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1.
The dissolution of silver nanoparticles in their reaction with aqueous HNO3 solubilized to an reverse micelle solution of sodium bis(2-ethylhexyl)sulfosuccinate in decane is studied spectrophotometrically. A physicochemical model is advanced for quantifying the process kinetics on th basis of the following autocatalytic scheme: Ag0 + H+ + NO 3 ? → Ag+ + products (k 1), and Ag0 + Ag+ + NO 3 ? → 2Ag+ + products (k 2). The effective rate constant k 2 decreases with decreasing solubilization capacity V S/V O (where V S is the volume of the solubilized dispersed aqueous phase and V O is the volume of the micelle solution); the solubilization capacity determines the size of the micelle cavities in which the reaction between Ag0 and HNO3 occurs: k 2 = 74 (V S/V O) · 100% ≈ 3.8%), 41 (2.9), and 35 (2.0) L/(mol s). The effective constant k 1 is determined with a high uncertainty; the effect of V S/V O on k 1 has the opposite tendency.  相似文献   

2.
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   

3.
The low-temperature heat capacity of Na2Lu (MoO4)(PO4) was measured by adiabatic calorimetry in the range of 7.47–345.74 K. The experimental data were used to calculate the thermodynamic functions of Na2Lu (MoO4)(PO4). At 298.15 K, the following values were obtained: C p 0 (298.15 K) = 237.7 ± 0.1 J/(K mol), S 0(298.15 K) = 278.1 ± 0.8 J/(K mol), H 0(298.15 K) ? H 0 (0 K) = 42330 ± 20 J/mol, and Φ0(298.15 K) = 136.1 ± 0. 3 J/(K mol). A heat capacity anomaly was found in the range of 10-67 K with a maximum at T tr = 39.18 K. The entropy and enthalpy of transition are ΔS = 12.39 ± 0.75 J/(K mol) and ΔH = 403 ± 16 J/mol. The thermal investigation of sodium lutetium molybdate phosphate in the high-temperature range (623–1223 K) was performed using differential scanning calorimetry. It was found that during melting in the range of 1030–1200 K, Na2Lu(MoO4)(PO4) degrades to simpler compounds; the degradation scenario is verified by X-ray powder diffraction.  相似文献   

4.
The low-temperature heat capacity of K2MoO4 was measured by adiabatic calorimetry. The smoothed heat capacity values, entropies, reduced Gibbs energies, and enthalpies were calculated over the temperature range 0–330 K. The standard thermodynamic functions determined at 298.15 K were C p ° (298.15 K) = 143.1 ± 0.2 J/(mol K), S°(298.15 K) = 199.3 ± 0.4 J/(mol K), H°(298.15 K)-H°(0) = 28.41 ± 0.03 kJ/mol, and Φ°(298.15 K) = 104.0 ± 0.4 J/(mol K). The thermal behavior of potassium molybdate at elevated temperatures was studied by differential scanning calorimetry. The parameters of polymorphic transitions and fusion of potassium molybdate were determined.  相似文献   

5.
A new dinuclear oxidovanadium(V) complex, [V2O2(μ-O)2L2], where L is the monoanionic form of 2-[(2-methylaminoethylimini)methyl]-4-trifluoromethoxyphenol (HL), was prepared and characterized by IR, UV-Vis and 1H NMR spectra, as well as single crystal X-ray diffraction (CIF file CCDC no. 1567062). The complex crystallizes as the monoclinic space group P21/c with unit cell dimensions a = 12.974(3), b = 6.572(2), c = 17.205(3) Å, β = 107.300(3)°, V = 1400.7(5) Å3, Z = 2, R1 = 0.0879, wR2 = 0.1208, GOOf = 1.068. X-ray analysis indicates that the complex is a centrosymmetric dinuclear oxidovanadium(V) species with the V atoms in octahedral coordination. The Schiff base and the complex were evaluated for their antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescence) activities. The complex has the most activity against B. subtilis with the MIC value of 1.2 μg mL–1.  相似文献   

6.
Adiabatic calorimetry is used to measure the low-temperature heat capacity of Na2Er(MoO4)(PO4)from 6.41 to 347.87 K. Experimental data are used to calculate the thermodynamic functions of Na2Er(MoO4)(PO4), which at 298.15 K are as follows: C p 0 (298.15 K) = 243,3 ± 0.4 J/(K mol), S 0(298.15 K) = 312.8 ± 0.8 J/(K mol), H 0(298.15 K) ? H 0(0 K) = 45280 ± 90 J/mol, and Φ0(298.15 K) = 136.1 ± 0.3 J/(K mol). A diffuse heat-capacity anomaly associated with splitting of the Stark levels (Schottky anomaly) is discovered in the low-temperature region.  相似文献   

7.
The structure of a mixed-ligand complex tris-(dipivaloylmethanato)(ethylendiamine)yttrium(III) [Y(en)(dpm)3] is studied at 150(2) K by single crystal XRD. The crystallographic data for C35H65N2O6Y are as follows: space group P21/c, a = 10.3771(3) Å, b = 26.3566(8) Å, c = 14.8412(4) Å, β = 100.385(2)°, V = 3992.6(2) Å3, Z = 4. The structure is molecular. The coordination environment of yttrium atoms is square antiprismatic; the Y–О distances are 2.2597(13)-2.3760(12) Å and Y–N distances are 2.5381(16) Å and 2.5499(17) Å.  相似文献   

8.
The energies and structural and spectroscopic characteristics of model М n V20O50 systems corresponding to compounds of the V20O50 oxovanadate cluster with alkali metal atoms (M = Li, K; n = 1–20) have been calculated by the density functional theory method (B3LYP). It has been demonstrated that, in the K n V20O50 compounds, all the metal atoms are coordinated in the outer sphere to the edges of the hollow dodecahedral V20O50 cage to form three-center Ot?K?Ot bridges with terminal oxygen atoms. In the Li n V20O50 compounds, the metal atoms can be coordinated both outside and inside the V20O50 cage. At n = 4, the most favorable isomer is endohedral Li4O4@V20O46 in the quintet state (S = 5), in which the four Li atoms are located in the inner cavity of the inverted O4@V20O46 isomer of the oxovanadate cluster with four O atoms oriented to the cage center and form with them a corrugated eight-membered ring Li4O4. The decrease in energy caused by the formation of the endohedral isomer (4Li + V20O450 → Li4O4@V20O46) is estimated at ~377 kcal/mol. The exohedral isomer 4Li ? V20O50 (S = 5), in which the Li atoms are coordinated to the outside of the V20O50 cage, is ~23 kcal/mol less favorable. For the other members of the Li series with n from 4 to 20, the endohedral isomers with the inner Li4O4 ring remain preferable. At n > 4, the extra Li atoms fill the outer sphere of the cage, being coordinated to its edges to form three-center Ot?Li?Ot bridges with terminal oxygen atoms. The specific energy of formation of Li n V20O50 (by the scheme nLi + V20O450 → Li4O4@V20O46Lin-4) per Li atom monotonically decrease from ~98 (n = 2) to ~80 kcal/mol (n = 20). For K n V20O50, these energies are ~20?25 kcal/mol lower than for the lithium analogues and decrease from ~80 (n = 2) to ~64 kcal/mol (n = 12). The atoms of both alkali metals in the M n V20O50 systems have large positive effective charges (0.85e?0.92e for K and 0.65e?0.78e for Li), which also monotonically decrease with increasing n. The addition of each alkali metal atom is accompanied by its ionization (М → М+) along with the reduction of one of the neighboring pentavalent vanadium atoms to the tetravalent state (VV → VIV) and localization of the unpaired electron in its 3d shell. For all Li n V20O50 complexes, the states with maximal multiplicity and parallel spins are the most preferable.  相似文献   

9.
Ferrites of composition ErMIFe2O5 (MI = Li, Na, K, Cs) were synthesized by a solid-phase method. The structure of the ferrites was for the first time studied by X-ray powder diffraction. Crystal systems, unit cell parameters, and X-ray and pycnometric densities were determined. For ErLiFe2O5, a = 10.510 Å, c = 14.270 Å, V°= 1616.16 Å3, Z = 16, V subcell ° = 101.01 Å3, ρx = 6.01 g/cm3, ρpyc = 5.97 ± 0.04 g/cm3; for ErNaFe2O5, a = 10.519 Å, c = 15.510 Å, V° = 1759.56 Å3, Z = 16, V subcell ° = 109.90 Å3, ρx = 5.77 g/cm3, ρpyc = 5.72 ± 0.08 g/cm3; for ErKFe2O5, a = 11.050 Å, c = 15.480 Å, V° = 1937.33 Å3, Z = 16, V subcell ° = 121.08 Å3, ρx = 5.46 g/cm3, ρpyc = 5.41 ± 0.04 g/cm3; and for ErCsFe2O5, a = 10.78 Å, c = 16.01 Å, V° = 1905.37 Å3, Z = 16, V subcell ° = 119.09 Å3, ρx = 6.86 g/cm3, ρpyc = 6.61 ± 0.01 g/cm3.  相似文献   

10.
The (VO)0.09V0.18Mo0.82O3 · 0.54H2O microrods of hexagonal symmetry system with the unit cell parameters a = 10.586 Å and c = 3.698 Å were obtained for the first time under hydrothermal conditions (T = 160°C, τ = 30?50 h). Particles were 1–2 μm in diameter and up to 45 μm in length. The compound is thermally stable up to 469°C. The core-electron Mo3d, V2p, and O1s and valence-band X-ray photoelectron spectra and IR spectra of the samples were studied. The molybdenum atoms in the complex oxide have the oxidation state Mo6+. The vanadium atoms introduced into the h-MoO3 lattice in molybdenum positions have the oxidation state V5+. Approximately one-third of vanadium atoms as vanadyl ions (VO)2+ are located in the channels of h-MoO3 lattice, thus stabilizing the latter.  相似文献   

11.
New ferrites ErMFe2O5 (M = Li, Na, K) were synthesized from erbium and iron(III) oxides and lithium, sodium, and potassium carbonates by solid-state annealing. According to X-ray powder diffraction, these compounds crystallize in the orthorhombic system with the following unit cell parameters: ErLiFe2O5, a = 10.510 Å, b = 10.776 Å, c = 14.270 Å, V 0 = 1616.16 Å3; Z = 16, V subcell 0 = 101.01 Å3, ρX = 6.01 g/cm3, ρpycn = 5.97 ± 0.05 g/cm3; ErNaFe2O5, a = 10.519 Å, b = 10.785 Å, c = 15.510 Å, V 0 = 1759.56 Å3, Z = 16, V subcell 0 = 109.90 Å3, ρX = 5.77 g/cm3, ρpycn = 5.72 ± 0.08 g/cm3; ErKFe2O5, a = 10.050 Å, b = 11.320 Å, c = 15.480 Å, V 0 = 1937.33 Å3, Z = 16, V subcell 0 = 121.08 Å3, ρX = 5.46 g/cm3, ρpycn = 5.41 ± 0.04 g/cm3.  相似文献   

12.
The syntheses and crystal structures of the layered coordination polymers M(C8H8NO2)2 [M = Mn (1), Co (2), Ni (3) and Zn (4)] are described. These isostructural compounds contain centrosymmetric trans-MN2O4 octahedra as parts of infinite sheets; the ligand bonds to three adjacent metal ions in μ3-N,O,O′ mode from both its carboxylate O atoms and its amine N atom. In each case, weak intra-sheet N–H?O and C–H?O hydrogen bonds may help to consolidate the structure. Crystal data: 1, C16H16MnN2O4, M r = 355.25, monoclinic, P21/c (No. 14), a = 10.6534(2) Å, b = 4.3990(1) Å, c = 15.5733(5) Å, β = 95.1827(10)°, V = 726.85(3) Å3, Z = 2, R(F) = 0.026, wR(F 2) = 0.067. 2, C16H16CoN2O4, M r = 359.24, monoclinic, P21/c (No. 14), a = 10.6131(10) Å, b = 4.3374(4) Å, c = 15.3556(17) Å, β = 95.473(4)°, V = 703.65(12) Å3, Z = 2, R(F) = 0.041, wR(F 2) = 0.091. 3, C16H16N2NiO4, M r = 359.02, monoclinic, P21/c (No. 14), a = 10.6374(4) Å, b = 4.2964(2) Å, c = 15.2827(8) Å, β = 95.9744(14)°, V = 694.66(6) Å3, Z = 2, R(F) = 0.028, wR(F 2) = 0.070. 4, C16H16N2O4Zn, M r = 365.68, monoclinic, P21/c (No. 14), a = 10.6385(5) Å, b = 4.2967(3) Å, c = 15.2844(8) Å, β = 95.941(3)°, V = 694.89(7) Å3, Z = 2, R(F) = 0.038, wR(F 2) = 0.107.  相似文献   

13.
Ytterbium alkali-metal chromites YbMCr2O5 (M = Li, Na, K, Cs) were synthesized by a ceramic procedure from the corresponding oxides and carbonates. Their crystal systems and unit cell parameters were determined by the homology method: for YbLiCr2O5, a = 10.34 Å, b = 10.62 Å, c = 15.05 Å, Z = 16, V o = 1653.74 Å3, ρX-ray = 5.85 g/cm3, ρpycn = 5.81 ± 0.03 g/cm3; for YbNaCr2O5, a = 10.30 Å, b = 10.56 Å, c = 16.46 Å, Z = 16, V o = 1790.32 Å3, ρX-ray = 5.64 g/cm3, ρpycn = 5.59 ± 0.07 g/cm3; for YbKCr2O5, a = 10.33 Å, b = 10.63 Å, c = 19.93 Å, Z = 16, V o = 2188.47 Å3, ρX-ray = 5.95 g/cm3, ρpycn = 5.91 ± 0.03 g/cm3; and for YbCsCr2O5, a = 10.34 Å, b = 10.63 Å, c = 18.43 Å, Z = 16, V o = 2025.72 Å3, ρX-ray = 5.19 g/cm3, ρpycn = 5.16 ± 0.05 g/cm3.  相似文献   

14.
The structure of 1,8-bis(fluoroboro)-2,7,9,14,15,20-hexaoxa-3,6,10,13,16,19-hexaaza-4,5,11,12-tetraphenyl-17,18-bisc(tert-butylamino)-bicyclo[6.6.6]eicosa-3,5,10,12,16,18-hexaene(2−)iron(2+) tris-dioximate clathrochelate was determined by X-ray diffraction (XRD) analysis. The compound has a molecular structure and crystallizes as triclinic crystals: a = 10.7673(2) Å, b = 11.9520(4) Å, c = 22.5473(7) Å, α = 75.729(1)°, β = 89.161(1)°, γ = 65.334(1)°, V = 2542.64(13) Å3, Z = 2, space group 1. P1ˉ. Original Russian Text Copyright ? 2007 by A. B. Burdukov, N. V. Pervukhina, M. A. Vershinin, and Ya. Z. Voloshin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 366–369, March–April, 2007.  相似文献   

15.
The structures of tris-hexafluoroacetylacetonates Al(hfa)3 and Sc(hfa)3·H2O are determined by single crystal X-ray crystallography (Bruker-Nonius X8 Apex diffractometer, MoK α radiation, T = 150(2) K). The Al(hfa)3 complex is trigonal, a = 17.8944(11) Å, c = 12.4061(11) Å, P-3c1 space group, V = 3440.3(4) Å3, Z = 6, R = 0.076. The Sc(hfa)3·H2O complex is monoclinic, a = 16.0926(4) Å, b = 14.7980(3) Å, c = 24.4020(5) Å, β = 125.641(1)°, P21/c space group, V = 4722.54(18) Å3, Z = 8, R = 0.060. The structures of the complexes are formed by neutral molecules; the coordination environment of the metal atom involves six oxygen atoms of three β-diketone ligands (Al(hfa)3) and, additionally, a water oxygen atom (Sc(hfa)3·H2O). The shortest Al...Al distance is 6.203(6) Å. The Sc(hfa)3·H2O molecules are joined in dimers by hydrogen bonds with Sc...Sc separations of 5.6992(8) Å and 5.6853(8) Å. In the crystals, the molecules are joined by van der Waals interactions, moreover, there are intermolecular contacts F...H ~ 2.5 Å in the structure of Sc(hfa)3·H2O.  相似文献   

16.
A novel metal chalcogenide HgCd4S5 (1) was synthesized from solid-state reactions and structurally characterized. Compound 1 crystallizes in the space group C2221 of the orthorhombic system with four formula units in a cell: a = 12.5661(5) Å, b = 7.2551(5) Å, c = 10.7520(7) Å, V = 980.2(1) Å3, Cd4HgS5, M r = 810.49, D c = 5.492 g/cm3, S = 1.010, μ(MoK α) = 25.128 mm?1, F(000) = 1408, R = 0.0611 and wR = 0.1495. Compound 1 is characterized by a 3-D cadmium sulfide framework structure with the infinite mercury sulfide chains located in the cavities.  相似文献   

17.
2-Mercapto-5-methyl-1,3,4-thiadiazol (MMTD) and 2,5-dimercapto-1,3,4-thiadiazol (DMTD) were studied by differential pulse cathodic stripping voltammetry (DPCSV). The influence of buffer, pH, accumulation potential (Eacc), and accumulation time (tacc) was investigated. It was stated that the concentration of the buffer affects the height of DPCSV peaks. The best analytical signals were recorded in acetate buffer at pH 4.3 and a buffer concentration of 0.01 mol/L for MMTD and 0.02 mol/L for DMTD, Eacc = 0.2 V, and tacc = 120 s for MMTD and 180 s for DMTD. A linear dependence was found from 1 to 8 × 10?8 mol/L for MMTD and from 1 × 10?8 to 1 × 10?7 mol/L for DMTD. The influence of cations [Cu(II), Co(II)] was also considered.  相似文献   

18.
A solvate [Cu(CF3COCHCOCH3)2(CH3COCH3)] has been synthesized and characterized for the first time. According to X-ray structural data (diffractometer X8 APEX BRUKER, radiation MoK α, T = 150 K), it crystallizes in the monoclinic crystal system, space group P21/c, a = 8.9940(4) Å, b = 22.3966(11) Å, c = 8.1884(3) Å, β = 92.705(2)°, V = 1647.59(12) Å3, Z = 4, d calc = 1.725 g/cm3, final R = 0.0272. The structure is molecular. In the equatorial plane the atom Cu(II) is surrounded with four oxygen atoms of two chelating ligands (CF3COCHCOCH3)?; Cu-O distances 1.927–1.937 Å, O-Cu-O angles 86.18–93.30° and 170.18–175.67°. Square coordination of Cu is complemented to the square-pyramidal one by the oxygen atom of an acetone molecule behaving as an axial ligand; Cu-Oacetone 2.342 Å, O-Cu-Oacetone 89.66–100.11°. In the studied compound disorder of one of the chelate ligands implies the co-existance of the molecules in the cis- and trans-configuration in the crystal under ratio 54.6:45.4. In air the solvate rapidly degrades losing acetone, while in a sealed vessel melts around 313 K. Temperature dependence of equilibrium vapor pressure of acetone over the complex was measured with the static spoon gauge technique, thermodynamic characteristics of its dissociation process being derived: [Cu(CF3COCHCOCH3)2(CH3COCH3)]s = [Cu(CF3COCHCOCH3)2]s + CH3COCH3g, ΔH av 0 = 49.6(3) kJ/mol, ΔS av 0 = 152(1) J/(mol K), ΔG av 0 = 4.30(2) kJ/mol.  相似文献   

19.
Two coordination polymers, {[Cd(L1)2(L2)] · 0.25H2O} n (I) and {[Cd(L1)(L3)H2O] · 2H2O} n (II) (L1 = 2-pyrimidineamidoxime, L2 = 4-sulfobenzoate dianion and L3 = 5-sulfosalicylate dianion), has been synthesized and structurally characterized by single-crystal X-ray diffraction (CIF files CCDC nos. 1565646 (I) and 1565728 (II)). Complex I crystallizes in monoclinic space group P21/n with a = 10.1462(3), b = 16.0152(5), c = 14.0349(5) Å, β = 93.267(3)°, V = 2276.87(13) Å3, C68H66N32O29S4Cd4, M = 2373.36, ρcalcd = 1.731 g/cm3, μ(MoKα) = 1.109 mm?1, F(000) = 1186, GOOF = 0.806, Z = 1, the final R1 = 0.0287 and wR2 = 0.0733 for I > 2σ(I). Complex II crystallizes in monoclinic space group P21 with a = 6.882(2), b = 17.138(2), c = 7.883(2) Å, β = 103.83(3)°, V = 902.8(4) Å3, C12H16N4O10SCd, M = 520.75, ρcalcd = 1.916 g/cm3, μ(MoKα) = 1.388 mm?1, F(000) = 520, GOOF = 1.047, Z = 2, the final R1 = 0.0739 and wR2 = 0.2041 for I > 2σ(I). Crystal structural analysis reveals that complex I possesses the corrugated 1D chain structure extending along the \([\bar 101]\) direction. However, complex II displays a 2D coordination network lying on the ab crystal plane, which can be simplified as a binodal 3-connected 63 topological network by considering Cd2+ ions and L3 ligands as 3-connected nodes. Their photoluminescent and thermal properties were also investigated.  相似文献   

20.
The single crystals of the Np(V) complex (NH4)[NpO2(CO3)] (I) were synthesized and studied by X-ray diffraction. At 100 K, the crystals are hexagonal, space group P63 μmc, a = 5.0734(1) Å, c = 10.9191(2) Å, V= 243.399(11) Å3, Z = 2, ρ(calcd) = 4.735 g/cm3. The absorption spectra of a crystal of I in the visible and infrared ranges were measured.  相似文献   

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