On the Reactivity and Stability of Iodide–Nitride–Sulfide Clusters of Neodymium and Dysprosium

The thermal decomposition of cluster Nd₃I₅(S₂)(S₂N₂)(THF)10 (I) at 50–400°C affords a mixture of products among which tetrahydrofuran (THF), sulfur, diiodine, HI, H₂S, CS₂, S₃N₆, S₃N₅, MeI, thiophene, tetrahydrothiophene, diiodobutane, iodobutene, and NdI₃ are identified. The treatment of Ln₃I₅(S₂)(S₂N₂)(THF)₁₀ (Ln = Nd (I), Dy (II)) with phenanthroline (Phen) in THF at room temperature results in the partial substitution of ТНF to form new complexes Ln₃I₅(S₂)(S₂N₂)(THF)₄(Phen)₃. The dissolution of compound I in pyridine gives a pyridine (Py) complex Ln₃I₅(S₂)(S₂N₂)(THF)3(Py)₇. The dissolution of compounds I and II in acetonitrile at 20°C is accompanied by the fast rearrangement and fragmentation of the complexes to form LnI₃(MeCN)₆, [LnI(S₂)(MeCN)], and [LnI(S₂N₂)(MeCN)]. Complex I in THF does not react with white phosphorus, carbon monoxide, fullerene C₆₀, and chromium hexacarbonyl.     

Dynamics of the BiTeI lattice at high pressures

Raman measurements of the phonon spectrum of BiTeI at pressures of up to 20 GPa have been performed. A decrease in the linewidth of E² vibration by almost a factor of 2 with an increase in the pressure to 3 GPa has been detected. The frequencies of all four Raman active modes increase monotonically with the pressure. These lines are observed in spectra up to ～8 GPa. Sharp change in the spectrum occurs at pressures of 8–9 GPa, indicating a transition to the high-pressure phase, which holds up to 20 GPa. This transition is reversible and hardly has any hysteresis. A sample in the high-pressure phase is single crystal.     

Heterocyclization of electrophilic alkenes with tetranitromethane revisited: regiochemistry and the mechanism of nitroisoxazole formation

Revised regiochemistry for the heterocyclization of electrophilic alkenes with tetranitromethane (TNM) in the presence of triethylamine, providing rapid access to nitroisoxazoles, is reported. The formation of 5-nitroisoxazoles previously incorrectly assigned as 3-nitro regioisomers, has now been established unambiguously by X-ray crystallography. Empirical computations with ACD/CNMR Predictor, based both on hierarchical ordering of spherical environments (HOSE) and an algorithm of artificial neural networks (ANN), and also Density Functional Theory computations of the ¹³C NMR chemical shifts for the 3- versus 5-nitroisoxazoles are shown to consistently match the spectra of the experimentally observed 5-regioisomers.     

Estimation of the initial shape of meteoroids based on statistical distributions of fragment masses

An approach to the estimation of the initial shape of a meteoroid based on the statistical distributions of masses of its recovered fragments is presented. The fragment distribution function is used to determine the corresponding scaling index of the power law with exponential cutoff. The scaling index is related empirically to the shape parameter of a fragmenting body by a quadratic equation, and the shape parameter is expressed through the proportions of the initial object. This technique is used to study a representative set of fragments of the Bassikounou meteorite and compare the obtained data with the results of statistical analysis of other meteorites.     

Synthesis and properties of porous silica obtained by the template method

Micromesoporous samples of SiO₂ were synthesized by the sol-gel method using tetraethoxysilane as a starting reagent and 1–5 wt % cetylpyridinium chloride as a template under the conditions of preadsorption of colloid silica by polyethyleneglycol macromolecules. The adsorption and texture of the samples were studied by the low-temperature nitrogen adsorption-desorption technique. Preadsorption of silica sol was shown to affect the adsorption and capillary-condensation properties of silica. The surface area and the volume of mesopores increased at cetylpyridinium concentrations higher than 1 wt %. The micropore volume increased to a maximum. The capillary-condensation hysteresis loop of H4 type transformed into an H3 loop according to the IUPAC classification.     

Synthesis of substituted 1-[2-(adamantan-1-yl)ethyl]piperidines

Quaternary 1-[2-(adamantan-1-yl)ethyl]pyridinium bromides were reduced with sodium tetrahydridoborate in ethanol, and hydroarylation of the resulting 1-[2-(adamantan-1-yl)ethyl]-1,2,3,6-tetrahydropyridines with benzene in trifluoromethanesulfonic acid afforded phenylpiperidines with preferentially equatorial orientation of the phenyl substituent.     

Spectral-kinetic evidence of interaction of photochromic diarylethenes with silver nanoparticles

Spectral-kinetic investigations of the photochromism of some diarylethenes with sulfur-containing substituents in dimethylsulfoxide solutions with and without silver nanoparticles are performed. It is shown that silver nanoparticles chemically interact with diarylethene molecules, which is manifested in a change in the spectral and kinetic characteristics and photodegradation efficiency.     

Electrophysical and acoustic properties of magnetic elastomers structured by an external magnetic field

Magnetoactive elastomers are promising for use in designing of magnetically operated devices for signal processing and sensors. The results from studying the electrophysical and acoustic properties of new magnetoactive elastomers structured by a nonuniform magnetic field are presented. It is shown that the prestructuring of the magnetic disperse filler by a magnetic field during composite synthesis substantially improves the coefficient of the transmission of electromagnetic radiation through the sample. The effect gets stronger as the mass fraction of filler increases. As the filler concentration grows, the transmission coefficient falls by 50%, and the ref lection coefficient grows by a factor of 150%. The longitudinal elastic modulus and the density vary within the ranges of 1.4–1.8 GPa and 2485–3362 kg m^–3, respectively, depending on the magnetic filler concentration and the sample’s structuring. The obtained results demonstrate the potential of usinf structured magnetoactive elastomers as radar absorbing materials.     

Synthesis of 4(6)-aryloxy- and 4-arylthio-2,1,3-benzoxadiazoles

Reactions of 4,6-dibromo-2,1,3-benzoxadiazole with phenols or arenelthiols lead to 4-aryloxy-6-bromo-2,1,3-benzoxadiazoles or 4-arylthio-6-bromo-2,1,3-benzoxadiazoles, respectively. Isomeric 6-aryloxy-4-bromo-2,1,3-benzoxadiazoles were synthesized by replacement of the fluorine atom in 2,6-dibromo-4-fluoro-1-nitrosobenzene with phenols and treatment of the resulting 4-aryloxy-2,6-dibromo-1-nitrosobenzene with sodium azide.     

Sorption Selectivity of Palladium(II) by Poly(N-2-Sulfoethylallylamine) under Static and Dynamic Conditions

Russian Journal of Applied Chemistry - The process of Pd(II) sorption from hydrochloric acid solutions was studied in the pH range of 0.5–5.0 in the presence of Pt(IV) and a number of...