4-(1,2,3-thiadiazol-4-yl)furan-2-carboxylic acid ethyl ester with bases has given ethyl 5-sulfanylidene-4,5,6,7-tetrahydrofuro[2,3-c]pyridine-2-carboxylate as a result of intramolecular 6-endo-dig-cyclization of thioketene generated in situ with an internal CH2NH2 nucleophile. The obtained ester has been alkylated with iodomethane at the sulfur atom to form ethyl 5-methylsulfanyl-4,7-dihydrofuro[2,3-c] pyridine-2-carboxylate. The Hantzsch reaction with ω-bromoacetophenone has resulted in the formation of 7-ethoxycarbonyl-3-phenylfuro[3,2-d[1,3]thiazolo[3,2-a]pyridin-4-ium bromide.
[en] The processes of unsaturated cyclic hydrocarbons hydrogenation in a three-phase gas-liquid-solid catalyst system in the presence of nanostructured nickel, cobalt, or iron catalysts in a flow reactor at 130°C and atmospheric pressure have studied. RX3Extra activated carbon, γ-Al2O3, NaX zeolite, and Purolite CT-175 cation-exchange resin have been used as supports; NaBH4 and NH2NH2·H2O were used as reducing agents. The catalytic activity of supported nanoparticles and their selectivity with respect to the product of exhaustive hydrogenation have been investigated.
[en] The structure of the products of anodic oxidation of triphenylphosphine in the presence of camphene carried out in acetonitrile with sodium perchlorate as supporting electrolyte has been studied. The major product, triphenylphosphine oxide, has been isolated from the solution in the form of cocrystals of free triphenylphosphine oxide and its complex with sodium perchlorate. The molecular structure of the cocrystals has been studied by X-ray diffraction analysis. Triphenylcamphenylphosphonium perchlorate, bornylacetamide, and a terpene compound with triphenylphosphonium and acetamide substituents in the cycle have been detected by NMR 13C as the electrolysis side products.
[en] The reaction of 6-amino-3-methyl-4-(2,4-dichlorophenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile with phosphorus sulfide in boiling pyridine unexpectedly leads to the formation of a not previously described heterocyclic system—[1,2]oxaphosphinino[6,5-c]pyrazole derivative. Structure of the obtained compound was proved using 2D NMR spectroscopy and X-ray diffraction analysis.
[en] A Schiff base containing the nitrogen-sulfur donor chain [(CH3)2N-C6H4-CH=N-NH-C(S)-SCH2C6H5] was prepared by the condensation of 4-(dimethylamino)benzaldehyde and S-benzyldithiocarbazate and coordinated with Ni(II), Cu(II), and Zn(II). The Schiff base and its metal complexes were characterized by elemental analysis, IR, 1H and 13C NMR, electronic absorption spectroscopy and some of their physicochemical properties were determined. The Schiff bases behaved as a bidentate uninegative ligand in all the complexes, giving square-planar geometrical structures with Ni(II) and Cu(II) and a tetrahedral structure with Zn(II). The Schiff base and its complexes were screened for antibacterial activity. The biological activity testing results showed that the complexes were more potent antibiotics than the free ligand. The Cu(II) and Ni(II) complexes displayed high antibacterial potency and Zn(II) was moderately active against bacteria.
[en] Experimental data and results of quantum chemical calculations on the structure and thermodynamic properties of inorganic associates in a high-temperature vapor were systematized. A criterion for thermal stability was proposed, and the dependences of the atomization enthalpies of these compounds on the atomization enthalpies of the anion-forming fragment were revealed.
[en] Density functional theory method UB3LYP*/6-311++G(d,p) has been applied to the study of geometry, energy, and magnetic characteristics of the isomers of trinuclear complexes FeII-MII-FeII (M = Co, Ni, Cu, Zn) designed from two terminal iron-containing fragments connected via a linker based on bis-salicylaldiminate of transition metal functionalized with 1,10-phenanthroline. It has been shown that the investigated complexes are capable of two-step spin crossover on iron ions. In the systems with cobalt and nickel bis-chelates, the possibility of intramolecular rearrangements via the mechanism of configurational isomerism has been predicted.
[en] Novel quinoxaline derivatives have been synthesized via the reaction of 3-trifhioromethyl-1,2,3-propanetrione-2-oximes with 1,2-diaminobenzene or 2,3-diaminonaphthalene: 2-trifluoromethyl-3-aroylquinoxaline and 2-trifluoromethyl-3-aroylbenzo[g]quinoxaline. Under similar conditions, 3-RF-1,2,3-propanetrione-2-oximes [RF = C3F7, H(CF2)4, C4F9, and C6F13] with the same diaminoarenes have given a mixture of the condensation and fragmentation products in different ratios. The structure of (4-methylphenyl)[3-(tri-fluoromethyl)benzo[g]quinoxalin-2-yl]methanone has been elucidated by means of X-ray diffraction analysis.