Synthesis and Crystal Structure of Tetraamminelithium-Rubidiumtriselenide, Li(NH3)4RbSe3, and Pentaamminesodium-Rubidiumtriselenide-Ammonia(1/3), Na(NH3)5RbSe3 · 3NH3

Summary. The ammoniates Li(NH₃)₄RbSe₃ and Na(NH₃)₅RbSe₃·3NH₃ were prepared by the reduction of Rb₂Se₅ with lithium or sodium in liquid ammonia. Single crystals were isolated and characterized by X-ray structure analysis using low temperature techniques. Both compounds contain triselenide anions Se₃^2–, which coordinate to rubidium cations forming ¹[RbSe₃]^– or ¹[Rb(NH₃)₂Se₃]^– chains. The chains are separated in the crystal structures by the homoleptic ammine complexes Li(NH₃)₄⁺ and Na(NH₃)₅⁺.     

Near-saturation (P,ρ,T) and vapor-pressure measurements of NH3, and liquid-phase isothermal (P,ρ,T) and bubble-point-pressure measurements of NH3+H2O mixtures

Near-saturation pressure, density, and temperature (P,ρ,T) and vapor-pressure measurements for NH₃ are reported over a temperature range from 279 to 392 K. Liquid-phase isothermal (P,ρ,T) and bubble-point-pressure measurements for two standard mixtures of NH₃+H₂O (x_NH3=0.8360 and 0.9057 mole fraction) are reported over a temperature range from 280 to 379 K and at pressures to 7.7 MPa. These data are compared to literature data and correlations and agree within ±3% for bubble-point pressures, ±0.005 g/cm³ for liquid densities, and ±0.0011 g/cm³ for vapor densities. A consistent data set for equation-of-state optimization at high concentrations of NH₃ is proposed.     

Li,K∥F,NO3 and Li,K∥Cl,NO3 three-component reciprocal systems

Phase equilibria in Li,K∥F,NO₃ and Li,K∥Cl,NO₃ three-component reciprocal systems were studied by differential scanning calorimetry (DSC). Eutectic compositions (mol %) in the Li,K∥F,NO₃ system were determined to be as follows: 5.0 LiF, 10.0 KF, and 85.0 KNO₃ with T _m = 281°C and 48.5 KNO₃, 44.0 LiNO₃, and 7.5 LiF with T _m = 105°C. Eutectic compositions (mol %) in the Li,K∥Cl,NO₃ system were determined to be as follows: 10.0 LiCl, 32.1 KCl, and 57.9 LiNO₃ with T _m = 147°C and 44.5 KNO₃, 45.0 LiNO₃, and 10.5 KCl with T _m = 97°C.     

Kinetics and dynamics of the NH3 + H → NH2 + H2 reaction using transition state methods, quasi-classical trajectories, and quantum-mechanical scattering

On a recent analytical potential energy surface developed by two of the authors, an exhaustive kinetics study, using variational transition state theory with multidimensional tunneling effect, and dynamics study, using both quasi-classical trajectory and full-dimensional quantum scattering methods, was carried out to understand the reactivity of the NH(3) + H → NH(2) + H(2) gas-phase reaction. Initial state-selected time-dependent wave packet calculations using a full-dimensional model were performed, where the total reaction probabilities were calculated for the initial ground vibrational state and for four excited vibrational states of ammonia. Thermal rate constants were calculated for the temperature range 200-2000 K using the three methods and compared with available experimental data. We found that (a) the total reaction probabilities are very small, (b) the symmetric and asymmetric N-H stretch excitations enhance the reactivity, (c) the quantum-mechanical calculated thermal rate constants are about one order of magnitude smaller than the transition state theory results, which reproduce the experimental evidence, and (d) quasi-classical trajectory calculations, which were performed with the main goal of analyzing the influence of the zero-point energy problem on the final dynamics results, reproduce the quantum scattering calculations on the same surface.     

用NH4Cl氯化Li2CO3的研究

近年来利用熔盐电解法制备Al-Li合金已开始受到重视。但由于LiCl具有强烈的吸水性给工艺及其电解质溶液物化性质的研究带来很大的困难。因此本文利用热分析手段研究了NH_4Cl氯化Li_2CO_3的反应,为今后在电解工艺及其基础研究中用NH_4Cl定量氯化Li_2CO_3取代直接使用LiCl提供依据。     

Structural Properties and Thermal Behavior of Li2CO3–BaCO3 System by DTA,TG and XRD Measurements

The binary system Li₂CO₃–BaCO₃ was studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and X-ray phase analysis. The composition of carbonate and CO₂ partial pressure influence on the thermal behavior of carbonate were examined. It was shown that lithium carbonate does not form the substitutional solid solution with barium carbonate, however the possible formation of diluted interstitial solid solutions is discussed. Above the melting temperature the mass loss is observed on TG curves. This loss is the result of both decomposition of lithium carbonate and evaporation of lithium in Li₂CO₃–BaCO₃ system. Increase of CO₂ concentration in surrounding gas atmosphere leads to slower decomposition of lithium carbonate and to increase the melting point. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and Characterization of [NH3（CH2）2NH2（CH2）2NH3]BiCl6

1 INTRODUCTION During the past decade, a series of organic-inor- ganic hybrid compounds based on metal halide units have been prepared and studied[1]. The combination of organic and inorganic components at the mole- cular level affords us the opportunity to design new hybrid materials and modulate the properties of components[2]. As a result, some interesting proper- ties, such as non-linear optical[3], interesting magne- tic[4], efficient luminescence[2], ideal thermal and mechanical sta…     

Deprotonation of the peptide NH groups and diastereoselective hydrogenation of N-acetyl-α,-dehydrodipeptides

The peptide protons in N-acetyl-,-dehydrodipeptides (DHDP) dissociate in aqueous methanol in the presence of magnesium salts upon the addition of alkali, which favors the diastereoselectivities of their hydrogenation over Pd/C. By contrast, the N—H bonds of the N-acetyl groups in DHDP seem not to dissociate under these conditions. The dissociation of the peptide N—H bonds in strongly alkaline solutions was studied by ¹⁹F NMR spectroscopy for model compounds containing the 4-FC₆H₄ fragment.     

Identification and Characterization of Monomeric,Volatile SiCl3NH2 as Product of the Reaction between SiCl4 and NH3: An Important Intermediate on the Way to Silicon Nitride?

We studied the reaction of SiCl(4) with NH(3) by mass spectrometry and IR spectroscopy. By means of mass spectrometry, SiCl(3)NH(2) was for the first time identified as an intermediate generated in significant amounts in the course of the reaction. In additional experiments, SiCl(3)NH(2) was formed as a stable gaseous product of the ammonolysis of SiCl(4), and the product was identified and characterized in detail by IR spectroscopic methods (gas phase and matrix isolation) in combination with quantum-chemical calculations. The calculations also gave access to important thermodynamical data.     

The Cl−NH3, Cl−H2O,F−NH3 and F−H2O clusters and their photoelectron spectra

The geometries of the Cl^–NH₃, Cl^–H₂O, F^–NH₃ and F^–H₂O clusters are optimized using the coupled cluster method. The four lowest ionization potentials are then calculated, leading to the ground and low excited states of the neutral species. The first three IPs describe ionization from the externalp state of the halogen atom, whereas the fourth corresponds to ionization from the NH₃ or H₂O moiety, leading to charge transfer complexes. These complexes were recently observed in the photoelectron spectrum of Cl^–NH₃, in full accord with our calculations.Supported in part by the U.S.-Israel Binational Science Foundation     

Structure,stability and reactivity of inverse sandwich complexes M-Be3-M and M-Zn3-M (M = Li,Na, K,Cu, Ag,Au)

Quantum chemical calculations have b-een carried out on the inverse sandwich type complexes formed between coinage and alkali metals with Be₃ and Zn₃ rings. Calculations reveal that the complexes are stable toward dissociation. Their Lewis acidic character has been evaluated using fluoride ion affinity (FIA) calculation, which reveals their strong acidic character. Topological analysis of electron density has also been performed to investigate the nature of the bond between the metal and the fluoride ion. Calculations reveal non covalent nature in case of alkali series and covalent nature in case of coinage metal series.     

Solvothermal Synthesis and Characterization of （ NH3 CH2 CH2 NH3） HgSnS4 with a Column Structure

IntroductionSulfide-based open-framework materials are in-triguing compounds.They possess very diverse and in-teresting structures,and exhibit potential applicationsas a newgeneration of molecular sieves with the proper-ties of semiconductor materials[1].…     

Prokaryotic Expression, Purification, Antibody Production of a NH2 -Terminal Fragment of mCLCA3 Protein and Analysis of mClCA3 Protein Expression in Asthmatic Mouse Lung

mCLCA3 is a member of calcium activated chloride channel(CACC)family that may play an important role in mucin packaging and secretion in asthmatic and cystic fibrosis lung.To study the protein structure and expression of mCLCA3 in asthmatic mouse lung,an N-terminal 269 amino acid peptide of mCLCA3 was expressed in E.coli,purified to homogeneity and rabbit polyclonal antibodies against this peptide were generated.Immunohistochemistry of asthmatic mouse lung using the antibody indicated exclusive mCLCA3 expression in mucin granules of goblet cells in airway surface and lumen.Immunoblot analysis of lavage fluid from asthmatic mouse lung revealed a single 90 kDa protein form of mClCA3.The results demonstrate that the 90 kDa N-terminal peptide,neither the full-length protein nor the reported N-terminal 35 kDa cleaved form of mClCA3 is the major functional form involved in the packaging and exocytosis of mucin granules in asthmatic goblet cells.     

High-resolution observation and analysis of the I(2) (+) A(2)Π(3∕2,u)-X (2)Π(3∕2,g) system

Rotationally resolved absorption spectra of I(2) (+) were recorded in 12 065-13 062 cm(-1) region by employing optical heterodyne velocity modulation absorption spectroscopy. In total, 4054 lines were assigned to 24 bands in the A(2)Π(3∕2,u)-X(2)Π(3∕2,g) system spanning the vibrational levels υ(') = 1-4 and υ(n) (') = 11-19. The assigned lines were globally fitted and an error of 0.003 cm(-1) was obtained. Rotational constants, B(υ), were used to derive equilibrium parameters B(e) (') = 0.03977725(77) cm(-1), a(e) (') = 1.1819(24)×10(-4) cm(-1), r(e) (') = 2.584386(25) A? of the X(2)Π(3∕2,g) state, and B(e) (') = 0.0305787(37) cm(-1), a(e) (') = 1.2353(23)×10(-4) cm(-1), r(e) (') = 2.94758(18) A? of the A(2)Π(3∕2,u) state. Vibrational energies were used to derive ω(e) (') = 239.0397(55) cm(-1), ω(e)x(e) (') = 0.64951(87) cm(-1) of the X(2)Π(3∕2,g) state and ω(e) (') = 138.103(11) cm(-1), ω(e)x(e) (') = 0.45027(34) cm(-1) of the A(2)Π(3∕2,u) state. The A(2)Π(3∕2,u) (υ(n) = 13) state was found to be rotationally perturbed by the a(4)Σ(1/2,u) (-) (υ(n) = 17) state through second-order spin-orbit coupling.     

Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C

Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer) model has been used to calculate apparent molar volumes of H(2)SO(4) in 0-3 mol kg(-1) aqueous solutions of the pure acid and to represent directly the effect of the HSO(4)(-) ? H(+) + SO(4)(2-) reaction. The results are incorporated into the treatment of aqueous H(2)SO(4) density described here. Densities and apparent molar volumes from -20 to 50 °C, and from 0 to 100 wt % of solute, are tabulated for the electrolytes listed in the title and have also been incorporated into the extended aerosol inorganics model (E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) together with densities of the solid salts and hydrates.     

A synchrotron-based photoemission study of the MoO3∕Co interface

The electronic structures at the MoO(3)∕Co interface were investigated using synchrotron-based ultraviolet and x-ray photoelectron spectroscopy. It was found that interfacial chemical reactions lead to the reduction of Mo oxidation states and the formation of Co-O bonds. These interfacial chemical reactions also induce a large interface dipole, which significantly increases the work function of the cobalt substrate. In addition, two interface states located at 1.0 and 2.0 eV below the Fermi level are identified. These two states overlap at film thickness of between 2-4 nm, which suggests the MoO(3) intermediate layer may facilitate ohmic charge transport.     

Effect of BaNH,CaNH,Mg3N2 on the activity of Co in NH3 decomposition catalysis

Development of active and non-noble metal-based catalyst for H2 production via NH3 decomposition is crucial for the implementation of NH3 as a H2 carrier.Co-based catalysts have received increasing attention because of its high intrinsic activity and moderate cost.In this work,we examined the effect of BaNH,CaNH and Mg3 N2 on the catalytic activity of Co in the NH3 decomposition reaction.The H2 formation rate ranks the order as Co-BaNH>Co-CaNH>Co-Mg3 N2≈Co/CNTs within a reaction temperature range of 300-550℃.It is worth pointing out that the H2 formation rate of Co-BaNH at 500℃reaches20 mmolH2 gcat-1 min-1,which is comparable to those of the active Ru/Al2 O3(ca.17 mmolH2 gcat-1 min1)and Ru/AC(21 mmolH2 gcat-1 min-1)catalysts under the similar reaction conditions.In-depth research shows that Co-BaNH exhibits an obviously higher intrinsic activity and much lower Ea(46.2 kJ mol-1)than other Co-based catalysts,suggesting that BaNH may play a different role from CaNH,Mg3 N2 and CNTs during the catalytic process.Combined results of XRD,Ar-TPD and XAS show that a[Co-N-Ba]-like intermediate species is likely formed at the interface of Co metal and BaNH,which may lead to a more energy-efficient reaction pathway than that of neat Co metal for NH3 decomposition.     

Synthesis,Crystal Structure,and IR Investigations of [(NH3)5V?O?V(NH3)5]I4 · NH3 and [(NH3)5Ti?O?Ti(NH3)5]I4 · NH3

The reaction of VI₂ or TiI₃, respectively, with ammonia in the presence of traces of water or oxygen, respectively, leads to [(NH₃)₅M? O? M(NH₃)₅]I₄ · NH₃ with M = V, Ti. Their structures were solved by X-ray single crystal data: Pbca (No. 61), Z = 4, M = V: a = 12.482(4) Å, b = 14.819(6) Å, c = 13.286(5) Å, N(F ? 3σF) = 983, N(variables) = 88, R/R_w = 0.053/0.063, M = Ti: a = 12.628(4) Å, b = 14.970(4) Å, c = 13.359(3) Å, N(F ? 3σF) = 1188, N(variables) = 88, R/R_w = 0.043/0.047. The structures consist of corner sharing octahedra double units [(NH₃)₅M? O? M(NH₃)₅]⁴⁺ with eclipsed conformation which are stacked together according to the motif of a distorted cubic face centered arrangement for the bridging oxygen atoms. IR spectroscopic investigations of the undeuterated vanadium compound and of 5% deuterated samples hint to N? H … I hydrogen bridge bonds and to remarkable π-bonding between the transition metal and the bridging oxygen atoms.     

Effect of substituting6Li for7Li on ionic conductivity of α-Li3BO3

The ionic conductivity of γ-Li₃BO₃ is measured in wide intervals of temperatures and⁷Li to⁶Li ratios. It is found that the conductivity and activation energy vary nonmonotonically with variations in concentrations of the two isotopes; the concentration dependence of electroconductivity has a minimum, and that of the activation energy has a maximum at a⁷Li :⁶Li ratio of about 50 : 50 at. %; and the activation energy for conduction by⁶Li exceeds that by⁷Li