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1.
The curves of differential capacitance of the electrical double layer dense part in the Hg/(H2O + NaF + n-C4H9OH) are calculated by using the equations of the model of three parallel capacitors, with the corresponding adsorption parameters fitted. The curves of full differential capacitance in the system are calculated, basing on the obtained results combined with the classical theory of the diffuse layer, for the following concentrations of the supporting electrolyte: 0.003, 0.01, 0.03, 0.1, 0.3, and 1 M. By using the curves’ regression analysis it is shown that they agree very well with the model of two parallel capacitors, when six effective adsorption parameters are appropriately selected (provided the linear potential dependence of the effective attraction constant is allowed for). The dependences of all model’s effective parameters on the NaF concentration are found; they correspond well to the analogous experimental dependence in the system under study.  相似文献   

2.
The [M(1-MeIm)2(H2O)4](Tpht) · 4H2O complexes (where M = Ni, Co; 1-MeIm is 1-methylimidazole; H2Tpht is terephthalic acid) are synthesized and characterized by X-ray diffraction analysis. The ionic structure is built of the [M(1-MeIm)2(H2O)4]2+ cations and (Tpht)2? anions. The metal ions have a distorted octahedral coordination. The cations and anions are united by hydrogen bonding system.  相似文献   

3.
The crystal structures of isostructural mixed-ligand fluorosulfate complex compounds of indium(III) M2[InF3(SO4)H2O] (M = K, NH4), formed of K+ cations, NH4 + respectively, and complex [InF3(SO4)H2O]2– anions are determined. In the complex anion, the indium atom surrounded by three F atoms, the oxygen atom of the coordinated H2O molecule, and two oxygen atoms of the bridging sulfate group forms a slightly distorted octahedron (CN 6). Via alternating bridging SO4 groups, the polyhedra of In(III) atoms are arranged in polymer chains. The O–H???F hydrogen bonds organize the chains in a three-dimensional network. The K+ and NH4 + cations are located in the structure framework and additionally strengthen it.  相似文献   

4.
It is demonstrated by ESR measurements that O 2 (CO + O2) radical anions result from CO + O2 adsorption on the oxidized surface of CeO2. These radical anions are stabilized in the coordination sphere of Ce4+ cations located in isolated and associated anionic vacancies. This reaction shows an activation behavior determined by CO adsorption. The variation of O 2 (CO + O2) concentration with CO adsorption temperature suggests that surface carbonates and carboxylates participate in this reaction. In the (0.5– 10.0)%CeO2/ZrO2 system, O 2 forms on supported CeO2 and is stabilized on Ce4+ and Zr4+ cations. The stability of O 2 -Ce4+ complexes is lower on supported CeO2 than on unsupported CeO2, indicating a strong interaction between the cerium cations and the support.__________Translated from Kinetika i Kataliz, Vol. 46, No. 3, 2005, pp. 423–429.Original Russian Text Copyright © 2005 by Il’ichev, Kuli-zade, Korchak.  相似文献   

5.
The adsorption and electrokinetic characteristics of different titanium dioxide samples (produced by the Merck Co. and synthesized by the sol-gel method) are studied depending on the pH, background electrolyte concentration, and the nature of counterions (halide ions and Na+, K+, Ba2+, and La3+ metal ions). It is revealed that, in the presence of an indifferent electrolyte, the points of zero charge (PZC) for the synthesized TiO2 sample and the Merck sample correspond to pH = 6.0 ± 0.1 and 5.0, respectively. It is found that the nature of halide ions has almost no influence on the magnitude of the TiO2 surface charge σ0 (in the region of its positive values) and the position of PZC. An increase in the specificity of cations with a rise in the charge causes PZC shift to the acidic region and enhances the absolute values of σ0 at both negative and positive surface charges. It is established that the positions of PZC and isoelectric point in 10−2 M solutions of the examined 1: 1 electrolytes nearly coincide with one another. The ζ potential is found to decline in the following series of counterions: Cl, Br, and I due to an increase in the degree of filling of the dense part of the electrical double layer.  相似文献   

6.
The crystal and molecular structure of doubly protonated tetraazamacrocyclic complex of gold(III) [Au(C14H24N4)][H3O](ClO4)4 has been determined. The crystals are monoclinic: a = 11.158(2) Å, b = 8.243(1) Å, c = 14.756(2) Å; β = 98.65(1)°, V = 1341.8(3) Å3, Z = 2, ρ(calc) = 1.134 g/cm3, space group P21/n. The structure is built of almost flat centrosymmetrical Au(C14H24N4)]3+ and [H3O]+ cations and [ClO4]? anions. The gold atom is coordinated with four nitrogen atoms of the ligand forming a flat square. The coordinated ligand is protonated at its γ-carbon atoms of the two six-membered chelate rings. The Au-N bond lengths are almost identical (the mean value is 1.994 Å). The six-membered rings of the complex contain C=N diimine bonds. The [H3O]+ oxonium ion has H-bonds with the oxygen atoms of perchlorate ions.  相似文献   

7.
The complex [UO2(SeO4)(C5H12N2O)2(H2O)] (I) was synthesized and studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are orthorhombic: a = 13.1661(3) Å, b = 16.4420(5) Å, c = 17.4548(6) Å, Pbca, Z = 8, R = 0.0423. The structural units of crystal I are chains with the composition coinciding with that of the compounds of the AB2M 3 1 crystal chemical group of the uranyl complexes (A = UO 2 2+ , B2 = SeO 4 2? , M1 = C5H12N2O and H2O).  相似文献   

8.
Nano-structured spinel Li2Mn4O9 powder was prepared via a combustion method with hydrated lithium acetate (LiAc·2H2O), manganese acetate (MnAc2·4H2O), and oxalic acid (C2H2O4·2H2O) as raw materials, followed by calcination of the precursor at 300 °C. The sample was characterized by X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopy techniques. Electrochemical performance of the nano-Li2Mn4O9 material was studied using cyclic voltammetry, ac impedance, and galvanostatic charge/discharge methods in 2 mol L−1 LiNO3 aqueous electrolyte. The results indicated that the nano-Li2Mn4O9 material exhibited excellent electrochemical performance in terms of specific capacity, cycle life, and charge/discharge stability, as evidenced by the charge/discharge results. For example, specific capacitance of the single Li2Mn4O9 electrode reached 407 F g−1 at the scan rates of 5 mV s−1. The capacitor, which is composed of activated carbon negative electrode and Li2Mn4O9 positive electrode, also exhibits an excellent cycling performance in potential range of 0–1.6 V and keeps over 98% of the maximum capacitance even after 4,000 cycles.  相似文献   

9.
A new molybdophosphate (NH4)8{Mo2VO4[(Mo2VIO6)CH3C(O)(PO3)2]2}·14H2O (1), has been synthesized by the reaction of {Mo2VO4(H2O)6}2+ fragments with 1-hydroxyethylidenediphosphonate (hedp HOC(CH3)(PO3H2)2), and it is characterized by 31P NMR, IR, UV, element analysis, TG and single-crystal X-ray analysis. The structure analysis reveals that the polyoxoanion can be described as two {(Mo2VIO6)(CH3C(O)(PO3)2} units connected by a {Mo2VO4}2+ moiety. In the structure, the six Mo atoms are arranged into a new “W-shaped” structure, which represents a new kind of molybdophosphate.  相似文献   

10.
The A1, O, AlO, A12O, Al2O2, WO2, and WO3, partial pressures in the vapor over Al2O3 in a tungsten Knudsen effusion cell between 2300 and 2600 K were derived from A1+, O+, AlO+, A12O+, Al2O2+, WO2+, and WO3+, ion intensities. The mass spectrometer was calibrated against the equilibrium constant of the WO3(g) = WO2(g) + O(g) reaction. Refined values of the ionization cross sections of AlO and A12O2 were used in the partial pressure calculations. The enthalpies of atomization of aluminum suboxides were determined to be Δat H o(AlO, g, 0) = 510.7 ± 3.3 kJ mol−1, Δat H o(Al2O, g, 0) = 1067.2 ± 6.9 kJ mol−1, and Δat H o(Al2O2, g, 0) = 1556.7 ± 9.9 kJ mol−1.  相似文献   

11.
The crystal structures of three birefringent grossular-andradite natural garnets Ca3(Al,Fe)2(SiO4)3 were investigated using single-crystal X-ray diffraction data (MoKα, number of reflections measured 8065, 10619, 9213; R = 2.81, 2.74, 3.26%). According to the values of unit cell constants, inconsistent intensities of reflections and appearance of additional (forbidden) reflections explored garnets have different symmetry: cubic, sp. gr. (Fe/(Fe + Al) = 0.078, Δn = 0.0002); orthorhombic, sp. gr. Fddd (Fe/(Fe + Al) = 0.58, Δn = 0.0089); triclinic, sp. gr. or I1 and pseudo-orthorhombic (Fe/(Fe + Al) = 0.23, Δn = 0.0066). Careful refinement of all crystal structures in space groups , Fddd and has confirmed the symmetry reduction detected on the diffraction patterns and shown that dissymmetrization of cubic garnets connects with partial ordering of trivalent cations over Y-sites. Direct linear relationship between Fe-occupancy, an average Y–O bond lengths and octahedral O–O edges has been revealed. Cluster models of dissymmetrization have been regarded. Evidence for the “growth dissymmetrization” phenomena (kinetic phase transformations) as the reasons of the symmetry reduction of cubic garnets has been discussed. The reasonable assumption that the garnets crystal structures described as orthorhombic are triclinic, but the deviations from the orthorhombic symmetry so small, that cannot be manifested by of X-ray diffraction study has been taken.  相似文献   

12.
The U(VI) complex with cyanoacetic acid, [UO2(H2O)2(NCCH2COO)2] (I), was synthesized from an aqueous solution, and its X-ray diffraction analysis was carried out. The crystals are orthorhombic: space group Pca2 1, a = 25.9605(7) Å, b = 6.7634(2) Å, c = 6.3398(2) Å, V = 1113.15(6) Å3 at 100 K, and Z = 4. The coordination polyhedron of the uranium atom is a distorted pentagonal bipyramid. The cations UO 2 2+ are bound into infinite zigzag chains by the bridging carboxyl groups of one of the anions of cyanoacetic acid. The carboxyl oxygen atom of the second anion, which is not involved in coordination, and the nitrogen atoms of the cyano groups form hydrogen bonds with the coordination water molecules. The layer structure of the compound is formed through the hydrogen bonds. The absorption spectra in the visible and infrared ranges of the crystalline compound are measured and analyzed.  相似文献   

13.
Strontium barium niobate crystals with congruent melting composition Sr0.61Ba0.39Nb2O6 (SBN-61), both nominally pure and doped with Cr3+ и Ni3+ ions, have been investigated by neutron diffraction. Different strontium and barium contents as well as their different distribution over the Sr1, of Sr2 and Ba2 crystallographic sites of SBN-61 structure, caused by introduction of dopants, have been revealed. Coordination polyhedra of cations have been established based on the analysis of cation–anion internuclear distances together with the calculation of bond-valence sums for cations, which are equal to their formal charge. It was found that the Nb1 and Nb2 atoms are located in distorted octahedra with quadfurcated (the Nb1O6 polyhedron) or bifurcated (the Nb2O6 polyhedron) vertices, and the Sr1 atoms are located in a cuboctahedron with bifurcated vertices in the base plane. Different polyhedra have been revealed for the Sr2 and Ba2 atoms: Sr2 atoms are coordinated by 15 oxygen atoms to form a highly distorted five-capped pentagonal prism, whereas Ba2 atoms are located in a highly distorted three-capped trigonal prism with a coordination number 9. Comparison of interatomic and internuclear distances, determined by X-ray and neutron diffraction analyses, respectively, allowed to reveal a highly pronounced shift of electron density in Nb1 and Sr2 polyhedra, responsible for the covalent bond and properties of crystals. Location of Cr3+ и Ni3+ dopant ions in the SBN-61 structure as well as their formal charges has been discussed.  相似文献   

14.
A novel uranyl complex with dimeric lacunary polyoxoanion like open-mouthed clam, Na5[(A-α-SiW9O33H3)2K{UO2(H2O)}2], was prepared and characterized by elemental analysis, infrared and ultraviolet–visible spectroscopy and single crystal X-ray diffraction. In the anion, two A-α-SiW9O3410− groups share two terminal oxygen atoms Od′ derived from removal of three corner-shared W atoms from saturated α-Keggin anion, forming a dimeric anion with an open mouth in which potassium ion and uranyl ions are coordinated. Uranium atom adopts a pentagonal bipyramidal geometry. The coordinating anions are linked by sodium ions via coordination of terminal or bridging oxygen atoms, forming two-dimensional layer arrangement. Between the layers are the hydrogen bonds from which a supramolecular architecture is created. UV–VIS spectrum gives W–O and U–O charge transfer transitions at 230–265 and 432 nm, showing the change of geometry of the polyanion and weakening of the U–O bonds of the uranyl cation. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users.  相似文献   

15.
A supramolecular adduct of gadolinium aqua nitrato complex and cucurbit[6]uril { [Gd(NO3)(H2O)7](C5H5N)@(C36H36N24O12)}(NO3)2·10H2O is obtained by slow diffusion of methanol into an aqueous solution containing gadolinium nitrate, pyridine, and cucurbit[6]uril. According to single crystal X-ray diffraction data, water molecules coordinated to metal atom make hydrogen bonds to polarized carbonyl groups of the macrocycle. The heptaaquanitratogadolinium(III) [Gd(NO3)(H2O)7]2+ cation is structurally characterized for the first time. Crystal system is triclinic, space group \(P\overline 1 \), a = 12.3137(4) Å, b = 14.2334(5) Å, c = 19.5629(6) Å; α = 80.850(1)°, β = 86.879(1)°, γ = 68.855(1)°; V = 3157.15(18) Å3, Z = 2. Oriented hydrogen-bonded chains of alternating cucurbit[6]uril molecules and gadolinium aqua cations form in the crystal structure.  相似文献   

16.
A new organic-inorganic hybrid material (C13H28N2)2[Cr2O7][Cr3O10]·H2O (1) was synthesized by slow solvent evaporation at room temperature, and its crystal structure was determined by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group P21/c. The asymmetric unit contains two crystallographically independent 1,3-bis(4-piperidinium)propane, (H2bppp)2+ cations (A and B), one trichromate Cr3O 10 2? anion, one dichromate Cr2O 7 2? anion, and one water molecule. All these entities are interconnected into a complicated two-dimensional hydrogen bonded network via N–H?O and O–H?O hydrogen bonds. Furthermore, this structure is stabilized by a large number of C–H?O interactions, thus establishing a three-dimensional network structure. This compound appears to be the first example of chromates containing both Cr2O7 and Cr3O10 groups.  相似文献   

17.
Two new coordination polymers, (EMIM)2[M(Pydc)2] (M is Co, Zn; EMIM is 1-ethyl-3-methylimidazolium; H2Pydc is 2,5-pyridinedicarboxylic acid), have been synthesized through the reaction of cobalt or zinc nitrate with H2Pydc in the ionic liquid medium. The structures exhibit a two-dimensional 4.4-network with the imidazolium cations, acting as charge compensating agent, located between the layers of the coordination anion polymeric frameworks. The article is published in the original.  相似文献   

18.
The reaction of a sulfur and oxygen-bridged 8-quinolinolato trinuclear molybdenum cluster [Mo3OS3(qn)3(H2O)3]+ (3; Hqn = 8-quinolinol) with equimolar amounts of acetylene carboxylic acid, 4-pentynoic acid, 5-hexynoic acid, acetic acid, and pimelic acid gave clusters having μ-carboxylato groups, [Mo3OS3(qn)3(H2O)(μ-HC≡CCOO)] (6), [Mo3OS3(qn)3(H2O)(μ-HC≡C(CH2)2COO)] (7), [Mo3OS3(qn)3(H2O)(μ-HC≡C(CH2)3COO)] (8), [Mo3OS3(qn)3(H2O)(μ-CH3COO)] (4), and [{Mo3OS3(qn)3(C2H5OH)}2(μ-C7H10O4)] (5), respectively. X-ray structural analyses, 1H NMR, and electronic spectra of these clusters made clear that each of the COO groups of the reagents bridges two Mo atoms in each cluster and that no adduct formation occurred at the sulfurs in the clusters. The reaction of 3 with a large excess-molar amount (50 times) of acetylene carboxylic acid gave [Mo3OS(μ3-SCH=C(COOH)S)(qn)3(H2O)(μ-HC≡CCOO)] (9) with two molecules of acetylene carboxylic acid, one acting as a carboxylato bridge and the other in adduct formation, as supported by the electronic and 1H NMR spectra. The corresponding aqua cluster [Mo3OS3(H2O)9]4+ (1), on the contrary, reacts with acetylene carboxylic acid to give adduct [Mo3OS(μ3-SCH=C(COOH)S)(H2O)9]4+ (2). Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

19.
The crystal structure of Na3NpO2(OOCCH3)3ClO4 · H2O was studied by single-crystal X-ray diffraction method. The structure is composed of the complex anions NpO2(OOCCH3)3]2−, perchlorate anions, Na cations, and water molecules. The oxygen environment of Np(V) is a hexagonal bipyramid whose equatorial plane is formed by the oxygen atoms of three acetate ions. In addition to the acetate anions, the structure contains the perchlorate ion whose oxygen atoms, except for one, are included in the coordination environment of Na+ cations.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 636–640.Original Russian Text Copyright © 2005 by Charushnikova, Fedoseev, Starikova.  相似文献   

20.
The time curves of full polarization resistance of Ni cermet electrode modified with CeO2 − δ additive were studied by means of impedance spectroscopy in binary gas mixtures x% H2 + (100 − x)% H2O, 10% CO + 90% CO2 and multicomponent gas mixtures H2 + CO2 + H2O + CO + Ar of various composition at the temperature of 900°C. The Ni cermet electrode degradation rate in binary gas mixtures H2 + H2O was shown to increase sharply at the partial water pressure over 45%. The Ni cermet electrode degradation rate in the mixture of 10% CO + 90% CO2 was significantly lower than that in 10% H2 + 90% H2O. The major changes in the electrode characteristics upon long exposure in working conditions were accounted for by changes in the high-frequency partial polarization resistance. In the course of long testing, the electrode microstructure was not significantly changed. In the presence of hydrogen-containing components (H2 and H2O), the carbon-containing components (CO and CO2) were shown to make an insignificant contribution to the current generation processes in Ni cermet electrode. It was suggested that strong degradation of Ni cermet electrode was caused by poisoning its reaction sites with strongly linked adsorption forms of water (hydroxyls) at the positive charge of electrode.  相似文献   

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