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41.
The reaction of cyclobutanone with an alkyne in the presence of a nickel(0) catalyst formally achieves intermolecular alkyne insertion between the carbonyl carbon and the α-carbon of a cyclobutanone, providing a six-membered carbocyclic skeleton. 相似文献
42.
《Analytica chimica acta》2002,459(2):229-234
The ligand 1,4,8-tri(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1) containing pendant octyl groups has been synthesised. L1 is a tetraazamacrocycle derived from the well-known cyclam unit, and the Ni2+ and Co2+ complexes, [Ni(L1)]2+ and [Co(L1)]2+, have been isolated and characterised. The ability of the nickel(II) and cobalt(II) complexes to act as anion receptors has been studied by using them as ionophores in membrane-based ion-selective electrodes (ISEs). The PVC membrane containing the complex [Ni(L1)]2+ and 2-nitrophenyloctylether as plasticizer shows a Nernstian response against iodide in a concentration range from 1×10−1 to 4×10−5 M I− with a detection limit of 1.6×10−5 M I− and a slope of 58.6 mV/pI− at pH 7 (25 °C). In comparison, the electrode containing [Co(L1)]2+ as ionophore gave a sub-Nernstian slope and a low lifetime. A comparison between the iodide-selective electrode containing [Ni(L1)]2+ and other reported iodide-selective electrodes is also reported. 相似文献
43.
The unseeded non-hydrolytic sol-gel synthesis of ZrW2O8 and ZrMo2O8 produces trigonal ZrM2O8 (M = W, Mo) at 740 and 300–400°C, respectively. Cubic ZrW2O8 can be prepared using non-hydrolytic sol-gel methods by seeding with small amounts of preprepared cubic material, and the formation of the trigonal polymorph can be suppressed completely. Seeds with a small particle size are necessary for the preparation of cubic ZrW2O8. In contrast, seeding of ZrMo2O8 gels with either cubic ZrMo2O8 or cubic ZrW2O8 only lowers the temperature at which the trigonal phase crystallizes. 相似文献
44.
The purpose of this study is to investigate the influence of nickel, which is an alloying element in commonly used metallic biomaterials, on the biomaterials mineralization process. An electrochemical method was developed to quantify this metal ion in osteoblast-like cell culture medium (OST) by performing adsorptive cathodic stripping voltammetry (CSV) with dimethylglyoxime (DMG) at a mercury film microelectrode (MFM). The optimized analytical conditions and the square-wave CSV parameters for the analysis are: DMG concentration: 5.00 × 10−4 mol L−1; ammonium chloride buffer: 0.10 mol L−1 (pH 9.2); frequency: 50 Hz, amplitude 20 mV; step: 2 mV; adsorption time: 10 s, deposition potential: −0.70 V and reduction potential: −1.20 V. The limit of detection was 7.70 × 10−9 mol L−1 for an adsorption time of 10 s. The results achieved by CSV using the MFM were compared to those obtained by atomic absorption spectrometry (AAS) to ensure the reliability of the electrochemical method. The mineralization process was evaluated by biochemical and histochemical assays. 相似文献
45.
Summary Nickel dithiocarbamate complexes derived from some sympathomimetic drugs are examined on silica Radial-Pak columns using binary solvents containing a small percentage of an organic polar modifier. Both the type and concentration of this modifier was found to influence the separation of the ternary from the parent binary complexes. When the two ligands in a ternary complex are racemic to each other, separation of the ternary complex is only possible when certain structural requirements of the molecule are fulfilled. Ternary complexes which contain structurally similar, but nonracemic ligands, are shown to be readily separated from binary complexes. When two such complexes differ only in that one of the ligands in one is enantiomeric to a ligand in the second complex, then it can be shown that the ternary complex with the (+) enantiomer ligand elutes faster from the silica column than the one with the (–) enantiomer ligand. An example of the use of ternary complexes for the identification of optical and structurally related impurities in pharmaceutical products is also given. 相似文献
46.
Chandra S Gupta LK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):1089-1094
Nickel(II) complexes, having the general composition Ni(L)2X2, have been synthesized [where L: isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and 4-aminoacetophenone thiosemicarbazone (LLD) and X=Cl-, 1/2SO(4)2-]. All the Ni(II) complexes reported here have been characterized by elemental analyses, magnetic moments, IR, electronic and mass spectral studies. All the complexes were found to have magnetic moments corresponding to two unpaired electrons. The possible geometries of the complexes were assigned on the basis of electronic and infrared spectral studies. Newly synthesized ligand and its nickel(II) complexes have been screened against different bacterial and fungal growth. 相似文献
47.
Nicole M. Brunkan 《Journal of organometallic chemistry》2003,683(1):77-82
The complex (dippe)Ni(η3-allyl)(CN) has been prepared and fully characterized (dippe=bis-(diisopropylphosphino)ethane), including X-ray diffraction studies, as a square pyramidal structure. The complex shows dynamic 1H-NMR behavior consistent with substantial structural rearrangements upon π to σ allyl interconversion. A comparison is made with (dippe)Ni(η3-allyl)Br, which also displays a square pyramidal structure. 相似文献
48.
《Journal of organometallic chemistry》1995,500(1-2):283-288
Reactions of -, β- and γ-hydrogen elimination in cyclopentadienylnickel compounds formed in the reactions of nickelocene with lithium or magnesium compounds are discussed. Elimination of -hydrogen from CpNiR where R is CH3, CH2C(CH3)3, CH2Si(CH3)3, CH2Ph or CH=C(CH3)2 leads to the formation of trinickel clusters (CpNi)3CR′, bis(cyclopentadienyl)(μ-cyclopentadiene)dinickel and (η5-cyclopentadienyl)(η3-cyclopenteny)nickel. β-hydrogen and γ-hydrogen elimination in vinylnickel compounds not possesing -hydrogen have been studied. Elimination and transfer of hydrogen forms (η3-allyl)(η5-cyclopentadienyl)nickel compounds. The mechanisms of these reactions are discussed. 相似文献
49.
We have determined the crystal structure of the title compound, which has a triclinic cell with cell parameters of , , , α=76.617°, β=84.188°, γ=74.510° and space group . The crystal structure suggests the chemical formula CoMoO4·3/4H2O. The structure consists of MoO4 tetrahedra and CoO6 octahedra, confirming the earlier X-ray absorption near-edge spectroscopic (XANES) investigation on the hydrate. The comparison of the crystal structures of the hydrate and the α-,β-, and hp-phases shows that the hydrate exhibits metal cation coordinations similar to those of the β-phase, but had arrangements of CoO6 and MoOn polyhedra similar to those of the hp-phase. 相似文献
50.
A practical speciation method for a solid mixture of nickel species applicable to atmospheric monitoring of Ni0, Ni2+ and NiOx is reported. This involves magnetic extraction of Ni0 to separate it from the water-soluble nickel salts and the insoluble oxides, followed by adsorptive stripping voltammetry to quantify the nickel in each fraction. The separation scheme was validated by using calibration standards and by simulating air-filter samples prepared with authentic nickel products. The recoveries of nickel were Ni0 94–105% and total nickel 95–102%. 相似文献