U.A. Soliman
Al Azhar University, Nasr City, Cairo, Egypt
Keywords: 1,3-dimethyluracil, normal coordinate analysis, vibrational frequencies, ab initio calculation, internal rotation barriers
The molecular structure of 1,3-dimethyluracil (C6H8N2O2; 1,3-DMU) is studied theoretically and experimentally using Gaussian 98 calculations and different spectroscopic techniques. The vibrational spectrum for 1,3-DMU in the solid phase is recorded in the IR range 4000-400 cm-1. Initially, in order to get the most stable structure, twelve structures were proposed for the titled compound as a result of the internal rotation of CH3 around C-N bonds and keto-enol tautomerism. The single point energy and frequency calculations are obtained by MP2 (Full) and DFT/B3LYP methods with the 6-31G( d ) basis set using the Gaussian 98 computation package. After the complete relaxation of twelve isolated isomers, the ( diketo ) tautomer was the only favored structure owing to its low energy relative to the other isomers and the prediction of real frequencies. This interpretation is supported by the recorded infrared spectrum that shows the presence of only the diketo tautomer. Aided by the normal coordinate analysis and potential energy distributions, a confident vibrational assignment of the fundamental frequencies is calculated. The results are discussed herein and compared with similar molecules whenever possible.
N. S. Nesterov1, I. I. Simentsova1, V. F. Yudanov1, O. N. Martyanov1,2 1Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: сверхкритические флюиды, ФМР, гетерогенные катализаторы процесса ФишераТропша, восстановление, in situ, supercritical fluids, FMR, heterogeneous catalysts for the FischerTropsch process, reduction, in situ
An in situ comparative study of the reduction of Co-containing catalysts for the Fischer-Tropsch process in hydrogen and supercritical (SC) isopropanol is performed by ferromagnetic resonance (FMR) spectroscopy. According to the FMR data, the reduction of cobalt-containing oxide particles to metal in hydrogen starts at temperatures of ~360°C, which is substantially lower than a temperature of the formation of metal particles of the active phase according to powder X-ray diffraction and differential thermogravimetry data ( Т ~ 450°C). In SC isopropanol, the reduction to Co metal occurs at lower temperatures ( T ~ 245°C) as compared with the reduction temperature for these catalysts in hydrogen. It is shown that the reduction in SC isopropanol can lead to the formation of superparamagnetic Co nanoparticles with a narrow particle size distribution.
N. I. Giricheva1, G. V. Girichev2, V. M. Petrov1 1Ivanovo State University, Ivanovo, Russia 2Ivanovo State University of Chemistry and Technology, Ivanovo, Russia
Keywords: масс-спектр, молекулярная структура, производные нафталинсульфокислоты, нафталинсульфонилхлориды, нафталинсульфонилфторид, нафталинсульфонамиды, пути фрагментации, mass spectrum, molecular structure, naphthalenesulfonic acid derivatives, naphthalenesulfonyl chlorides, naphthalenesulfonyl fluoride, naphthalenesulfonamides, fragmentation paths
By mass spectrometry it is found that naphthalene, 1-naphthalenesulfonyl chloride, 2-naphthalenesulfonyl fluoride, 2-naphthalenesulfonyl chloride, 1,5-naphthalenedisulfonyl chloride, 1-naphthalenesulfonamide, and 2-naphthalenesulfonamide evaporate congruently on heating and their saturated vapor is presented by the corresponding monomeric molecular forms. The relationship is established between the character of the fragmentation of molecules during electron ionization and the specific features of their geometric and electronic structures.
S. V. Shevkunov
Peter the Great St. Petersburg Polytechnic University, St.Petersburg, Russia
Keywords: гидратация ионов, структура гидратной оболочки, наноструктуры, супрамолекулярные структуры, термодинамическая устойчивость молекулярной структуры, компьютерное моделирование на молекулярном уровне, метод Монте-Карло, hydration of ions, hydrate shell structure, nanosized structures, supramolecular structures, thermodynamic stability of a molecular structure, computer simulation at the molecular level, Monte Carlo method
The structure and stability of hydrate shells of singly charged sodium and chlorine ions are studied by computer simulations under the conditions of nanoscopic flat pores with the use of the previously proposed detailed force field model containing polarization interactions, transferring charge effects as well as many-body interactions of covalent type. It is found that the effect of ousting a monatomic ion from its hydration shell, which has previously been observed by independent authors in bulk vapor, is also reproduced persistently in nanoscopic pores. Whereas the ousting of the ion from its hydration shell in bulk vapor is accompanied by the loss of thermodynamic stability of the system and at sufficiently high vapor pressure causes avalanche-like condensation, under the conditions of a nanoscopic pore the thermodynamic stability is retained. The obtained data show that the ousting of the ion from its hydration shell is a universal phenomenon covering the majority, if not all, of monatomic and, possibly, some of molecular ions.
a:2:{s:4:"TYPE";s:4:"TEXT";s:4:"TEXT";s:99:"O. M. Yakovenko, V. P. Kazimirov, A. S. Roik, N. V. Golovataya, S. P. Yaltanskii†, V. E. Sokol’skii";}
Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
Keywords: расплав Al-Ge, микрогетерогенная структура, рентгеновская дифракция, ближний порядок, Al-Ge melts, microheterogeneous structure, X-ray diffraction, short-range order
An X-ray diffraction study is performed of the structure of Al-Ge melts containing 0 at.%, 10 at.%, 20 at.%, 30.3 at.%, 40 at.%, 50 at.%, 60 at.%, 70 at.%, 80 at.%, and 100 at.% Ge near the liquidus line at 1273 K. The melts containing 40 at.%, 70 at.%, and 80 at.% Ge are studied in the temperature range up to 1823 K. The structural factor (SF) curves of the melts have a shoulder on the high-angle side of the first maximum at contents above 20 at.% Ge; the position of the shoulder coincides with that on the SF curve of liquid germanium. An increase in temperature leads to gradual smoothening of the shoulder because of the increase in the structural homogeneity of the melts, which is attributed to the metallization of the residual covalent bonds between germanium atoms. The structure of the melts is found to be microheterogeneous for germanium contents above 20 at.%, which is due to the coexistence of microclusters of liquid germanium and those of the melt with 20 at.% Ge, which provides a satisfactory description of the experimental SF curves in the concentration range 20-100 at.% Ge at temperatures near the liquidus line.
N. A. Atamas
National Taras Shevchenko University of Kyiv, Kyiv, Ukraine
Keywords: ионные жидкости, одноатомные спирты, энергия межмолекулярного взаимодействия, молекулярная динамика, локальная структура, радиальные функции распределения, водородные связи, дипольный момент, ionic liquids, monohydric alcohols, intermolecular interaction energy, molecular dynamics, local structure, radial distribution functions, hydrogen bonds, dipole moment
The method of molecular dynamics is used to investigate the effect of monohydric alcohols on the formation of the local structure of ionic liquids based on the dimethylimidazolium cation at T = 400 K. The intermolecular interaction energies are analyzed to find that the increase in the length of the alkyl chain in the alcohol molecule reduces the influence of the solute molecule on the formation of the local structure of the dmim+/Cl--solute molecule systems. An analysis of the radial distribution function shows that the change in the structure and physical characteristics of the solute molecule does not affect the interaction between the hydroxyl group proton of the alcohol molecule and the ionic liquid anions, whose interactions form the hydrogen bond Halcohol…Cl- with a length of 2.3 Å.
V. P. Korolev1,2 1Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia 2Ivanovo State University of Chemistry and Technology, Ivanovo, Russia
Keywords: кажущиеся и парциальные объемы, гидратные числа ионов, хлорид аммония, нитрат аммония, apparent and partial volumes, hydration numbers of ions, ammonium chloride, ammonium nitrate
A method is proposed for determining the hydration number of an individual ion within the approach (V. P. Korolev, J. Struct. Chem. , 55, No. 3, 463 (2014)). In an infinitely dilute solution, the hydration numbers of ions are given by the formulas NH4+(H2O)2, Cl-(H2O)4, and NO3-(H2O)7. The structure of aqueous complexes is discussed, and a structurally relevant parameter, i.e., the density of water of hydration, is determined. Salt concentration dependences are derived for the hydration number and apparent volume of NH4+, Cl-, and NO3- ions. The density of the cationic (Н2О-NH4+) and anionic (Н2О-Cl- and Н2О-NO3-) systems is calculated.
S. A. Gromilov1,2, A. P. Tyutyunnik3, D. A. Piryazev1,2, P. E. Plyusnin1,2, S. V. Korenev1,2 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia 3Institute of Solid State Chemistry, Urals Branch, Russian Academy of Sciences, Ekaterinburg, Russia
Keywords: медь, перренат, термолиз, рентгенофазовый анализ, рентгеноструктурный анализ, кристаллохимия, copper, perrhenate, thermolysis, powder X-ray diffraction analysis, single crystal X-ray diffraction analysis, crystal chemistry
The X-ray in-situ study of [Cu(NH3)4](ReO4)2 complex salt is carried out on heating up to 500 K. The product obtained at this temperature is a new crystalline phase [Cu(NH3)2(m-ReO4)2] n with the following unit cell parameters: a = 14.7523(3) Å, b = 5.8559(1) Å, c = 5.6290(1) Å, b = 111.387(1)°, V = 452.799(2) Å3, space group C 2/ m , Z = 2, dx = 4.386 g/cm3. The coordination polyhedron of the Cu atom is a distorted octahedron formed by two nitrogen atoms (Cu-N 2.195 Å), and four oxygen atoms (Cu-О 2.306 Å). The structure consists of infinite [Cu(NH3)2(m-ReO4)2] n chains, the shortest N(H)…O distances between the chains being 2.82 Å.
T. A. Rodina1, O. V. Loseva1,2, A. I. Smolentsev3, A. V. Ivanov2 1Amur State University, Blagoveshchensk, Russia 2Institute of Geology and Nature Management, Far Eastern Branch, Russian Academy of Sciences, Blagoveshchensk, Russia 3Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: диалкилдитиокарбаматы цинка со свойствами хемосорбентов, формы связывания золота из растворов, гетероядерные комплексы золота(III)-цинка, кристаллическая и молекулярная структура, РСА, синхронный термический анализ, электронная растровая микроскопия и рентгеноспектральный микроанализ, zinc dialkyldithiocarbamates with chemisorption properties, binding forms of gold from solutions, heteronuclear gold(III)-zinc complexes, crystal and molecular structure, X-ray crystallography, synchronous thermal analysis, scanning electron microscopy, X-ray spectral microanalysis
Structural organization and thermal behavior of a new polymeric heteronuclear of gold(III)-zinc-dibutylammonium complex ([NH2(C4H9)2][Au{S2CN(C4H9)2}2][ZnCl4]) n (I), obtained by a heterogeneous reaction between freshly precipitated binuclear zinc dibutyldithiocarbamate [Zn2{S2CN(C4H9)2}4] and a H[AuCl4] solution in 2M HCl, is studied. According to single crystal XRD data the crystal structure of the obtained compound is determined and its main structural units are complex [NH2(C4H9)2]+ and [Au{S2CN(C4H9)2}2]+ cations and complexе [ZnCl4]2- anions. Dibutylammonium cations are hydrogen bonded to tetrachlorozincate ions, forming zigzag polymer chains. On the side of the chains there are discrete complex [Au{S2CN(C4H9)2}2]+ cations characterized by a planar tetragonal structure and a uniform spatial orientation. The thermal behavior of I is investigated by synchronous thermal analysis. The multistage process of thermal destruction involves the thermolysis of the cation and anion parts (with the release of metallic gold, zinc chloride and a partial formation of zinc sulfide).
Three new complexes [Cd(Hflu)2(NO3)](NO3) 1, [Cd(H2O)(Hflu)2(Hmalo)](NO3)×2(H2O) 2, and [Cd(H2O)(Hflu)2(Hfum)](NO3)×2(H2O) 3 (Hflu = [2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)-propan-2-ol], H2fum = fumaric acid, H2malo = malonate acid) are synthesized by a solution diffusion method and characterized by single crystal X-ray diffraction methods, elemental analyses, IR spectroscopy as well as thermal analyses. In compound 1, Cd(II) cations are bridged by fluconazole ligands to form 2D Cd-Hflu layers, and these layers are further connected by C-H⋯F hydrogen bonds to form a complicated 3D structure with the topology of (4×6×8)(4×64×84×10)(6×3). Compounds 2 and 3 are isostructural, and in them the Cd(II) cations are bridged by fluconazole ligands to form a 2D network, which is connected by C-H⋯O hydrogen bonds to form a complicated 3D (3,4)-connected framework with the topology of (4×82)(4×85).
