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31.
原子簇化合物的合成方法,由于条件限制,只有B、C、St等非金属元素与过渡金属袈基化合物等较为成熟.贵金属原子簇的合成则较困难.然而,应用激光等离子体反应,可使周期表内几乎所有元素都生成原子簇,为原子簇的生成与研究提供了一条新途径.该方法生成的原子簇在飞行时间质谱仪上可记录到一系列信号,某些信号呈现区域极大(或被称为‘匈数’吵].郑兰芬等用纯化的红磷粉分别与金粉、银粉混合,在激光等离子作源飞行时间质谱仪上得到一系列谱图【2]:ig与P作用只得到单核xg与P形成的lgy:iE离子簇.谱图较简单,*沪X最大可达叱叱… 相似文献
32.
The adsorption of the cationic dye acridine orange (AO) by different monoionic laponites leads to changes in the colloid properties of this synthetic mineral in aqueous solutions. The organic cation is adsorbed by the mechanism of cation exchange. Small amounts of adsorbed dye keep the clay in a peptized state with all metallic cations. Greater amounts of AO result in the neutralization of the electric charge of the clay, and its flocculation. In excess AO the charge of the clay platelets becomes positive and the clay is peptized. The colloid properties are studied by absorbance curves in which the absorbance is described as a function of the degree of saturation with constant clay concentrations or with constant dye concentrations. In the absorbance curves three regions can be identified. The transition between the first and second or the second and third regions depend on the exchangeable metallic cation initially present in the clay. The spectrophotometric method is useful in identifying the presence of tactoids and flocculation mechanism, whether it results in card-house or in book-house flocs. 相似文献
33.
Marina S. Fonari Victor Ch. Kravtsov Yurii A. Simonov Edward V. Ganin Vladimir O. Gelmboldt Janusz Lipowski 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(1-2):85-89
The crystalline host–guest type complex [(18-crown-6NH4)2][SiF6]4H2Ohas been obtained as the result of the interaction of SiF42NH3 with 18-crown-6 (18C6) in an aqueous medium. Crystal data: monoclinic, space groupC 2 c, a=26.541(2), b=8.363(2), c=20.469(2) Å, = 122.43(1)°and Z=4. The final R-value is 0.070 for 3253 reflections with I 2(I).The crystals consist of the complex [NH418C6]+ cations, [SiF6]2-anions and water molecules. The ammonium cation is hydrogen bonded by three of its H-atoms to the crown ether oxygen atoms with N(1) O separations2.923(5)–2.940(5) Å and by the fourth H-atom to the fluorine atom of thehexafluorosilicate anion, the N(1)F(4) distance being 2.797(6) Å.The conformation of the macrocycle and the hydrogen-bond geometry in thecomplex cation closely resemble those in related adducts between 18-crown-6and ammonium salts. All crystal components are connected via a system of hydrogen bonds into a ribbon along the b axis in the unit cell. 相似文献
34.
Makoto Minato Takefumi Kaneko Shogo Masauji Takashi Ito 《Journal of organometallic chemistry》2006,691(11):2483-2488
We describe the synthesis of a new asymmetric P,N,N′-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that [(η3-allylic)Pd(BPEMP)]+ complex forms only one isomer in the solid state as well as in solution. 相似文献
35.
E. I. Zhilyaeva S. A. Torunova R. N. Lyubovskaya R. B. Lyubovskii 《Russian Chemical Bulletin》1996,45(5):1107-1110
Radical cation salts with halide mercurate anions were obtained by the electrochemical oxidation of bis(ethylenedioxo)tetrathiafulvalene (BEDO-TTF), and their conductivity was studied. The compounds (BEDO-TTF)4Hg3X8 (X = Cl or Br), (BEDO-TTF)4Hg3.5I9, and (BEDO-TTF)2HgBr3 possess the conductivity of the metallic type down to helium temperatures.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1167–1170, May, 1996. 相似文献
36.
Paul D. Beer Zheng Chen Philip A. Gale Jennifer A. Heath Rachel J. Knubley Mark I. Ogden Michael G. B. Drew 《Journal of inclusion phenomena and macrocyclic chemistry》1994,19(1-4):343-359
The synthesis, metal, ammonium and alkyl ammonium cation coordination chemistry and electrochemical recognition studies of new diester-and diamide-calix[4]arenediquinone receptors are described. In addition the synthesis and coordination properties of a novel diamide benzo-15-crown-5-calix[4]arene molecule is reported.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes. 相似文献
37.
Geometry optimizations at the UHF/6-31G* and UMP2/6-31G* levels of theory were performed to find the transition state in the interconversion between norbornadiene (N) and quadricyclane (Q) radical cations. Two transition structures, TS+·1 and TS+·2, were obtained which have C1 and C2 symmetry, respectively. Vibrational analysis at the UHF and UMP2 levels of theory and IRC calculation showed that TS+·1 is the true transition state connecting N+· and Q+·, while TS+·2 is a second order saddle point. 相似文献
38.
Jan S. Jaworski 《Monatshefte für Chemie / Chemical Monthly》1984,115(4):415-418
A two parameter approach to solvent variations in the electroreduction rate constants of cobalt complexes and europium cations is presented and discussed in terms of solvent—solute and solvent—solvent interactions.
Ein Zwei-Parameter Donor-Acceptor-Ansatz für Lösungsmitteleffekte bei der Elektrodenkinetik von Kationen (Kurze Mitteilung)
Zusammenfassung Es wird eine Zwei-Parameter-Annäherung der Lösungsmitteleinflüsse auf die Geschwindigkeitskonstanten der Elektroreduktion von Kobalt-Komplexen und Europium-Kationen präsentiert und auf der Basis von Lösungsmittel—gelöster Stoff- und Lösungsmittel—Lösungsmittel-Wechselwirkung diskutiert.相似文献
39.
The reaction paths for the transformations of substituted acetylenes (X—CC—Y; X, Y = H, Me, Ph, CN) in reaction with phenylsulfenium cation were studied by quantum-chemical methods. It was shown that the reactions take place with the formation of acyclic and cyclic cationic intermediates. The factor that determines the structure and characteristics of these cations is the induction and polarizing action of the substituents in the acetylenes and to a lesser degree their electron-donor characteristics. The resonance effect of the phenyl substituent has a predominantly levelling action on the distribution of charges. 相似文献
40.
Teng-Kuei Yang Dong-Sheng Lee Tsung-Fan Teng Ting-Ting Jong Mei-Yueh Chien 《中国化学会会志》1991,38(4):401-403
Introducing two chiral auxiliaries, sulfoxide and menthol, into an acrylate would have either matched or mismatched pair systems. The presence of chiral menthol in α-sulfinylacrylates can change the diastereoselectivity from 24% d.e. to a single diastereomer by manipulation of the double asymmetric strategy. 相似文献