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61.
Photo-extrusion of nitrogen from the azoalkane 1 in the presence of molecular oxygen gave besides the hydrocarbons 3 and 5, the endoperoxide 10 and hydroperoxide 11, the former via trapping of the 1,4-diradical 4 by triplet oxygen, the latter by ene-reaction-6f hydrocarbon 5 with singlet oxygen. 相似文献
62.
S.I. Pombrik D.N. Kravtsov B.A. Kvasov E.I. Fedin 《Journal of organometallic chemistry》1977,136(2):185-200
A 19F NMR study of the transmission of electronic effects has been made for the systems Ar2EC6H4F-4 (E = Sb, Bi, CH, N). The fluorine chemical shifts obtained are correlated with the polar constants (Σσo and Σσ) of the substituents, suggesting that electronic effects are transmitted through the SbCar, BiCar and CCar bonds predominantly by an inductive mechanism, whereas the transmission through the NCar bonds is contributed to significantly by classical resonance effects due to competitive conjugation of the lone pair with the aromatic rings, and the substituents therein. A dual parameter correlation of the fluorine chemical shifts with the inductive (σI) and resonance (σoR and σR) parameters of the substituents in the aromatic rings has led to similar conclusions. The inductive transmission through the bridging Sb and Bi atoms has been assigned to the absence of conjugation of lone pair and vacant d-orbitals of the metals with π-electron systems of the aromatic rings. On the basis of the values of the ? coefficients for the correlation equations obtained it has been established that the transmitting ability of the BiCar bonds is close to that of the CalCar bonds and considerably lower than the transmitting ability of the NCar bonds. 相似文献
63.
William H. McCarroll Cynthia Darling Gary Jakubicki 《Journal of solid state chemistry》1983,48(2):189-195
Fused salt electrolysis has been used to prepare a number of reduced oxides of molybdenum with lanthanum, neodymium, and yttrium in single crystal or oriented polycrystalline form. The average valence of molybdenum in the various compounds ranged from 5.67 to 3.50. Previously unreported compounds include La5Mo4O16 (triclinica = 5.64 Å,b = 20.7 0Å,c = 5.64 Å, α = 86.55°, β = 90.0°, γ = 93.45°); La2Mo2O7 (orthorhombic,a = 12.19 Å,b = 6.05 Å,c = 3.87 Å); LaMo2O5 (hexagonal,a = 8.378 Å,c = 19.26 Å). In addition, single crystal specimens have been prepared of Y2MoO5,Ln5Mo3O16(Ln =La, Nd) and metal atom cluster compounds of theA2Mo3O8 type (A = Mg, Co, Ni, Zn). 相似文献
64.
Roger N. F. Thorneley 《Journal of organometallic chemistry》1974,70(3):C37-C39
The kinetic isotope effect for β-hydride elimination from alkyliridium(I) complexes has bee found to be kH/kD = 2.28 ± 0.20. 相似文献
65.
The rates of cleavage of some XC6H4CH2SnMe3 bonds by aqueous-methanolic perchloric acid have been measured spectrophotometrically, and the rate of cleavage of the MeSn bonds of PhCH2SnMe3 and Me4Sn by monitoring the methane evolution. The results indicate that for X = H, p-Me, o-Me, p-But, o-, m- and p-F and -Cl, and o-Br, the cleavage of the CH2SnMe3 bond involves attack of the acid at the benzylic atom, and is not much faster than that of the SnMe bonds, but that a mechanism involving ring-protonation is important for X = m-Me, and greatly predominant for X = m-OMe. 相似文献
66.
Oxygen reduction on immersed gold electrodes has been studied in Li2CO3 melt under steady-state conditions and by the potential-sweep method. Reaction order measurements have established that the species being reduced is not molecular oxygen, but the peroxide ion. The latter is in chemical equilibrium with molecular oxygen and oxide ions. The rate-determining step is the primary charge transfer where (O?) is a transient species. The exchange current densities and activation energies have been determined. Under conditions where O22? diffusion is not limiting (e.g. meniscus electrodes) the rate of neutralization of oxide by CO2 at the electrode surface is probably rate-determining. 相似文献
67.
The proton NMR spectra of N-[2-pyridyl-N-oxide]-derivatives of primary and secondary ethylamines, containing a substituent R on the C atom bearing the amino function, have been completely analysed in terms of the fundamental NMR parameters. The preferred conformations of the compounds investigated were established by the indications from NOE experiments as well as: (1) the long range coupling across the five bond between the aminic hydrogen and the proton in 4-position of the pyridine-N-oxide ring (5JmH,NH ~ 0·5 c/s), (2) the value of the vicinal coupling constant in the fragment CHNH (3JNHCH ~ 7–9 c/s), (3) the large deshielding (Δτ ~ 1–1·5 ppm) observed for the resonance position of the proton on the asymmetric C atom in secondary amine derivatives with respect to the corresponding primary ones, and (4) the diamagnetic shielding produced on protons in position 3 and 4 of the pyridine-N-oxide ring by different aromatic groups introduced in the R substituent.The NMR data confirmed the preferred rotamers previously suggested on the basis of ORD and CD measurements. 相似文献
68.
A high-powered, microwave-induced nitrogen–oxygen plasma (N2–O2–MIP) generated by using an Okamoto cavity at atmospheric pressure was investigated when the observation height, the flow rate of carrier gas, and the oxygen content were varied as the experimental parameters. The emission characteristics of the plasma were evaluated with regard to the excitation temperature and the intensity ratio of atomic line to ionic line. The excitation temperature of the N2–O2–MIP was in the range of 5100–5700 K when the oxygen content was varied from 0 to 30% at the observation height of 7 mm and the carrier gas flow rate of 0.6 l/min. The intensity ratio of atomic line to ionic line was elevated with an increase in the oxygen content. 相似文献
69.
Yoshihiko Ito Yoshinori Inubushi Toru Sugaya Takeo Saegusa 《Journal of organometallic chemistry》1977,137(1):1-9
Reaction of carboxamides with Cu2O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu2Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu2Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described. 相似文献
70.
The mercury(II)-catalysed replacement of cyanide in hexacyanoferrate(II) by p-nitrosodiphenylamine (p-NDA) in aqueous solution has been investigated spectrophotometrically by measuring the change in absorbance of the green complex ion, [Fe(CN)(5).p-NDA](3-), at 640 nm. Activation parameters of the catalysed and uncatalysed reactions have been calculated. The effects of the dielectric constant and water content of the medium on reaction rates are used to explain the formation of a polar activated complex and suggest an I(d) mechanism for the catalysed reaction. The varying catalytic activity of Hg(II) as a function of concentration has been discussed. 相似文献