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1.
Direct hydrocarbon type solid oxide fuel cells are attractive from simple gas feed process and also high energy conversion efficiency. In this study, La0.5Sr0.5MnO3 (LSM55) perovskite oxide was studied as oxide anode for direct hydrocarbon type solid oxide fuel cell (SOFC). Although reasonable power density like 1 W/cm2 and open circuit voltage (OCV) (1.1 V) at 1273 K was exhibited when H2 was used as fuel, the power density as well as OCV of the cell using LSM55 for anode was significantly decreased when dry C3H8 was used for fuel. After power generation measurement, LSM55 phase was decomposed to MnO and La2MnO4. Effects of various dopants to Mn site in LSM55 were studied and it was found that partial substitution of Mn in LSM55 with other cation, especially transition metal, is effective for increasing maximum power density. In particular, reasonable high power density can be achieved on the cell using Ni-doped LSM55 for anode. On the other hand, Al substitution is effective for increasing stability against reduction and so, dopant effects of Al were studied in more details for dry C3H8 fuel. The power density as well as OCV increased with increasing Al content and the highest power density was achieved at x = 0.4 in La0.5Sr0.5Mn1 ? x Al x O3. Among the examined composition, it was found that the cell using La0.5Sr0.5Mn0.6Al0.4O3 anode shows the largest power density (0.2 W/cm2) at 1173 K and high OCV (1.01 V) against dry C3H8 fuel.  相似文献   

2.
The geometrical parameters of molecular structures of three types of aluminum–iron clusters containing in total four, five, and six Al and Fe atoms in structural units have been calculated by the OPBE/TZVP density functional theory (DFT) method with the Gaussian09 program package. It has been found that the AlFe3, Al2Fe3, and Al2Fe4 clusters can have four, eight, and nine structural modifications, which significantly differ in stability and geometric parameters. Bond lengths and bond and torsion (dihedral) angles are reported for each of these modifications.  相似文献   

3.
Measurement of the 3Π-3Π transition of C6H+ in the gas phase near 19486 cm−1 is reported. The experiment was carried out with a supersonic slit-jet expansion discharge using cavity ringdown absorption spectroscopy. Partly resolved P lines and observation of band heads permitted a rotational contour fit. Spectroscopic constants in the ground and excited-state were determined. The density of ions being sampled is merely 2×108 cm−3. Broadening of the spectral lines indicates the excited-state lifetime to be ≈100 ps. The electronic transition of HC6H2+ at 26402 cm−1 assumed to be 1A1-X1A1 in C2v symmetry could not be rotationally resolved.  相似文献   

4.
Arsenic 4-methoxy-8-mercaptoquinolinate As[C9H5(4-OCH3)NS]3 (I) was synthesized and studied by X-ray diffraction. Crystals are trigonal: space group R3, a = b = 13.9867(4) Å, c = 12.4991(5) Å, γ = 120°, V = 2117.58(12) Å3, ρ = 1.519 g/cm3, Z = 3. An arsenic atom in the crystal structure occupies a special position on axis 3. The structural unit of the crystal (neutral complex I) has symmetry C3. 4-Methoxy-8-mercaptoquinoline acts as a bidentate (N,S-) ligand. The coordination polyhedron of the arsenic atom is a symmetric octahedron (3S + 3N) or, with allowance for the lone electron pair, ψ-one-capped octahedron (3S + 3N + E). Bond lengths are as follows: As-S, 2.3179(7)Å; As…N 2.688(3) Å. The geometries of coordination polyhedra of arsenic atoms are compared in the crystal structures of As(C9H6NS)3, As[C9H5(2-CH3)NS]3, and As[C9H5(4-CH3)NS]3.  相似文献   

5.
We present an 27Al NMR study of the metal cluster compound Al50Cp*12 which is composed of (identical) Al50 clusters, each surrounded by a Cp* ligand shell, and arranged in a crystalline 3D array (here Cp* = pentamethylcyclopentadienyl = C5(CH3)5). The compound is found to be non-conducting, the nuclear spin-lattice relaxation in the temperature range 100–300 K being predominantly due to reorientational motions of the Cp* rings. These lead to a pronounced maximum in the relaxation rate at T ∼ 170 K, corresponding to an activation energy of about 850 K. Data for the related compound Al4Cp*4, containing very much smaller Al4 clusters are also presented. A comparison is drawn with the quadrupolar relaxation recently observed for the non-conducting fraction of Ga84 molecules in the metal cluster compound Ga84[N(SiMe3)2]20-Li6Br2(thf)20·2toluene. It is our pleasure to dedicate this paper to our colleague professor Günter Schmid at the occasion of his 70th birthday.  相似文献   

6.
A complex of uranyl perchlorate with imidazolidine-2-one as the molecular ligand, [UO2(Imon)4(H2O)](ClO4)2 (I), was synthesized and structurally characterized by X-ray diffraction analysis. The coordination number of the uranium atom is 7. The nearest environment of the uranyl ion includes four O atoms of the imidazolidine-2-one molecules and one O atom of the water molecule. The perchlorate anions are outer-sphere ligands. The crystals are monoclinic: space group P21/c; a = 16.294(3) Å, b = 16.135(3) Å, c = 9.987(2) Å, = 97.69 (3)°, V = 2603.0 (9) Å3, (calcd) = 2.117 g/cm3, Z = 4. The IR and luminescence spectra of the complex were recorded.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 919–924.Original Russian Text Copyright © 2004 by Andreev, Antipin, Budantseva, Tuchina, Serezhkina, Fedoseev, Yusov.  相似文献   

7.
More than twenty M6Al38 isomers and several M12Al32 isomers of carbon- and silicon-substituted aluminum clusters with six and twelve dopant atoms of general formula MnAl44–n(M = C and Si, n = 6 and 12) have been studied by the density functional theory method. Calculations predict that, in the lowest-lying M6Al38, isomer, all substitutions of C atoms for Al are localized in one outer surface layer of the aluminum cage. In the course of optimization, the C atoms with a negative charge of about 1e are incorporated into positions of the intermediate layer to transform it into a 12-atom face composed of three adjacent vertex-sharing six-membered rings with short C–Al bonds. In the favorable isomer of M6Al38, the dopants are scattered as individual Si atoms located in both outer layers or in the subsurface space between the outer layers and the inner core of the cluster. Optimization of low-lying isomers with twelve starting substitutions of C and Si for Al in both outer layers has localized two preferable C12Al32 isomers. One of them contains three covalently bonded diatomic C2 anions, which are combined through bridging aluminum atoms in the three-dimensional [C6Al7] cluster inside the severely distorted outer cage. In the second, most favorable, isomer, the dopants are distributed as isolated C anions; together with the bridging Al atoms, they form the [M12Al32] inner cage with an unusual dumbbell-like structure. For M12Al32, the aluminum cage undergoes moderate distortions. The silicon atoms remain in the outer layers and form five-membered ring subclusters [Si5] and [Si2Al3] bound to the neighboring intermediate layers through elongated and weakened Si–Al bonds. Evaluation of the energies of the model exchange reactions Al44 + M6 → M6Al38 + Al6 and Al44 + 2M6 → M12Al32 + 2Al6 shows that for M= C both reaction are exothermic, whereas for M = Si the former reaction is nearly isothermal and the second reaction is endothermic and requires significant energy inputs. The differences between the equilibrium structures and the relative positions on the energy scale of the isomers of the C6Al38–Si6Al38 and C12Al38–Si12Al38 clusters are examined.  相似文献   

8.
(U)PBE0/cc-pVDZ method is used to study the structure of C60Cl30, C60(OH)30 molecules and Fe@C60(OH)30 endocomplex. The triplet state of the endocomplex is shown to be the lowest in energy among its four states corresponding to different spin multiplicities and positions of Fe nucleus within the fullerene cavity. This state is characterized by bonding between the iron atom and one of two benzenoid cycles of the carbon cage, six internuclear Fe–C distances (208 pm), and 1s22s22p63s23p63d7.24s0.14p0.3 electron configuration of iron with spin population of 2.36.  相似文献   

9.
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   

10.
The electronic structure of the (η2-C60)Pd[P(Ph2)C5H4]2Fe complex was calculated by the “hybrid” B3LYP method. Comparison of the experimental X-ray emission C-Kα spectrum and theoretical spectrum of the compound demonstrated that the electron interactions between the C60 core, palladium atom, and organometallic fragment are described correctly in the framework of the quantum chemical method used. The electronic structure of the organometallic fullerene complex can be presented as a set of blocks of orbitals corresponding to different types of chemical bond. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2640–2644, December, 2005.  相似文献   

11.
Bismuth 2-methyl-8-quinolineselenolate, Bi[C9H5(CH3)NSe]3, was synthesized. X-ray analysis was used to determine the structure of this complex. The crystal chemistry of bismuth(III), antimony(III), and arsenic(III) 2-methyl-8-quinolineselenolates and 2-methyl-8-quinolinethiolates was discussed relative to the effect of going from Se to S as the ligand atoms and presence of a methyl group at C-2 of the quinoline system and unshared electron pair of the central atom in the complex.  相似文献   

12.
More than 20 М6Al38 isomers and several М12Al32 isomers for nitrogen- and phosphorus-substituted clusters with six and twelve dopant atoms M = N and P substituted for Al atoms in different positions at the surface of the aluminum cage and inside it have been studied by the density functional theory method. In the preferred N6Al38 isomer, all N atoms are substituted for Al atoms initially located in one outer layer of the cluster. In the course of geometry optimization, the nitrogen atoms are incorporated into positions in the neighboring intermediate layer, thus converting it into a 12-atom face consisting of three vertex-sharing adjacent six-membered rings with short N–Al bonds. For Р6Al38, a distribution of the dopant either in both surface layers or in the intermediate space between the surface layers and the inner core of the cluster is preferred. Optimization of alternative structures of the N12Al32 cluster with N atoms substituted for Al atoms in both outer layers is evidence in favor of the isomer in which the dopants are dispersed as separated monatomic anions N–. Together with their bridging Al atoms, these anions form the inner [N12Al14] cage with an unusual dumbbell-like structure in which the upper and lower halves are linked through N–Al bonds with the equatorial aluminum atoms. In the next low-lying isomer being ~23 kcal/mol higher on the energy scale, there is observed the “microclustering” of the dopant to form three covalently bonded diatomic dianions N22-; the latter, together with the bridging Al atoms are combined into a [N6Al6] “subcluster” inside the severely distorted outer cage. In P12Al32, the aluminum cage is subjected only to moderate distortions: the phosphorus atoms remain in the outer layers and form two three-membered rings [Р3]. The estimated energies of the model substitution reactions Al44 + M6 → M6Al38 + Al6 (1) and Al44 + 2M6 → M12Al38 + 2Al6 (2) demonstrate that all these reactions are exothermic; however, for the nitrogen-containing clusters, the decrease in energy with increasing number of substitutions increases from 66 (1) to 113 (2) kcal/mol, while in the case of phosphorus, it decreases from 45 (1) to 4 (2) kcal/mol. The results obtained for N6Al38, N12Al32, Р6Al38, and Р12Al32 are compared with the previous calculations for the C6Al38, C12Al32, Si6Al38, and Si12Al32 clusters.  相似文献   

13.
Chemical preparation, crystal structure, and NMR spectroscopy of a new trans-2,5-dimethylpiperazinium monophosphate are given. This new compound crystallizes in the triclinic system, with the space group P-1 and the following parameters: a = 6.5033(3), b = 7.6942(4), c = 8.1473(5) Å, α = 114.997(3), β = 92.341(3), γ = 113.136(3), V = 329.14(3) Å3, Z = 1, and Dx = 1.565 g cm?3. The crystal structure has been determined and refined to R = 0.030 and R w(F 2) = 0.032 using 1558 independent reflections. The structure can be described as infinite [H2PO4] n n? chains with (C6H16N2)2+ organic cations anchored between adjacent polyanions to form columns of anions and cations running along the b axis. This compound has also been investigated by IR, thermal, and solid-state, 13C and 31P MAS NMR spectroscopies and Ab initio calculations.  相似文献   

14.
The potential energy surfaces (PESs) of the model reactions Fe(P)O(NX2) + CH4 → Fe(P)(NX2) + CH3OH (X = H, F, Li) in the isolated state with different multiplicity have been calculated by the density functional theory B3LYP method with the 6-31G and 6-31G* basis sets. The optimized geometric, energetic, and spectroscopic characteristics of the key structures corresponding to local minima and transition states on the PES are determined; the energies and potential barriers of the reactions have been estimated, and their behavior as a function of the gas-phase states multiplicity and the electronegativity of the substituent X in the axial amino group has been studied. For all reactions, the lowest barriers are observed for the closely spaced quartet and doublet terms. The barriers considerably increase when the H atoms in the amino group are replaced by more electronegative atoms (F) and slightly decrease when H is replaced by more electropositive atoms (Li). On the basis of calculations for some structures corresponding to the stationary points on the PES of an analogous reaction of methane oxidation with the binuclear μ-N complex Fe(P)Fe(P)O, it was assumed that the effect of the second porphyrin ring on the upper active site in the binuclear μ-N complex is not too different from the effect of the amino group in the mononuclear complex Fe(P)O(NH2) and that the role of the second ring in the μ-N complex is mainly reduced to the steric protection of the nitrogen atom from the interaction with the oxidant.  相似文献   

15.
The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH2NHC(O)NH2)2](NO3)2 has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) Å3, space group P21/c, Z = 2, d msd = 2.136 g/cm3, μ(MoK α) = 2.143 mm−1. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R 1 = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied by the O atoms of the NO 3 outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO 3 anions are linked into a framework by N-H...O type hydrogen bonds. Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007.  相似文献   

16.
The search for stable structures of neutral Fe2C3 particle was based on the geometry optimization of the known FeC3 and Fe2C2 isomers with the Fe and C atoms approaching from various directions. The geometry optimization of more than 2,000 initial structures was carried out using the DFT based DMol3 method and converged to 41 stable configurations. The structures containing C3 triangle and the cyclic planar isomer with transannular bonds are found to have the lowest binding energies. The effective charges and total spin densities on the atoms were calculated using integral scheme incorporated in DVM and Hirshfeld procedure of DMol3. The relations between geometrical structures and spin moments ordering are discussed. For the evaluation of potential barriers the geometry optimization of all Fe2C3 configurations was performed with a thermal occupation, corresponding to the various values of the excitation energy.  相似文献   

17.
The ethylenediaminetetraacetate complex Li(H2O)3[Ga(Edta)] was synthesized and its crystal structure composed of octahedral (Ga(Edta) anions connected to the Li(H2O)3+ ion through the oxygen atom was studied. Five of the six hydrogen atoms of water molecules are involved in weak hydrogen bonds with the oxygen atoms of four Ga(Edta) complexes, the complex anion is hydrogen-bonded to five water molecules. In addition, shortened contacts C(221)–H(22A)…O(112) between the Ga(Edta) anions were found. As a result, the molecular packing in the crystal is determined by the three-dimensional lace of hydrogen bonds. The results are compared with published data for the lithium salts of Bi(III), Sb(III), Fe(III), Ni(II), and Hg(II) ethylenediaminetetraacetates.  相似文献   

18.
The complexes [Fe(DfgH)2(3-CONH2-Py)2] (I) and [Fe(DfgH)2(4-COOC2H5-Py)2] (II), where DfgH2 is α-benzyl dioxime, were obtained and examined by X-ray diffraction analysis. The equatorial planes of the coordination octahedra of the metal ions consist of two monodeprotonated α-benzyl dioxime residues united through intramolecular hydrogen bonds O-H…O into a pseudomacrocyclic system. The neutral molecules 3-CONH2-Py and 4-COOC2H5-Py are coordinated to the Fe2+ ion through the N atom of the heterocycle. Structure I is layered and structure II is molecular. Intermolecular interactions N-H…O are responsible for the formation of layers in crystal structure I.  相似文献   

19.
The structure of aluminum(III) tris-dipivaloylmethanate (Bruker Nonius X8 Apex diffractometer with a 4K CCD detector, λMoK α, graphite monochromator, T = 150(2) K) is determined, and the synthetic procedure for its preparation is suggested. Crystal data are: C2/c space group, a = 28.1587(12) Å, b = 18.5170(7) Å, c = 21.5332(8) Å, β = 97.573(1)°, V = 11129.8(8) Å3, Z = 12, d x = 1.033 g/cm3, R = 6.93. The complex has a molecular structure; the aluminum atom is octahedrally surrounded by six oxygen atoms of three chelating ligands; Al-O distances are 1.860(2)–1.873(2)0A; O-Al-O angles fall within 88.08(9)–91.96(10)° and 177.93(9)–179.83(14)°. The known crystal packings of metal tris-dipivaloylmethanates are analyzed. Three types of the arrangement of the molecules in the crystals denoted as α, β, and γ are identified.  相似文献   

20.
The quantum-chemical calculations of the (C6H5)2PCl3 molecule were performed by the methods RHF/6-31G(d) and MP2/6-31G(d) with complete and partial optimization of its geometry. The results of calculations were used for evaluating the NQR frequencies of 35Cl and the parameters of asymmetry of the of electric field gradient on the 35Cl nuclei of this molecule. According to the results of calculations with the partial optimization of geometry and to the experimental data of 35Cl NQR the bond lengths were found of central atom P in the solid state of this compound. The mutual influence of its axial and equatorial bonds was studied. It is shown that in chlorophosphoranes the 35Cl NQR frequencies of the axial and equatorial chlorine atoms decrease with the decrease in the bond lengths of phosphorus atom.  相似文献   

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