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41.
Kikuo Miyokawa Masayuki Itoh Takummi Etoh Setsuko Kinoshita Isao Masuda 《Thermochimica Acta》1985,96(1):227-234
Kinetic and thermodynamic aspects of the axial base dissociation of solid Co(salen) (X-py) complexes, X = H (1), 3-Me (2), 4-Me (3), 3,4-Me2 (4), 3,5-Me2 (5), 3-NH2 (6), 3-Cl (7), 3-CN (8), 4-CN (9), have been investigated by means of TG-DSC and isothermal weight-loss measurements. These adducts endothermically dissociate the axial base giving rise to the oxygen-active Co(salen) complex. The axial base dissociation reactions fit the contracting disc equation and the kinetic compensation effect is observed for all the adducts excepting Adducts 4–6. For the remaining adducts the kinetic and thermodynamic stabilities of the Co-(X-py) bond are found to increase linearly with increasing Hammett's substitution constants of X except for Adducts 3 and 9. These results are discussed in terms of the σ and π interactions between cobalt(II) and substituted pyridine. Factors dominating the kinetic bond stability are briefly discussed. 相似文献
42.
Cyclisation of the title compounds leads to mixtures of the expected 4H-cyclopental[b]pyrrol-4-ones (1), the corresponding 6-ones (3) by a single rearrangement, and the cyclopenta[c]pyrrol-4-ones (4) by a double rearrangement, the proportions depending upon the substituents.The 1H NMR spectra of 2-methyl-4H-cyctopenta[b]thiophen-6-one (3f) shows 6J long range coupling, but this is absent in the corresponding pyrroles (3c,d). The 13C spectra of 1 and 3 cannot be interpreted on the basis of substituent chemical shifts in pyrroles and thiophens, and are clearly -CH = CH-X (X = NMe, NPh, S) bridged derivatives of cyclopent-2-enone. 相似文献
43.
The question of possible neutral intermediates which may lie on the reaction pathway in going from longifolene to isolongifolene has been investigated using BF3·Et2O-AcOD and D3PO4-dioxane, as reagents. It has been found that longicyclene is not an obligatory intermediate. The mode of cleavage of cyclopropane ring in longicyclene has been investigated. 相似文献
44.
阐述了高耸柔性结构振动主动控制的必要性、基本概念及其关键技术,综述了其研究现状及存在的问题,并指出高耸柔性结构机敏化/智能化是确保结构安全性与耐久性的重要途径。 相似文献
45.
The phosphorescence spectra of naphthalene-octafluoronaphthalene and durene-octafluoronaphthalene at 4.2 K reveal a localized exciton emission from octafluoronaphthalene, a weak intercomponent triplet-states quasi-resonance and a weak exciton-phonon coupling. 相似文献
46.
The vertical ionization potentials of difluoramine are calculated by perturbation corrections to Koopmans' theorem. The calculation shows that difluoraimine has three overlapping bands between 15 and 16 eV. The calculated results compare well with the experimental values. The photoelectron spectrum of difluoramine is compared with that of OF2 and CH2F2. 相似文献
47.
Molybdenum was reported to be precipitated quantitatively by 8-hydroxyquinoline in the pH range 3.3–7.6, the precipitated compound having the composition MoO2(ox)2. The pH range reported and the composition of the complex do not seem to be compatible with present knowledge of the pH stability of anionic and cationic molybdenum. It is now shown that under defined conditions, the precipitate is not formed at pH values higher than 2.24. In several estimations of other metals, molybdenum was masked by using a complexone at high pH values. It is now pointed out, that maintaining the solution at high pH value is itself sufficient and no other external complexing agent is necessary for masking molybdenum. 相似文献
48.
The sulphide-selective electrode is applicable to the determination of dithiooxamide by titration with silver nitrate. The effect of the alkali content of the solutions on the reaction has been studied. The reaction products are silver sulphide, oxalic acid, and nitric acid. If the alkali concentration of the solution is lower than that equivalent to the acid formed during the titration, the amount of sulphide produced by hydrolysis decreases and the equilibrium potential is established more slowly.The determination is rapid and accurate in the presence of 1 M sodium hydroxide. 相似文献
49.
Silver(I) and N,N'-bis(2-hydroxyethyl)dithiooxamide (H2X) in acidic solutions, form a series of water-soluble polynuclear complexes. These complexes can be represented by two general formulae: H2qAgpXq and H2q-1AgpXq with q=1,2,3 and p=q, q-1. 相似文献
50.
A. A. Pasynskii I. L. Eremenko Yu. V. Rakitin B. Orazsakhatov V. M. Novotortsev O. G. Ellert V. T. Kalinnikov 《Journal of organometallic chemistry》1981,210(3):377-384
Isostructural heterotrinuclear complexes (C5H5CrSCMe3)2S · M(CO)5 (II–IV) were isolated from photochemical reactions between the antiferromagnetic complex (C5H5CrSCMe3)2S (I) (with the Cr---Cr bond 2.689 Å long and with the exchange parameter −2J = 430 cm−1) and metal hexacarbonyls, M(CO)6, where M is Cr, Mo, or W. According to the X-ray structural data on III and IV, complex I plays the role of an unusual antiferromagnetic ligand L bound to M through the sulphide bridge (M–S 2.58(2) Å). Its geometry remains practically unaffected by the complex formation (the Cr---Cr bond length in III and IV is 2.73(1) Å). The exchange parameter, −2J (410, 440 and 440 cm−1 in II to IV, respectively), also shifts only insignificantly from that of I, which probably means that indirect exchange via the sulphide bridge in I is of minor importance compared with the direct Cr---Cr exchange. The Cr---Cr bond length may thus be correlated with the observed overall exchange coupling. 相似文献