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71.
Saeki N Nakamura N Ishibashi T Arime M Sekiya H Ishihara K Matsumoto K 《Journal of the American Chemical Society》2003,125(12):3605-3616
Reactions of the head-to-head 2-pyridonato-bridged cis-diammineplatinum(III) dinuclear complex having nonequivalent two platinum atoms, Pt(N(2)O(2)) and Pt(N(4)), with p-styrenesulfonate, 2-methyl-2-propene-1-sulfonate, 4-penten-1-ol, and 4-pentyn-1-ol were studied kinetically. Under the pseudo first-order reaction conditions that the concentration of the Pt(III) dinuclear complex is much smaller than that of olefin, a consecutive basically four-step reaction was observed: the olefin pi-coordinates preferentially to the Pt(N(2)O(2)) in the first step (step 1), followed by the second pi-coordination of another olefin molecule to the Pt(N(4)) (step 2). In the next step (step 3), the nucleophilic attack of water to the coordinated olefin triggers the pi-sigma bond conversion on the Pt(N(2)O(2)), and the second pi-bonding olefin molecule on the Pt(N(4)) is released. Finally, reductive elimination occurs to the alkyl group on the Pt(N(2)O(2)) to produce the alkyl compound (step 4). The first water substitution with olefin (step 1) occurs to the diaqua and aquahydroxo forms of the complex, whereas the second substitution (step 2) proceeds either on the coordinated OH(-) on the Pt(N(4)) (path a) or on the coordinatively unsaturated five-coordinate intermediate of the Pt(N(4)) (path b), in addition to the common substitution of H(2)O (path c). The reactions of p-styrenesulfonate and 2-methyl-2-propene-1-sulfonate proceed through paths b and c, whereas the reactions of 4-penten-1-ol and 4-pentyn-1-ol proceed through paths a and c. This difference reflects the difference of the trans effect and/or trans influence of the pi-coordinated olefins on the Pt(N(2)O(2)). The pentacoordinate state in path b is employed only by the sulfo-olefins, because these exert stronger trans effect. The steps 3 and 4 reflect the effect of the axial alkyl ligand (R) on the charge localization (R-Pt(IV)(N(2)O(2))-Pt(II)(N(4))) and delocalization (R-Pt(III)(N(2)O(2))-Pt(III)(N(4))-OH(2)); when R is p-styrenesulfonate having an electron withdrawing group, the charge localization in the dimer is less pronounced and the water molecule on the Pt(N(4)) atom is retained (R-Pt(III)(N(2)O(2))-Pt(III)(N(4))-OH(2)) in the intermediate state. In both routes, the alkyl group undergoes nucleophilic attack of water, and the oxidized products are released via reductive elimination. 相似文献
72.
Oxidation of allyl-substituted allene episulfides with a peracid gave the corresponding allene episulfide S-oxides which were found to undergo ready isomerization to bicyclo[2.1.1]thiahexane S-oxide derivatives on thermolysis or under acid-catalyzed reaction conditions. 相似文献
73.
74.
Yuji Iijima Yasushi Kamei Nami Kobayashi Junji Awaka Taku Iwasa Shuji Ebisu 《哲学杂志》2013,93(21):2521-2530
A new thiospinel CuCrZrS4 has been successfully synthesized by a solid-state chemical reaction. This CuCrZrS4 exhibits ferromagnetic properties below the Curie temperature at T c = 60 -2 K. The appearance of irreversible effect between field-cooled and zero-field-cooled magnetization is prominent below around 5 K in a magnetic field of less than 150 Oe. The ac susceptibility χAC shows a rapid decrease below about 10 K. This low magnetic-field behaviour indicates the existence of a re-entrant spin-glass phase below about 10 K. The dc magnetic susceptibility above 100 K shows Curie-Weiss behaviour with an effective magnetic moment of 3.61 μ B, which is a little less than the spin-only value of 3.87 μ B for the Cr3+ ion. The asymptotic Curie temperature θ P is approximately 65 K, which is a little higher than T c. The valence state is confirmed to be Cu+Cr3+Zr4+S4 2? on the basis of magnetic properties. The electrical resistivity ρ shows a semiconducting temperature dependence over the temperature range from 4.2 to 280 K with an activation energy of 6.84 210?3 eV in the higher temperature range from 50 to 283 K. 相似文献
75.
Hikaru Takano Tetsuo Narumi Nami Ohashi Akinobu Suzuki Toshiaki Furuta Wataru Nomura Hirokazu Tamamura 《Tetrahedron》2014
A significant substitution effect of the position of the bromo group on the photosensitivity of the 8-azacoumarin chromophore leads to the development of a highly photosensitive 8-aza-3-bromo-7-hydroxycoumarin-4-ylmethyl (aza-3-Bhc) group that shows excellent photolytic efficiency and hydrophilicity with long-wavelength absorption maxima. The newly identified aza-3-Bhc group can be applied to caged glutamates for ester-type and carbamate-type protections of carboxyl and amino functionalities. 相似文献
76.
The propagation of bulk waves in rectangular nanoplates is studied on the basis of nonlocal three-dimensional elasticity theory. The nonlocal theory applies to both thin and thick rectangular orthotropic nanoplates. The dispersion relation for the waves is derived analytically. Our results are checked against data for macroplates. The influence of nonlocality and other parameters on the wave frequency and phase velocity is discussed. 相似文献
77.
J. Tashkhourian S. F. Nami Ana S. Hashemnia M. R. Hormozi-Nezhad 《Journal of Solid State Electrochemistry》2013,17(1):157-165
A modified carbon paste electrode was prepared by incorporating the TiO2 nanoparticles in the carbon paste matrix. The electrochemical behavior of gallic acid (GA) is investigated on the surface of the electrode using cyclic voltammetry and differential pulse voltammetry. The surface morphology of the prepared electrode was characterized using the scanning electron microscopy. The results indicate that the electrochemical response of GA is improved significantly at the modified electrode compared with the unmodified electrode. Furthermore, the capabilities of electron transfer on these two electrodes were also investigated by electrochemical impedance spectroscopy. Under the optimized condition, a linear dynamic range of 2.5?×?10?6 to 1.5?×?10?4?mol?L?1 with detection limit of 9.4?×?10?7?mol?L?1 for GA is obtained in buffered solutions with pH 1.7. Finally, the proposed modified electrode was successfully used in real sample analysis. 相似文献
78.
Heidar Raissi Azadeh Khanmohammadi Mehdi Yoosefian Fariba Mollania 《Structural chemistry》2013,24(4):1121-1133
In the current study, we present an intramolecular HB, molecular structure, π-electrons delocalization and vibrational frequencies analysis of 25 possible conformers of 1-(thionitrosomethylene) hydrazine by means of DFT (B3LYP), MP2 methods in conjunction with the 6-311++G** and augmented correlation-consistent polarized-valence triple-zeta basis sets and G2MP2 theoretical level. The influence of the solvent on the stability order of conformers and the strength of intramolecular hydrogen-bonding was considered using the Tomasi’s polarized continuum model. Statistical analyses of quantitative definitions of aromaticity, nucleus independent chemical shift, harmonic oscillator model of aromaticity, aromatic fluctuation index, and the π-electron delocalization parameter (Q) as a geometrical indicator of a local aromaticity, evaluated for this conformers. Further verification of the obtained transition state structures were implemented via intrinsic reaction coordinate (IRC) analysis. Calculations of the 1H NMR chemical shift at GIAO/B3LYP/6-311++G** levels of theory are also presented. The calculated highest occupied molecular orbital (MO) and lowest unoccupied MO energies show that charge transfer occur within the molecule. Hydrogen-bond energies for H-bonded conformers were obtained from Espinosa method and the natural bond orbital theory and the atoms in molecules theory were also applied to get a more precise insight into the nature of such H-bond interactions. 相似文献
79.
Mahboob Alam Shahab A.A. Nami Ahmad Husain Dong-Ung Lee Soonheum Park 《Comptes Rendus Chimie》2013,16(3):201-206
The synthesis, spectral characterization, crystal structure and antimicrobial activity of the novel synthetic molecule 7a-Aza-B-homostigmast-5-eno [7a,7-d] tetrazole, C29H48N4 has been reported. The structure has also been determined by X-ray diffraction technique using direct method and was refined on F2 by the full-matrix least-squares. Crystals are orthorhombic and their space group is P212121, with a = 7.230(3), b = 31.451(13), c = 11.974(5) (Å), α = β = γ = 90°. It can be conveniently obtained by the reaction of 7-Oxostigmast-5-ene with hydrazoic acid. The molecule has also been screened for its possible in vitro antimicrobial activity against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyogenes, Staphylococcus epidermidis, Bacillus cereus, Corynebacterium xerosis, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa (MTCC 424). Minimum inhibitory concentration (MIC) of the synthesized compound has also been evaluated. The highest activity is observed against C. xerosi and P. vulgaris. Moreover, the compound has also been screened for its in vitro cytotoxicity against human colon carcinoma cell line, HCT116 and human liver hepatocellular carcinoma cell line, HepG2, using doxorubicin as standard. On the basis of its IC50 values, 7a-Aza-B-homostigmast-5-eno [7a,7-d] tetrazole was found to inhibit the cancer cells effectively. 相似文献
80.
Mehdi D. Esrafili Fariba Mohammadian-Sabet Mohammad Solimannejad 《Structural chemistry》2014,25(4):1197-1205
Ab initio calculations were performed to investigate the cooperativity between the S···N(C) bond and the hydrogen/lithium/halogen bond interactions in O2S···NCX···NCH and O2S···CNX···CNH triads (X=H, Li, Cl, and Br). To understand the properties of the systems better, the corresponding dyads are also studied. It is evident that the lithium bond has a bigger influence on the chalcogen bond than vice versa. The results indicate that the enhanced interaction energies of the S···N(C) and X···N(C) interactions in the triad increase in the order NCCl < NCBr < NCH < NCLi and CNCl < CNBr < CNH < CNLi. This is the order of the increasing positive electrostatic potential V S,max on the X atom. The nature of S···N(C) and X···N(C) interactions of the complexes is unveiled by energy decomposition analysis and natural bond orbital (NBO) theory. The cooperativity between both types of interaction is chiefly caused by the electrostatic effects. 相似文献