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1.
Matthias Weil Franz Werner Frank Kubel 《Monatshefte für Chemie / Chemical Monthly》2002,133(3):267-275
Summary. Single crystals of MgAl2F8(H2O)2 have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF3 and MgAlF5(H2O)2 in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F
2 > 2σ (F
2)) = 0.0282, wR(F
2 all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting
the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF6 octahedra with an overall composition of AlF4
− which are connected via common fluorine atoms of [MgF4/2(H2O)2/1] octahedra. Group-subgroup relations of MgAl2F8(H2O)2 to WO3(H2O)0.33 and to other M(II)M(III)2 F8(H2O)2 structures are briefly discussed. Above 570°C, MgAl2F8(H2O)2 decomposes under elimination of water into α-AlF3, β-AlF3, and MgF2.
Received October 29, 2001. Accepted (revised) December 6, 2001 相似文献
2.
M. G. Zuev 《Russian Journal of Inorganic Chemistry》2010,55(1):93-95
Solid-phase interactions in the V2O5-Ta2O5-MoO3 system were studied. The formation of com- pounds TaVO5 and VTa9O25 in the V2O5-Ta2O5 binary system was verified. Tetragonal VTa9O25-base solid solutions of the general formula Ta5 + 4x
V5 − 4x
O25 (x = 0.25–1) and TaVO5-base solid solutions of the general formula Ta
x
Mo1 − x
V2 − x
O8 − 3x
(x = 0.625–1) were found to form. Subsolidus phase equilibria in the V2O5-Ta2O5-MoO3 were determined. 相似文献
3.
Summary. The gadolinium–rhodium–indide Gd3Rh1.940(7)In4 was prepared by arc-melting of the elements and subsequent annealing in a corundum crucible in a sealed silica tube. Gd3Rh1.940(7)In4 adopts the hexagonal Lu3Co1.87In4 type, space group
, a = 781.4(5), c = 383.8(3) pm, wR2 = 0.0285, BASF = 0.375(1) (merohedric twinning via a twofold axis (xx0)), 648 F2 values, 22 variables. The structure is derived from the well known ZrNiAl type through an ordering of rhodium and indium
atoms on the Ni2 sites. The Rh/In ordering forces a reduction of the space group symmetry from
to
, leading to merohedric twinning for the investigated crystal. The Rh1 site has an occupancy of only 94.0(7)%. The investigated
crystal had a composition Gd3Rh1.940(7)In4. The main geometrical motif are three types of centered, tricapped trigonal prisms, i.e., [Rh1In26Gd3], [Rh2Gd6In23], and [In1Gd6In23]. The shortest interatomic distances occur for Rh–In (276–296 pm) followed by In–In (297 pm). Together, the rhodium and indium
atoms build up a three-dimensional [Rh1.940(7)In4] network, in which the gadolinium atoms fill slightly distorted pentagonal channels. The crystal chemistry of Gd3Rh1.940(7)In4 is discussed on the basis of a group-subgroup scheme. 相似文献
4.
Marcela Stoia C. Caizer M. Stefanescu P. Barvinschi I. Julean 《Journal of Thermal Analysis and Calorimetry》2007,88(1):193-200
This article presents the results
of our investigation on the obtaining of Ni0.65Zn0.35Fe2O4 ferrite nanoparticles embedded in a SiO2 matrix using
a modified sol–gel synthesis method, starting from tetraethylorthosilicate
(TEOS), metal (FeIII,NiII,ZnII)
nitrates and ethylene glycol (EG). This method consists in the formation of
carboxylate type complexes, inside the silica matrix, used as forerunners
for the ferrite/silica nanocomposites. We prepared gels with different compositions,
in order to obtain, through a suitable thermal treatment, the nanocomposites
(Ni0.65Zn0.35Fe2O4)x–(SiO2)100–x (where x=10,
20, 30, 40, 50, 60 mass%). The synthesized gels were studied by differential
thermal analysis (DTA), thermogravimetry (TG) and FTIR spectroscopy.
The formation of Ni–Zn ferrite in the silica matrix and the behavior
in an external magnetic field were studied by X-ray diffraction (XRD) and
quasi-static magnetic measurements (50 Hz). 相似文献
5.
To test the feasibility of local spin theory of Davidson and Clark for ferrodoxin clusters, the models [Fe2S2(SR)4]2− (R=—H, —CH3) are chosen for evaluation. This purpose is realized by calculating the local spin expectation values 〈S
A·S
B〉, 〈S
A
2
〉, and m
A and discussing the connection between these expected values and the Heisenberg spin model (HSM) and the Noodleman broken-symmetry
approach. In practical calculation, the spin-unrestricted Hartree-Fock (UHF) and spin-polarized density functional theory
(DFT) are used and the calculational qualities of these two methods are also discussed. In addition, the theoretical magnetic
coupling constants J
AB of these models are calculated by various computational schemes for comparison with both theoretical and experimental results
previously reported.
Supported by the Doctorial Initial Foundations of Hainan Normal University (Grant No. 13140252) 相似文献
6.
Tim Dinges Rolf-Dieter Hoffmann Leo van Wüllen Paul Henry Hellmut Eckert Rainer Pöttgen 《Journal of Solid State Electrochemistry》2011,15(2):237-243
The lithium-rich silicide Li4Pt3Si was synthesised from the elements by high-temperature synthesis in a sealed niobium ampoule. Its structure was refined
on the basis of single-crystal X-ray diffraction data: R32, a = 693.7(2), c = 1627.1(4) pm, wR2 = 0.0762, 525 F2 values and 21 variables. The striking structural motifs of the Li4Pt3Si structure are silicon atoms with a slightly distorted trigonal prismatic platinum coordination with short Si–Pt distances
(238–246 pm). Always two trigonal prisms are condensed via a common Pt3 triangle, and these double units built up a three-dimensional network by condensation via common corners. The channels left
by this prismatic network are filled by two crystallographically independent lithium sites in a 3:1 ratio. The single crystal
X-ray data were fully confirmed by neutron powder diffraction and 7Li magic-angle spinning (MAS)–nuclear magnetic resonance (NMR) results. The two distinct lithium sites are well differentiated
by their 7Li isotropic chemical shift and nuclear electric quadrupolar interaction parameters. MAS-NMR spectra reveal signal coalescence
effects above 300 K, indicating chemical exchange between the lithium sites on the millisecond timescale. The spectra can
be simulated with a simple two-site exchange model. From the resulting temperature-dependent correlation times, an activation
energy of 50 kJ/mol is extracted. 相似文献
7.
L. G. Bulusheva A. V. Okotrub V. V. Bashilov V. I. Sokolov 《Russian Chemical Bulletin》2005,54(12):2730-2734
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
8.
Heat capacity of unstable quenched solid solutions (Fe1−xNix)0.96S was measured by DSC (enthalpy method and scanning heating). According to optic microscopy and X-ray powder diffraction,
the samples are homogeneous phase of NiAs type with unit cell parameters changing regularly with composition.
Heat capacity changes with composition irregularly due to the difference in magnetic properties of the end members: C
p/1.96R=4.1 for Fe-rich samples and 3.3 for Ni-rich ones. There is no exact limit between two types of magnetic ordering. Instead,
samples with intermediate composition (0.7<x<0.8) show large fluctuations in C
p due to the inconsistency of alternative (FeS and NiS) types of magnetic ordering. 相似文献
9.
N. A. Sanina T. N. Rudneva S. M. Aldoshin A. N. Chekhlov R. B. Morgunov E. V. Kurganova N. S. Ovanesyan 《Russian Chemical Bulletin》2007,56(1):28-34
The neutral dinuclear iron nitrosyl complex [Fe2(SC3H5N2)2(NO)4] (1) of the “g = 2.03” family with a ligand analogous to natural mercaptohistidine was synthesized by the metathesis reaction
of the thiosulfate ligands in the [Fe2(S2O3)2(NO)4]2− anion with imidazolidine-2-thiolate ligands. The electrochemical determination of nitrogen oxide in solution showed that
compound 1 has a lower NO-donor ability compared to the iron complexes with 1-methylimidazole-2-thiol and imidazole-2-thiol synthesized
earlier. Study of the magnetic properties of polycrystals of 1 demonstrated that the effective magnetic moment at room temperature is ca. 2.45 μB and corresponds to a molecule containing a pair of the noninteracting spins S = 1/2. This is evidence that each iron coordination
unit in complex 1 contains one unpaired electron, and the iron atom is in the low-spin state.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 28–34, January, 2007. 相似文献
10.
Peter Klampfer Primož Benkič Maja Ponikvar Ana Rahten Antonija Lesar Adolf Jesih 《Monatshefte für Chemie / Chemical Monthly》2003,134(1):1-9
Summary. Hydrazinium(+2) fluoroarsenate(III) fluoride was prepared by the reaction of hydrazinium(+2) fluoride and liquid arsenic
trifluoride. N2H6AsF4F is stable at 273 K, but decomposes slowly at room temperature. N2H6AsF4F crystallizes in the orthorhombic space group Pnn2 with a = 774.0(2) pm, b = 1629.2(4) pm and c = 436.6(1) pm; V = 0.5506(3) nm3, Z = 4 and d
c
= 2.461 g cm−3. The structure consists of N2H6
2+ cations, AsF4
− anions, and F− anions and is interconnected by a hydrogen bonding network. Distorted trigonal-bipyramidal AsF4
− units are very weakly interconnected and form chains along the b axis. Bands in the Raman spectrum are assigned to the vibrations of N2H6
+2 cations and AsF4
− anions.
Corresponding author. E-mail: adolf.jesih@ijs.si
Received April 18, 2002; accepted July 15, 2002 相似文献
11.
V. V. Drozdova E. A. Malinina L. V. Goeva I. N. Polyakova N. T. Kuznetsov 《Russian Journal of Inorganic Chemistry》2010,55(1):34-39
A method for the synthesis of the silver(I) complex with the closo-decaborate anion and triphenylphosphine [Ag2(Ph3P)2B10H10]
n
was developed and the structure of this complex was studied. The polymeric chain of the complex is formed with participation
of Ag(I) atoms, which coordinate the B10H102− anions through the apical (B(1)–B(2), B(9)–B(10)) and equatorial (B(3)–B(6), B(5)–B(8)) edges, the metalligand bonding occurring
through three-center two-electron bonds (MHB). The P atoms of two triphenylphosphine molecules are also incorporated in the
inner coordination sphere of the metal: the CN of the silver atom is 4 + 1. 相似文献
12.
One new metal – organic coordination framework formulated as [{Cu(4,4′-bipy)(CH3COO)2}·3H2O]n (1) (where 4,4′-bipy=4,4′-bipyridine) has been hydrothermally synthesised and characterised by elemental analysis, IR and electronic
spectroscopy, variable temperature magnetic moment measurement and single crystal X-ray diffraction study. Single crystal
X-ray analysis reveals that 1 is one dimensional polymeric compound in which acetate ligand shows both mono- and bidentate bonding mode, and 4,4′-bipy
acts as bridging ligand which supports the formation of infinite chains. The global feature of the χ
M
T vs. T curve in 1 is characteristic of moderate antiferromagnetic interaction and the best fit parameters from 300 down to 2 K are found as
J = −78.7 cm−1. 相似文献
13.
I. E. Animitsa E. N. Dogodaeva S. S. Nokhrin O. A. Kosareva A. Ya. Neiman 《Russian Journal of Electrochemistry》2010,46(7):734-740
Perovskite phases Ba3In2ZrO8 and Ba4In2Zr2O11 with the nominal concentration of structural oxygen vacancies 1/9 and 1/12, respectively, were synthesized by solid-phase
and solution methods. X-ray diffraction showed cubic symmetry of both phases with the unit cell parameter a = 0.4193(2) and 0.4204(3) nm, respectively. The absence of superstructural lines resulted in the conclusion on statistical
arrangement of oxygen vacancies. Thermogravimetry and mass spectrometry proved that both phases can reversibly absorb water
from gas phase (pH2O = 2 × 10−2 atm) with observed correlation between the concentration of oxygen vacancies and amount of absorbed water. The total water
amount was up to 0.9 mol per formula unit or, if recalculated for perovskite unit ABO3, 0.3 and 0.23 mol H2O, respectively. The temperature curves of coductivity in the atmosphere with various partial water vapor pressures (pH2O = 3 × 10−5 and 2 × 10−2 atm) showed significantly higher conductivity and lower activation energy (0.52 eV) in humid atmosphere due to proton transfer.
The proton conductivity is up to 5 × 10−4 Ohm−1 cm−1 at 300°C for Ba3In2ZrO8 specimen. IR spectrometry showed that protons in the structure exist primarily in OH-groups. 相似文献
14.
I. A. Leonidov L. L. Surat O. N. Leonidova 《Russian Journal of Inorganic Chemistry》2011,56(11):1706-1712
Phase equilibria in the Ca3(VO4)2-K3VO4-NdVO4 system have been studied. An extensive calcium orthovanadate-based solid solution was found to form with the boundary compositions
as follows: Ca3(VO4)2-Ca9Nd(VO4)7-Ca9.33K2.33(VO4)7-Ca7.88K2.63Nd0.87(VO4)7. The unit cell parameters of the whit-lockite vanadates synthesized increase as the potassium and neodymium contents increase.
Phase transitions from the low-temperature β phase to the β′ centrosymmetrical structure in Ca9.33 − 5z
K2.33 + z
Nd3z
(VO4)7 vanadates have been studied dilatometrically. The increase in the β ai β′ transition temperature caused by potassium is interpreted
as arising from the filling in of vacant cation positions M(4) and M(6). 相似文献
15.
Self-assembling of fullerene C60 into (C60)
n
clusters in aromatic solvents was studied. The role of the π-π interactions and dispersion forces in the (C60)
n
cluster formation in these media is demonstrated using the data on the solubility of fullerene C60 in these solvents and their ionization potentials and also spectral characteristics of fullerene C60 in the range of 326–340 nm in different solvents. 相似文献
16.
Roman Zaremba Ute Ch. Rodewald Rainer Pöttgen 《Monatshefte für Chemie / Chemical Monthly》2007,138(9):819-822
Summary. The isotypic indides RE
5Pt2In4 (RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu) were synthesized by arc-melting of the elements and subsequent annealing. They were investigated
via X-ray powder diffraction. Small single crystals of Gd5Pt2In4 were grown via slow cooling and the structure was refined from X-ray single crystal diffractometer data: Pbam, a = 1819.2(9), b = 803.2(3), c = 367.6(2) pm, wR
2 = 0.089, 893 F
2 values and 36 parameters. The structure is an intergrowth variant of distorted trigonal and square prismatic slabs of compositions
GdPt and GdIn. Together the platinum and indium atoms build up one-dimensional [Pt2In4] networks (292–333 pm Pt–In and 328–368 pm In–In) in an AA stacking sequence along the c axis. The gadolinium atoms fill distorted square and pentagonal prismatic cages between these networks with strong bonding
to the platinum atoms. 相似文献
17.
E. Vessally M. Nikoorazm A. Esmaili H. Ghoudarzi Afshar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(4):631-635
Thermal internal energy gaps, ΔE
s−t; enthalpy gaps, ΔH
s−t; Gibbs free energy gaps, ΔD
s−t, between singlet (s) and triplet (t) states of R2C4H2M (M = C, Si, and Ge) were calculated at B3LYP/6-311++G** level of theory. The ΔG
s−t of R2C4H2C was increased in the order (in kcal/mol): R = −CH3 (−10.51) > −H (−9.59) > i-Pr (−9.51) > t-Bu (−8.98). While, the ΔG
s−t of R2C4H2Si and R2C4H2Ge were increased in the order (in kcal/mol): −CH3 (17.01) > i-Pr (15.30) > −H (15.26) > t-Bu (14.35) and -H (22.79) > −CH3 (22.69) > i-Pr (21.66) > t-Bu (21.01), respectively. 相似文献
18.
Ji-min Yang Yan Yao Run-zhi Zhang Ai-de Sun Bao-hui Li Hong-zhi Lu Qi-ying Xia 《Journal of solution chemistry》2009,38(4):429-439
Osmotic coefficients and water activities for the Li2B4O7+LiCl+H2O system have been measured at T=273.15 K by the isopiestic method, using an improved apparatus. Two types of osmotic coefficients, φ
S and φ
E, were determined. φ
S is based on the stoichiometric molalities of the solute Li2B4O7(aq), and φ
E is based on equilibrium molalities from consideration of the equilibrium speciation into H3BO3,B(OH)4− and B3O3(OH)4−. The stoichiometric equilibrium constants K
m
for the aqueous speciation reactions were estimated. Two types of representations of the osmotic coefficients for the Li2B4O7+LiCl+H2O system are presented with ion-interaction models based on Pitzer’s equations with minor modifications: model (I) represents
the φ
S data with six parameters based on considering the ion-interactions between three ionic species of Li+, Cl−, and B4O72−, and model (II) for represents the φ
E data based on considering the equilibrium speciation. The parameters of models (I) and (II) are presented. The standard deviations
for the two models are 0.0152 and 0.0298, respectively. Model (I) was more satisfactory than model (II) for representing the
isopiestic data. 相似文献
19.
Sofia Nikolaou Daniela M. Tomazela Marcos N. Eberlin Henrique E. Toma 《Transition Metal Chemistry》2008,33(8):1059-1065
The polymetallic [Ru3O(CH3COO)6(py)2(BPE)Ru(bpy)2Cl](PF6)2 complex (bpy = 2,2′-bipyridine, BPE = trans-1,2-bis(4-pyridil)ethylene and py = pyridine) was assembled by the combination of an electroactive [Ru3O] moiety with a [Ru(bpy)2(BPE)Cl] photoactive centre, and its structure was determined using positive ion electrospray (ESI-MS) and tandem mass (ESI-MS/MS)
spectrometry. The [Ru3O(CH3COO)6(py)2(BPE)Ru(bpy)2Cl]2+ doubly charged ion of m/z 732 was mass-selected and subject to 15 eV collision-induced dissociation, leading to a specific dissociation pattern, diagnostic
of the complex structure. The electronic spectra display broad bands at 409, 491 and 692 nm ascribed to the [Ru(bpy)2(BPE)] charge-transfer bands and to the [Ru3O] internal cluster transitions. The cyclic voltammetry shows five reversible waves at −1.07 V, 0.13 V, 1.17 V, 2.91 V and
−1.29 V (vs SHE) assigned to the [Ru3O]−1/0/+1/+2/+3 and to the bpy0/−1 redox processes; also a wave is observed at 0.96 V, assigned to the Ru+2/+3 pair. Despite the conjugated BPE bridge, the electrochemical and spectroelectrochemical results indicate only a weak coupling
through the π-system, and preliminary photophysical essays showed the compound decomposes under visible light irradiation. 相似文献
20.
D. A. Loginov M. M. Vinogradov Z. A. Starikova P. V. Petrovskii A. R. Kudinov 《Russian Chemical Bulletin》2007,56(11):2162-2165
The visible light irradiation of the [(η5-C6H7)Fe(η-C6H6)]+ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η5-C6H7)Fe(MeCN)3]+ (2). The reaction of 1 with ButNC in MeCN produced the stable isonitrile complex [(η5-C6H7)Fe(ButNC)3]+ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P5) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η5-C6H7)Fe(μ-η:η-cyclo-P5)FeCp*]+ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P5). The structure of the complex [3]PF6 was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007. 相似文献