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41.
Tiao-Hsu Chang 《中国化学会会志》1966,13(4):143-149
The acid dissociation constants of dihalogenated 8-hydroxyquinaldines and the stability constants of their chelates with Zn[II], Ni[II], Co[II], Pb[II], Cd[II], Mn[II], and Mg[II] have been determined. The Calvin-Bjerrum potentiometric titration technique was used in studying the behavior of these substances. The order of decreasing stability of the metal chelates Zn, Nc>Co>Pb>Cd>Mn>Mg is similar to the stability sequence generally obtained for divalent metals, and the order of decreasing stability of dihalogenated 8-hydroxyquinaldines to form the metal chelates with metal ions is I>Br>Cl. Spot test reactions of dihalogenated 8-hydroxyquinaldines and 8-hydroxyquinolines with the metal ions also have been investigated. 相似文献
42.
Reaction of 1,4-diisocyanobenzene or 4-isocyanobenzonitrile with trans-W(N(2))(2)(DPPE)(2) (DPPE = 1,2-bis(diphenylphosphino)ethane) produced cis-WL(2)(DPPE)(2), where L = 1,4-diisocyanobenzene or 4-isocyanobenzonitrile. cis-(CNC(6)H(4)NC)(2)W(DPPE)(2) crystallizes in the triclinic space group P&onemacr;, with a = 12.848(3) ?, b = 13.596(3) ?, c = 19.072(3) ?, alpha = 78.99(2) degrees, beta = 70.66(2) degrees, gamma = 65.26(2) degrees, V = 2849.8(11) ?(3), and Z = 2. cis-(NCC(6)H(4)NC)(2)W(DPPE)(2) crystallizes in the triclinic space group P&onemacr;, with a = 12.712(3) ?, b = 13.700(3) ?, c = 19.109(3) ?, alpha = 77.91(2) degrees, beta = 70.63(2) degrees, gamma = 64.76(2) degrees, V = 2830.7(13) ?(3), and Z = 2. Both compounds possess a distorted octahedral geometry about the metal center, with the two isocyanide ligands cis to one another. The isocyanide ligands are substantially bent along the CNC axis of the isocyanide group coordinated to tungsten. For the complex containing the symmetric ligand, CNC(6)H(4)NC, the mean CNC angle for the coordinated end of the isocyanide is 139.1(11) degrees, the average W-C bond length is 1.86(1) ?, and the C&tbd1;N bond lengths have a mean value of 1.30(2) ?. These data indicate substantial back-donation from an electron-saturated tungsten atom. This is supported spectroscopically, with substantial shifts to lower wavenumbers for the C-N stretching frequencies of the coordinated isocyanide groups. Similar trends are observed in cis-(NCC(6)H(4)NC)(2)W(DPPE)(2). Both compounds contain electron-rich metals surrounded by large ligands which apparently protect the metals from atmospheric oxidation. The isocyanide ligands in both complexes contain a second coordinating group pointing away from the metal into the environment surrounding the molecules, providing the potential for polymetallic complexes containing metals in a variety of oxidation states. 相似文献
43.
The mixture of silver iodide and ferrocene is used to prepare the membrane of iodide ion-selective electrode. The interference of sulfide can be reduced by the addition of cupric ion in the test solution. Ethylene glycol is determined by potentiometric titration using iodine ion-selective electrode as an indicator electrode. 相似文献
44.
A novel compound, [Co(phen)3][V10O26]·H2O, was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic space group Ccca with a=13.447(3), b=29.936(6), c=23.252(5) Å, V=9360(3) Å3, Z=8 and R=0.0285. Data were collected on a Rigaku R-AXIS RAPID IP diffractometer at 293 K in the range of 1.36<θ<24.99°. The structure of the compound consists of vanadium oxide layers, which are built up from the infinite VO4 chains by corners and edges sharing. The [Co(phen)3]2+ complexes occupy the interlayer space and contact each other via π−π stacking interactions of the phen groups to form infinite one-dimensional chains. 相似文献
45.
Very low pressure photolysis (VLPØ) of chlorine nitrate was performed in a quartz Knudsen cell. The light source was a 2500 W high-pressure xenon lamp, and a modulated molecular-beam mass spectrometer was used to monitor the concentration of ClONO2 and photolysis products. Because of the low pressures used (? 10?3 torr) and the short residence time in the cell (≈1 s), secondary reactions were unimportant and the primary products could be directly identified. The primary photolysis products (λ ≈ 2700 Å) are atomic chlorine and NO3 free radical. Chlorine atoms were identified both by the appearance of Cl2 (wall recombination product; the walls were not poisoned) and by HCl produced when C2H6 was added to the cell. Nitrate free radical was directly identified as a mass peak at m/e = 62, as well as by chemical titration with nitric oxide: NO3 + NO → 2NO2. It was verified by direct tests that the peak at m/e = 62 did not arise from possible HNO3 contamination or from N2O5, a possible secondary product. This titration reaction was used to measure quantitatively a lower limit to the primary quantum yield, φ ? 0.5 ± 0.3. This represents a lower limit because of the unknown extent of the secondary photolysis of NO3 under our conditions. We believe this to be the first observation using mass spectrometry of the NO3 free radical. The quantum yield for atomic chlorine is φ = 1.0 ± 0.2. N2O was used to test for O(1D) according to the reaction, O(1D) + N2O → products; none was observed. Triplet oxygen, O(3P) was observed to the extent of ≈ 10% by the reaction O(3P) + NO2 → NO + O2, but this yield can also be due to the photolysis of NO3 free radical produced in the primary step. We conclude that the predominant reaction pathway is . 相似文献
46.
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Theoretical and Mathematical Physics - The initial-boundary value problems for the matrix Lakshmanan–Porsezian–Daniel system are studied by utilizing the Fokas unified transform... 相似文献
48.
Hu Wentao Chen Cuixia Shi Yufeng Chen Ze 《Methodology and Computing in Applied Probability》2022,24(2):831-874
Methodology and Computing in Applied Probability - Risk measures for tail risk have an important application in the dynamic portfolio insurance strategies. We propose a new risk measure called... 相似文献
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