Formation of SO−2, SO2·O− and SO2·SO− by electron attachment to van der waals SO2 clusters

SO⁻₂, SO₂·O⁻ and SO₂·SO⁻ are produced by electron attachment to SO₂ clusters under single collision conditions. SO⁻₂, which is not produced at all in low-pressure ion sources, is more abundant than SO₂·O⁻ and SO₂ ·SO⁻. Measured relative attachment cross sections for these ions show significant differences when compared to O⁻ and SO⁻ produced by attachment to SO₂, i.e. the first resonance is very efficiently quenched in favor of SO⁻₂ production. This is in contrast to previous findings in O₂, CO₂ and N₂O.     

The pre-resonance raman effect of the species I−·SO2 and SCN−·SO2

The Raman spectra of the solvated ions I⁻·SO₂ and SCN⁻·SO₂ were obtained using several exciting wavelengths. The excitation profiles show a pre-resonance enhancement of the SO₂ symmetric stretching mode in the solvates as the exciting frequency approaches the corresponding electronic transition frequency in the near UV. Such behavior and the presence of the overtone of the enhanced mode strongly indicate the charge transfer nature of the interaction between the ions and sulfur dioxide in the solvates.     

Studies on SO 4 2− Ion Incorporation into Apatite Structure

Calcium sulphate-apatites were synthesised by precipitation from aqueous solutions with different fluorine content and analyzed by chemical, x-ray diffraction (XRD), Raman, and Fourier transform infrared (FTIR) analyses. Their thermal stability was studied by differential scanning calorimetry (TG/DSC) and high-temperature XRD. It was established that the introduction of SO 4 2 m into apatite structure and the thermal changes depend on the fluorine content in the apatite structure. At temperatures above 600;C the structure of apatite reorganizes and CaSO 4 forms a separate phase.     

Thermochemical investigations of the systems KCl−KBr−H2O,K2SO4−(NH4)2SO4−H2O and KNO3−NH4NO3−H2O at 298.15 K

For the equilibrium solid phases occurring in the systems: KCl?KBr?H₂O, K₂SO₄?(NH₄)₂SO₄?H₂O and KNO₃?NH₄NO₃?H₂O, the concentration dependencies of differential solution enthalpies, Δ_sol H ₂ for several crystallization paths, were measured. The limiting differential solution enthalpies, Δ_sol H ₂ ⁰ , were determined by extrapolation of the above dependencies to the ionic strength,I _m ⁰ , corresponding to the appropriate binary solutions. For KCl?KBr?H₂O system only, the clear dependence between Δ_sol H ₂ ⁰ andI _m ⁰ values was found and discussed.     

Three-body dissociation dynamics of (SO2)3 studied through dissociative photodetachment of (SO2)3−

The dissociative photodetachment dynamics of (SO₂)₃⁻ were studied by photoelectron–photofragment coincidence spectroscopy at 258 nm. Correlation between the photoelectron and photofragment translational energies was observed as previously seen in the dimer system, implying the presence of a dimer core. The three-body dissociation dynamics of (SO₂)₃ after photodetachment are consistent with a dimer core solvated by a spectator SO₂ molecule with a broad distribution in initial geometry.     

The new synthesis of sulfuryl-bridged triazinane and its selective recognition to SO42−

Research on Chemical Intermediates - A new method has been developed for the synthesis of a cage-like sulfuryl-bridged triazinane molecule HEXS by acidic condensation of a glycoluril analog with...     

The conformational changes of 5SrRNA from lupin seeds in presence of ClO 4 − , NO 3 − , Br−, BF 4 − , SO 4 2− , Cl−, COO− anions by adiabatic scanning calorimetry

The results of calorimetric studies of 5SrRNA solutions isolated from lupin seeds in the pressence of the ClO ₄ ^? , NO ₃ ^? , Br ₄ ^? , SO ₄ ^2? , Cl^?, COO^? (maleic and fumaric acids) anions were reported. The plots of calorimetric curves, enthalpy of conformational changes of two state transitions were presented. Using the deconvolution method proposed by Freire and Biltonen the elementary transitions were distinguished and discussed.     

Electronic structure and spectra of [Fe(CN)6SO3]4−

The complex ion [Fe(CN)₆SO₃]⁴⁻ has been prepared in aqueous solution and as the zinc salt in the solid state. The electronic and IR spectra of the complex ion (I) have been recorded. MO calculations have been performed to understand the electronic structure of complex I. The electronic spectra of I and hexacyanoferrate(II) [HCF(II)] have been calculated and compared with the experimental results for I, HCF(II) and HCF(III). The experimental and theoretical results suggest that the oxidation state of Fe in I is + 3 and not +2 and the SO₃ moiety is bonded to one of the nitrogen atoms of the cyano group.     

Untersuchungen in den Systemen: V−B,Nb−B,V−B−Si und Ta−B−Si

Zusammenfassung Mit Hilfe röntgenographischer Messungen werden die Boride von Vanadin und Niob untersucht, wobei eine neue Phase der ungefähren Zusammensetzung V₂B identifiziert wird, welche mit der entsprechenden Nb-Borid-Phase isotyp ist. Dieselbe Kristallart tritt auch im System: Ta–B auf. Die in der Literatur angegebene -Phase im Zweistoff: Nb–B erweist sich als NbO.Im System: V–B–Si wird wie im analogen Mo-System die Existenz einer ternärenT 2-Phase Me₅(Si_1/3, B_2/3)₃ nach-gewiesen¹; ihre Gitterkonstanten werden ermittelt.Im Schnitt Ta₂Si–Ta₂B besteht ein geringes Lösungs-vermögen der beiden Phasen ineinander. Durch Zusatz von 20 Mol-% Ta₂Si zu Ta₂B erhält man die oben erwähnte neue Kristallart.Bei den Borid-Siliziden der Metalle aus der 4a-, 5a- und 6a-Gruppe werden die Stabilitätsbereiche derT 1-,T 2- undD 8₈-Phasen miteinander verglichen.     

Untersuchungen in den Dreistoffen: Cr−W−Si und Mo−W−Si

Zusammenfassung Der Schnitt: Me₃Si (Me=Cr, W bzw. Mo, W) wird an Hand heißgepreßter und in Argon homogenisierter Legierungen untersucht; es läßt sich weder das metastabile W₃Si, noch eine W-reiche Mischphase von diesem Typ beobachten. Cr₃Si nimmt bei 1500°C etwa 20 Mol%, W₃Si auf, während Mo₃Si selbst bei 1900°C praktisch kein W₃Si löst (ev. wenige Mol%). Dagegen bestehen lückenlose Mischreihen zwischen den Me₅Si₃-Phasen mit W₅Si₃-Typ. Die grundsätzliche Aufteilung der Phasenfelder ist damit möglich.Mit 2 Abbildungen     

Magnetische Messungen an den Teilsystemen TiC−ZrC,TiC−HfC,ZrC−HfC,TiC−VC,TiC−NbC,TiC−TaC und NbC−TaC

Ohne ZusammenfassungMit 3 Abbildungen     

The state of metals in the supported bimetallic Pt−Pd/SO4/ZrO2 system

The behavior of the metals in the Pt−Pd/ZrO₂ and Pt−Pd/SO₄/ZrO₂ systems was studied by DRIFT spectroscopy. After reduction of Pt−Pd/ZrO₂ at 100 °C, the states of the metals are mainly Pt⁰ and Pd⁰ with a minor admixture of positively charged forms of Pt⁺ or Pd²⁺. An increase in the temperature of reduction leads to the formation of a bimetallic alloy. In the Pt−Pd/SO₄/ZrO₂ system, the effects of alloy formation and the interaction of the surface SO₄ groups superimpose. At low reduction temperatures, the surface SO₄ groups interact mainly with palladium. The influence of the surface sites on both supported metals increases with increasing reduction temperature. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1265–1270, July, 1999.     

Lack of salt effect on the kinetics of the reaction SO2−4 + H3O+ → HSO−4 + H2O

It is found that the broadening of the 1100-cm⁻¹ line of SO⁻²₄, caused by increasing [H₃O⁺], is unaffected by addition of 4 M LiCl, NaBr, KCl and NH₄Cl. This finding is in line with the lack of influence of NaCl reported earlier. The significance of these findings, in terms of the reaction mechanism, is discussed.     

Magnetische Kernresonanzuntersuchungen an Ti−C−H-Legierungen

Ohne ZusammenfassungMit 4 Abbildungen     

Transition Metal-Free Aromatic C−H,C−N,C−S and C−O Borylation

Aromatic organoboron compounds are highly valuable building blocks in organic chemistry. They were mainly synthesized through aromatic C−H and C−Het borylation, in which transition metal-catalysis dominate. In the past decade, with increasing attention to sustainable chemistry, numerous transition metal-free C−H and C−Het borylation transformations have been developed and emerged as efficient methods towards the synthesis of aromatic organoboron compounds. This account mainly focuses on recent advances in transition metal-free aromatic C−H, C−N, C−S, and C−O borylation transformations and provides insights to where further developments are required.     

System BaRu1−xCoxO3−y

In the BaRu_1−xCo_xO_3−y. system between 600 and 1300°C (ruthenium rich) or 900°C (cobalt-rich side), different perovskite stacking polytypes are present in air: the pure ruthenium compound BaRuO₃ with the rhombohedral 9R structure (sequence, (hhc)₃); a ruthenium-rich (x = 0.1) and a cobalt-rich (x = 0.667−0.75) hexagonal 4H phase (sequence, (hc)₂); a phase with the hexagonal BaTiO₃ structure (6H; sequence, (hcc)₂; x = 0.25−0.667); a 5H phase (sequence, hhccc; x = 0.667-∮.95) and the pure cobalt polytypes BaCoO_3−y with 2H (sequence, (h)₂) and 12H structures (sequence, (hhhccc)₂). The phase relations and properties are reported.     

Secondary environment effects on the first step of the protonation of SO 4 2− in saline aqueous solutions

The solubility of strontium sulfate in the mixtures of isomolar LiClO₄(NaClO₄) and HClO₄ aqueous solutions was determined at 25°C and ionic strengths of I = 0.5, 1.0, 2.0, 3.0, and 4.0. At I>-2, the solubility of SrSO₄ as a function of the hydrogen ion (HClO₄) concentration passes through a maximum, clearly showing a substantial contribution from environment effects (H⁺ substitution for Li⁺ or Na⁺), which counteract complexation (i.e., HSO ₄ ^? formation). A correct method for separating these two effects was proposed, and the parameters of the environment effect and the standard values of pSP° and logβ° were evaluated.     

Hydrolysis of Methylphenyldiethoxysilane with Rare Earth Superacid Catalysts SO2− 4/TiO2/Ln3+

Abstract

An environmentally benign hydrolysis of methylphenyldiethoxysilane (MePhSi(OEt)₂) catalyzed by a rare earth superacid catalyst SO ^2? ₄ /TiO₂/Ln³⁺ has been investigated. The hydrolysis rates decrease in the order SO ^2? ₄ /TiO₂/Nd³⁺ > SO ^2? ₄ /TiO₂/Y³⁺ > SO ^2? ₄ /TiO₂/Sm³⁺ > SO ^2? ₄ /TiO₂. The hydrolysis of MePhSi(OEt)₂ is a first-order reaction with respect to the concentration of MePhSi(OEt)₂, and the hydrolysis rate constant increases with increasing temperature. The activation energy E _a and the pre-exponential factor for this hydrolysis catalyzed by SO ^2? ₄ /TiO₂/Nd³⁺ have been determined as 322.50 kJ mol^?1 and 7.12 × 10⁴¹ s^?1, respectively. The products of the hydrolysis are oligomers of polymethylphenylsiloxane. The mechanism of MePhSi(OEt)₂ hydrolysis is also discussed.     

Chromatography of Anions on Alumina Thin Layers: Effect of Transition Metals on CI−-Br−-I− and No− 2-NO− 3 Separations

Abstract

Chromatographic behaviour of eighteen anions on thin layers of alumina and alumina mixed with silica gel (1:1, 1:2 and 2:1) has been studied using mixed acidic organic solvent systems containing formic acid. Though the addition of silica gel to alumina enhances the mobility and clarity of detection of anions, but it causes the increased tailing for Fe(CN)^3- ₆, Cr0₄ ^2- and Cr₂O₄ ^2-. Formic acid is responsible for the differential migration of anions. All the anions remained at the starting line (R_F = 0) in pure organic solvents. Formic acid-Ketone systems gave better results compared to formic acid-alcohol systems. Development time increases with the increase of viscosity/mol. wt. of organic solvents. The mutual separation of C1, Br^?, Br^?, I^? and NO^? ₂ and NO^? ₃ were achieved on pure alumina using formic acid-acetone solvent systems. The effect of transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) on C1^?-Br^?-I^? and NO^? ₂-NO^? ₃ separations has been studied.