NH4VO3在NH4H2PO4-H2O和(NH4)3PO4-H2O体系中的溶解度

采用等温溶解法测定了偏钒酸铵(NH₄VO₃)在NH₄H₂PO₄-H₂O和(NH₄)₃PO₄-H₂O体系中T = 298.15-328.15 K时的溶解度以及溶液的密度和pH值。结果表明, NH₄VO₃的溶解度随着(NH₄)₃PO₄或NH₄H₂PO₄溶液浓度的增大,先降低后升高,这是由于同离子效应、化学反应平衡及离子活度的共同作用。比较T = 298.15K时, NH₄VO₃分别在NH₄H₂PO₄-H₂O、(NH₄)₂HPO₄-H₂O和(NH₄)₃PO₄-H₂O体系中溶解度,发现在相同的磷酸盐浓度下, NH₄VO₃的溶解度在NH₄H₂PO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在(NH₄)₂HPO₄-H₂O体系中最小。进一步地,在T = 298.15 K和磷酸盐浓度C = 0.5 mol·kg^-1时,结合pH值和反应溶度积常数K_SP等计算三个体系中的平均离子活度系数(γ_±),发现γ_±值在(NH₄)₂HPO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在NH₄H₂PO₄-H₂O体系中最小,与溶解度规律一致。     

[NH4][(CH3)2NH2]2[Ta(C2O4)4]·2H2O: the first (oxalato)tantalate(V) complex structurally characterized

Abstract  The compound [NH₄][(CH₃)₂NH₂]₂[Ta(C₂O₄)₄]·2H₂O has been synthesized and characterized by elemental and TG/DTA analyses, IR spectroscopy and by the single-crystal X-ray diffraction study. The structure comprises the [Ta(C₂O₄)₄]³⁻ anion, NH₄ ⁺ and [(CH₃)₂NH₂]⁺ cations and crystallization water molecules. The Ta atom is octacoordinated by oxygen atoms from four bidentate oxalate groups forming a coordination polyhedron close to the triangular dodecahedron. The charge-assisted hydrogen bonds from both cations connect the [Ta(C₂O₄)₄]³⁻ anions into a three-dimensional framework. Graphical Abstract  The synthesis and properties of [NH₄][(CH₃)₂NH₂]₂[Ta(C₂O₄)₄]·2H₂O, the first structurally characterized compound with the tetra(oxalato)tantalate(V) anion, is reported.      

Vibrational spectroscopy of synthetic stercorite H(NH4)Na(PO4)·4H2O--a comparison with the natural cave mineral

In order to mimic the chemical reactions in cave systems, the analogue of the mineral stercorite H(NH(4))Na(PO(4))·4H(2)O has been synthesised. X-ray diffraction of the stercorite analogue matches the stercorite reference pattern. A comparison is made with the vibrational spectra of synthetic stercorite analogue and the natural Cave mineral. The mineral in nature is formed by the reaction of bat guano chemicals on calcite substrates. A single Raman band at 920 cm(-1) (Cave) and 922 cm(-1) (synthesised) defines the presence of hydrogen phosphate in the mineral. In the synthetic stercorite analogue, additional bands are observed and are attributed to the dihydrogen and phosphate anions. The vibrational spectra of synthetic stercorite only partly match that of the natural stercorite. It is suggested that natural stercorite is more pure than that of synthesised stercorite. Antisymmetric stretching bands are observed in the infrared spectrum at 1052, 1097, 1135 and 1173 cm(-1). Raman spectroscopy shows the stercorite mineral is based upon the hydrogen phosphate anion and not the phosphate anion. Raman and infrared bands are found and assigned to PO(4)(3-), H(2)O, OH and NH stretching vibrations. Raman spectroscopy shows the synthetic analogue is similar to the natural mineral. A mechanism for the formation of stercorite is provided.     

Detection of a ferroelastic phase transition in Csx(NH4)1−xLiSO4 with the use of the DSC method

In this paper the technology of producing solid solutions of Cs_x(NH₄)_1?xLiSO₄ using the slow evaporation method is presented. Appropriate conditions were chosen to grow large samples. The ammonium ion content in the solid solutions was determined using the Kjeldahl method. It was found that the real ammonium ion concentration is twice lower than the one applied in the initial substances. At room temperature, the base crystal, lithium cesium sulfate (CsLiSO₄), is paraelastic, whereas lithium ammonium sulfate (NH₄LiSO₄) is ferroelectric. It is expected that as a result of substituting Cs⁺ ions with $ N{\text{H}}_{4}^{ + } $ N H 4 + ions, instead of the Cs⁺ ions, the modification of the ferroic properties of solid solutions of Cs_x(NH₄)_1?xLiSO₄ will take place. Tests conducted with the use of the differential scanning calorimetry method (DSC) allowed the detection of the ferroelastic phase transition which takes place in these compounds. A gradual increase of temperature transition was observed from 202 K for the pure CsLiSO₄ to 203.8 K for Cs_0.90(NH₄)_0.10LiSO₄ and 230.1 K for Cs_0.85(NH₄)_0.15LiSO₄ with the increase of $ N{\text{H}}_{4}^{ + } $ N H 4 + ions concentration. Using polarized light microscopy, a ferroelastic domain structure was detected in the examined solid solutions, which appeared below the structural phase transition temperature.     

Phase Equilibria in the System NH4Al(SO4)2–H2SO4–H2O

Equilibrium solubility curves of the ammonium aluminium sulphate in aqueous solutions of sulphuric acid have been calculated using checked literature data and our own measurements. The concentration of sulphuric acid ranged from 0 to 23 mass%, temperature range between 20 and 60°C has been extrapolated up to 75°C by means of a thermodynamically based correlation method. The solubility correlation as well as the hydration analysis implied a possible destructuralization of solutions at higher acid concentrations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,crystal structure of Gd(H2O)(C2O4)2 · NH4 and of La(C2O4)2 · NH4. Characterization of the Ln(H2O)(C2O4)2 · NH4 with Ln=Eu…Yb

Single crystals of two lanthanide complexes, presenting similar formula Ln(H₂O)_x(C₂O₄)₂ · NH₄ with Ln=La, x=0 and Ln=Gd, x=1, have been prepared, in closed system at 200 °C. The gadolinium complex is bi-dimensional. A layer is built by the packing of the basic unit, [Gd(C₂O₄)]₄. The gadolinium atoms are related only by bischelating oxalate ligands, the ammonium ion and the water molecule (bound to the gadolinium atom) are localized into the interlayer space. The lanthanum complex is tri-dimensional. The basic building unit remains approximately the same and the packing of these units form a layer. However, within these units, the lanthanum atoms are related by either an oxalate ligand or an edge. Moreover, an oxalate ligand assumes the connection between the layers. The ammonium ion is localized into two sets of intersecting channels. Pure phase of the gadolinium complex has been prepared at 100 °C and extended to some lanthanide elements, Eu…Yb. As the size of the lanthanide ionic radius is decreasing, it is noticeable that the a unit–cell constant follows an expansion pattern while the others two follow an usual contraction one. The thermal behavior of this family shows that the anhydrous compounds are obtained and that some water molecule is sorbed during the cooling. Thus, the anhydrous compounds present a relatively open-framework with some small micropores.     

(NH4)2SO4-NH4SCN-RhB-H2O体系浮选分离汞(Ⅱ)的研究

[Hg(SCN)4]^2-与罗丹明B阳离子(RhB^ )形成不溶于水的三元配合物(RhB)2[Hg(SCN)4]，在一定量(NH4)2SO4存在下，此三元配合物可浮于盐水相上形成界面清晰的两相，在两相形成过程中，Hg^2 被定量浮选，而Cd^2 、Cu^2 、Mn^2 、CO^2 、Ni^2 、Ee^2 、Al^3 等不被浮选，无需加入掩蔽剂就可实现Hg^2 与这些离子之间的定量分离。与其它体系相比，该体系无毒、无环境污染、分相速度快、相分离界面清晰、操作简便、成本低。     

Coupling of ν(NH⋯N) vibrations with the γ(NH⋯N) overtone in solid imidazole derivatives

The IR spectra of a number of imidazole derivatives were studied in the solid state at room and liquid nitrogen temperatures. The bands ascribed to stretching and out-of-plane deformation vibrations of NH groups involved in strong NH⋯N hydrogen bonds were analysed. The energy of this bond reflected in the position of the ν(NH⋯N) band changes over a broad range so that it was possible to investigate band shaping due to the overlap with the overtone band of the γ(NH⋯N) mode. The correlation between the γ(NH⋯N) and ν(NH⋯) frequencies shows that the γ(NH⋯N) value for strong NH⋯N bridges only slightly depends on ν(NH⋯N).     

Synthesis and Structure of [Pd(NH3)4][cis-Pd(NH3)2(SO3)2][Pd(NH3)3(SO3)] · H2O

A new palladium compound [Pd(NH₃)₄][cis-Pd(NH₃)₂(SO₃)₂][Pd(NH₃)₃(SO₃)] · H₂O (I) was synthesized and its structure was studied by X-ray powder diffraction method. In the course of the synthesis, the initial trans-diamminesulfite anionic complex is transformed into the cis-configuration. Further heating in aqueous solution results in isomerization of a substance into a neutral complex [Pd(NH₃)₃(SO₃)]. Crystals I are triclinic: a = 10.3297(2) Å, b = 14.1062(3) Å, c = 6.8531(1) Å, = 101.36(0)°, = 92.74(0)°, = 92.71(0)°, space group P1¯. Structure I consists of the columns with alternating cis-[Pd(NH₃)₂(SO₃)₂]^2– and [Pd(NH₃)₃(SO₃)] complexes and [Pd(NH₃)₄]²⁺ ions between the columns.     

Studies of the hydrated oxonium radical H3O·(H2O)n and the ammoniated ammonium radical NH4·(NH3)n by neutralized ion beam techniques

Neutralized ion beam studies of the clusters NH₄·(NH₃)_n and H₃O·(H₂O)_n,n = 0–3, and their fully deuterated analogs are presented. Stabilization of the hypervalent monomer radicals is found to accompany solvation. Cluster stability is found to decrease with increasing size. Reasons for this observation are discussed. Internally excited clusters are found to stabilize efficiently through the sequential loss of structural units (NH₃ or H₂O). The mixed isotopic dimer clusters (D₂¹⁸O)·D·(D₂¹⁶O) and (HDO)·D·(D₂O) are also investigated. Presence of the D₃¹⁶O radical structural unit is found to be crucial to dimer stability. This is consistent with the results of earlier investigations involving the monomer which showed the surprising lifetime progression τ(D₃¹⁶O) ≫; τ(D₃¹⁸O) ⩾ τ(H₃¹⁶O).     

(NH4)2SO4在TiO2表面上的行为研究

硫助金属氧化物(sulfate promoted metal oxides)是一类新型固体酸催化剂,可用于多种酸催化反应.用(NH_4)_2SO_4、SO_3、SO_2或H_2S 作为助剂,以Fe_2O_3、TiO_2和ZrO_2为底物均可制得硫助金属氧化物(SPMO).     

二维配位聚合物(NH3+CH2CH2NH3+)(NH2CH2CH2NH3+)2[(VO)4(PO4)4(H2O)2]·2H2O的水热合成及晶体结构

无机-有机杂化钒氧酸盐由于其结构的多样性以及在催化、医药、光、电、磁等材料领域中的应用前景而受到人们的广泛关注。近年来这一研究领域的重大进步是将有机氮配体或者过渡金属配合物直接连接到矾氧骨架上以获得各种新奇结构。合成出许多属于L/V/O、MXLY/V/O、L/P/V/O和MXLY     

Solubility and stability of (NH4)2SO4 · H2O2 in aqueous solutions and change in some crystallographic parameters of (NH4)2SO4 precipitates

Stability of (NH₄)₂SO₄ · H₂O₂ aqueous solutions and some structural changes in ammonium sulfate in the course of its solvation and subsequent desolvation were studied.     

A cobalt molybdenum phosphate with a tunnel: Hydrothermal synthesisand structure of (NH3CH2CH2NH3)4·(NH3CH2CH2NH2)·Na·[Co2Mo12O30(PO4)(HPO4)4(H2PO4)3]·5H2O

Transition Metal Chemistry -     

A theoretical investigation on the structures of (NH3)·(H2SO4)·(H2O)0-14 clusters

Ternary clusters (NH₃)·(H₂SO₄)·(H₂O)_n have been widely studied. However, the structures and binding energies of relatively larger cluster (n > 6) remain unclear, which hinders the study of other interesting properties. Ternary clusters of (NH₃)·(H₂SO₄)·(H₂O)_n, n = 0-14, were investigated using MD simulations and quantum chemical calculations. For n = 1, a proton was transferred from H₂SO₄ to NH₃. For n = 10, both protons of H₂SO₄ were transferred to NH₃ and H₂O, respectively. The NH₄⁺ and HSO₄⁻ formed a contact ion-pair [NH₄⁺-HSO₄⁻] for n = 1-6 and a solvent separated ion-pair [NH₄⁺-H₂O-HSO₄⁻] for n = 7-9. Therefore, we observed two obvious transitions from neutral to single protonation (from H₂SO₄ to NH₃) to double protonation (from H₂SO₄ to NH₃ and H₂O) with increasing n. In general, the structures with single protonation and solvated ion-pair were higher in entropy than those with double protonation and contact ion-pair of single protonation and were thus preferred at higher temperature. As a result, the inversion between single and double protonated clusters was postponed until n = 12 according to the average binding Gibbs free energy at the normal condition. These results can serve as a good start point for studies of the other properties of these clusters and as a model for the solvation of the [H₂SO₄-NH₃] complex in bulk water.     

三元体系NH4Cl-SbCl3-HOAc(25℃)的研究

本文测定了三元体系NH4Cl-SbCl3-HOAc在25℃时平衡态和介稳态的溶度及部分饱和溶液的折光指数, 并绘制了相应的溶度图. 体系在稳定平衡态时有五种固相: NH4Cl、SbCl3(原始盐), 5NH4Cl-SbCl3(1)、2NH4Cl-SbCl3.5HOAc(2)和5NH4Cl-3SbCl3.2.5HOAc(3)(复盐). 一支介稳溶度曲线所对应的固相是3NH4Cl.SbCl3(4). 本文初步描述了以上四种复盐的一些物理化学性质. 体系中合成的二元复盐1和溶剂合复盐2与3文献中均未见报道. 本文提供了一种制备3NH4Cl.SbCl3的新方法.     

Na2CrO4-(NH4)2CrO4-H2O体系的相图

铬盐工业是无机盐工业的一个主要分支,其主要产品有重铬酸钠、铬酸酐、铬酸铵、氧化铬等,广泛用于合金材料、电镀、制革、印染、橡胶等部门,是国民经济中重要的基础化工原料工业．铬盐生产系先将铬铁矿制成铬酸钠及重铬酸钠,然后再进一步加工制成其它铬盐产品．在铬盐...     

Na2CrO4-(NH4)2CrO4-H2O体系的相图

铬盐工业是无机盐工业的一个主要分支,其主要产品有重铬酸钠、铬酸酐、铬酸铵、氧化铬等,广泛用于合金材料、电镀、制革、印染、橡胶等部门,是国民经济中重要的基础化工原料工业.     

Crystal structure and single crystal EPR of (NH4)2(15-crown-5)3[Cu(mnt)2] and (NH4)2(benzo-15-crown-5)4[Cu(mnt)2]·0.5H2O

The X-ray crystal structures of (NH4)2(15-crown-5)3[Cu(mnt)2] (1) and (NH4)2(benzo-15-crown-5)4- [Cu(mnt)2]·0.5H2O (2) were determined. Two single crystals are composed of distinct structures of ammonium-crown ether supramolecular cation and [Cu(mnt)2]2- anion. The triple-decker dication in complex 1 and a sandwich dimmer in complex 2 were observed. X-Band EPR studies on the single crystals of both complex 1 and complex 2 have been carried out at room temperature, which revealed that complex 2 showed a perfect hyperfine structure of Cu whereas that of complex 1 could not be observed. The principal values and direction cosines of the principal axes of the g and A tensors were computed by a least-squares fitting procedure. The spin density of Cu(Ⅱ) was estimated according to the principal values of the A tensors and compared well with the results calculated based on DFT method.