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81.
Bis-paddlewheel heterobimetallic complexes in which palladium(II) is connected to the rare-earth metals(III) [Pd(μ-OOCMe)4Ln(OH2)(μ,η2-OOCMe)]2 × 2HOOCMe (Ln = Nd, Sm, Eu, Yb and Tm) by four acetate bridges were synthesised by the reaction of Pd3(μ-OOCMe)6 with the LnIII acetates. The tetraacetate-bridged complexes were unexpectedly found to be readily transformed by the stoichiometric amount of pivalic acid into the mono-paddlewheel tetrapivalate-bridged analogues in which the paddlewheel structure [Pd(μ-OOCR)4Ln] maintains as established by X-ray crystallography. The role of the intra- and intermolecular H-bonding in these complexes is discussed. 相似文献
82.
The reaction of 2-substituted cyclopropane-1,1-dicarboxylates with 1- and 2-pyrazolines is efficiently catalyzed by scandium or ytterbium triflates to give N-substituted 2-pyrazolines or 1,2-diazabicyclo[3.3.0]octanes. The reactions of 2-pyrazolines give diazabicyclooctanes as the major products. In contrast, the reactions starting from 1-pyrazolines predominantly give N-substituted 2-pyrazolines, which become the major compounds obtained if an equimolar amount of GaCl3 is used. A possible reaction mechanism is suggested. 相似文献
83.
The reactions of aluminum carbenoids with alkyl- and phenyl-substituted allenes and cyclic allenes are studied. An efficient method for the synthesis of substituted spiropentanes was developed. 1,2-Cyclononadiene was selectively converted into bicyclo[7.1.0]dec-1-ene. An unusual transformation of α-methylphenylallene into a spiroindane derivative under the action of Et3Al-CH2I2 was found. 相似文献
84.
Triethylamine reacts with aqueous zinc acetate and the product of its thermolysis in the presence of benzoic acid to yield
the complexes [Zn7(μ4-O)(μ-OOCMe)10][η-OC(Me)OHNEt3]2 (1) and [Zn2(μOOCPh)4][η-OC(Me)OHNEt3]2 (2), respectively. The reactions of 1 and 2 with 3,5-dimethylpyrazole at room temperature in benzene yield pyrazolate-bridged binuclear complexes Zn2(μdmpz)2(Hdmpz)2(OOCR)2 (R = Me (3), Ph (4)). The structures of complexes 1–4 have been determined by X-ray crystallography. 相似文献
85.
R. A. Novikov D. N. Platonov V. A. Dokichev Yu. V. Tomilov O. M. Nefedov 《Russian Chemical Bulletin》2010,59(5):984-990
1,3-Dipolar cycloaddition reaction of diazo esters to electron-deficient dipolarophiles to yield the corresponding 1- or 2-pyrazolines
was found to be significantly accelerated with Lewis acids (Yb(OTf)3, Sc(OTf)3, GaCl3, EtAlCl2). The use of GaCl3 as the catalyst leads to the acceleration not only of the 1,3-dipolar cycloaddition reaction, but also subsequent insertion
of the CHCO2Me electrophilic fragment of methyl diazoacetate into the N-H bond of 2-pyrazolines formed. Such Lewis acids as SnCl4, BF3, TiCl4, and In(OTf)3 are not efficient in the described processes, since they rapidly decompose starting diazo compounds. 相似文献
86.
Yu. V. Tomilov D. N. Platonov G. P. Okonnishnikova O. M. Nefedov 《Russian Chemical Bulletin》2010,59(7):1387-1392
Thermal decomposition of N-substituted hepta(methoxycarbonyl)-3a,7a-dihydroindazoles proceeds through the elimination of hexamethyl benzenehexacarboxylate
and results in the generation of l-aryl-3-methoxycarbonylnitrile imines, which are intercepted by both the electron-withdrawing
and electron-releasing olefins, for example, methyl acrylate, cyclopentene, vinylcyclopropane, or ethyl vinyl ether, to form
the corresponding pyrazolines and pyrazoles. In the presence of propan-2-ol, the main process proceeds through the addition
of nitrile inline to the O—H bond to form methyl 2-isopropoxy-2-[2-(4-methoxyphenyl)hydrazono]acetate. 相似文献
87.
Asymptotic approximation of the moving spike-type contrast structure in reaction-diffusion equations
The asymptotic approximation of a moving spike-type contrast structure for the reaction-diffusion equation is constructed.
The results were applied for an important case of cubic nonlinearity. 相似文献
88.
Detailed calculations of eigenmodes of waveguiding structures made of silver and glass and containing coaxial cables with
a nanoscale cross section of different configurations are conducted. In particular, the study focuses on optical coaxial waveguides
with the core made in the form of a thin metallic cylinder filled with a dielectric. We show that these waveguides support
relatively low-loss propagation of radiation that is strongly localized in the central region, has phase velocity approaching
the speed of light and predominant electric-field orientation (dipole type). Optical characteristics of such waveguides are
compared with those of coaxial-type waveguides containing a continuous central filament made of metal and with a multilayer
structure. Using numeric modeling, we established that the proposed type of the waveguide enables the transmission of an optical
image with relatively low losses with a submicron resolution over a distance considerably longer than its cross section. A
typical propagation length in the waveguides based on silver and glass with the refractive index of about 1.5 at a wavelength
of 500 nm is about 1700 nm. 相似文献
89.
90.