The complexes of tetramethylresorc[4]arene with amines. Effect of the amine concentration on the complex composition

The complexation of tetramethylresorc[4]arene with primary and secondary amines in acetonitrile was investigated spectrophotometrically. The stoichiometry of the complexes formed was shown to depend on the amine concentration. Based on the proposed complexation models, the formation constants of the complexes as well as their thermodynamical parameters were determined and discussed. Depending on the amine concentration, two types of solid complexes of tetramethylresorc[4]arene with amines were obtained. The composition of these complexes was confirmed by ¹H NMR.     

Raman spectra of olivine solid solutions (FexMg1−x )2SiO4 and spin-vibration interaction

Room temperature Raman spectra of synthesized powder (Fe_xMg_1?x )₂SiO₄ solid solutions are obtained. Frequency trend of all modes versus composition shows clearly the existence of a step at x = 0.3. A step-like behavior of vibration frequencies at the given composition that coincides with the percolation threshold for the olivine lattice is related to the appearance of magnetic excitations in the disordered magnetic medium owing to the spin-vibration interaction.     

NMR SPECTROSCOPIC STUDY ON COPOLYMER OF ETHYLENE-NORBORNENE

A series of ethylene-norbornene copolymers were synthesised using VO (OEt) Cl_2/Al_2Et_3Cl_3 catalytic system and their structure was characterized by ~1H-NMR, ~1H-~1HCOSY NMR and ~(13)C-NMR. Assignments of NMR spectra were given and discussed indetail.     

An experimental and theoretical study of the Cp2VO2CO: use of 13CO3(2-) for structure investigation of d1-metallocene complexes

EPR study has shown that the anticancer agent vanadocene dichloride (Cp2VCl2) interacts with carbonate contained in physiological solutions. Chelate complex Cp2VO2CO (|A(iso)(51V)| = 175.1 MHz, g(iso) = 1.9861) is the only paramagnetic species formed in the range about the physiological pH (5.5-11.0). The super-hyperfine coupling (|a(iso)(13C)| = 24.1 MHz) was evidenced at measurements using 13C labelled carbonate. The structure of carbonate complex was validated by comparison of observed and theoretical calculated HFC tensors (at the density functional level of theory).     

Impact of Transition Metal Substituents on Polysilane Properties: Iron versus Ruthenium

Summary. The previously unknown ruthenio disilanes Rp–Si₂Me₄–C₆H₄X (Rp = η⁵-C₅H₅Ru(CO)₂; X = H, Br, –CHO, CH=C(CN)₂) were synthesized from ClSi₂Me₄C₆H₄X (X = H, Br) and Rp⁻ using conventional chemical methods. Trends in the UV/Vis absorption spectra indicate strong electronic coupling within the Rp–Si–Si–C_aryl fragment and, therefore, closely resemble the ones observed for the corresponding iron complexes. The four compounds however, were shown to be less sensitive towards UV irradiation. The crystal structure of Rp–Si₂Me₄–C₆H₄CH=C(CN)₂ was determined by X-ray diffraction and exhibits an all-trans-array of the Ru–Si–Si–C_aryl moiety, what is a basic requirement for optimal through-bond interaction.     

纸带-光纤技术对硫化氢气体测量的初探

以研制的光导纤维反射分光光度计为仪器,建立了根据浸渍醋酸铅的纸带与硫化氢反应生成黑色硫化铅斑点而改变纸带相对反射率,达到对H2S测量的新方法。测量波长为450nm,测量H2S浓度范围为5×10-8mol/L～1.35×10-6mol/L。方法可用于测量废气中的硫化氢。     

膦、胂叶立德的化学与应用——Ⅰ.用红外光谱对膦、胂叶立德结构的研究

以78个带吸电子取代基的膦、胂叶立德的红外光谱的解析为根据,讨论了它们的结构及其与光谱的关系。     

Copper passivity and its breakdown in sodium bicarbonate solutions: A scanning electron microscopy and x-ray photoelectron and auger spectroscopy study

Effect of bicarbonate ions on the copper passivity and its local breakdown is studied by cyclic voltammetry, Auger spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. Comparing data for solutions with various sodium bicarbonate concentrations shows copper to undergo pitting in 0.02 M NaHCO₃, whereas it remains stably passive in 0.10 M NaHCO₃. Independent studies suggest that carbonates play a protective role in stabilization of the oxide-hydroxide passive film on copper.     

The alicyclic ring contraction of perfluoro-1-phenyltetralin in reaction with antimony pentafluoride

Perfluoro-1-phenyltetralin (1) heated with antimony pentafluoride at 130 °C, then treated with water, gave a mixture of perfluorinated 3-methyl-2-phenylindenone (3), 3-methyl-2-phenylindene (4), 3-hydroxy-1-methyl-3-phenylindan (5), 1-methyl-3-phenylindan (6), 9-methyl-1,2,3,4,5,6,7,8-octahydroanthracene (7), and 1,9-dimethyl-5,6,7,8-tetrahydro-β-naphthindan (8). When heated with SbF₅ in the presence of HF, then treated with water, compound 1 is transformed to a mixture of products 3-6. The reaction at 170 and 200 °C forms compounds 3-6 together with perfluoro-2-(cyclohexen-1-yl)-3-methylindene (10).     

Comparative EIS study of a paste electrode containing zinc powder in neutral and near neutral solutions

The corrosion and passivation of Zn powder particles dispersed in a paste electrode immersed in 0.5 M Na₂SO₄ and 5×10^–3 M Na₂HPO₄ solutions were studied mainly by electrochemical impedance spectroscopy. The role played by diffusion in the mechanism of anodic oxidation of zinc powder particles has been shown. It was demonstrated that the anodic reactionof Zn powder in neutral or near neutral media involves at least two adsorbed intermediates. By simulating the porous structure of the electrode, some information about porous nature of zinc electrode could be extracted. Electronic Publication