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[Pd(-NaiR)(O,O)] [-NaiR = 1-alkyl-2-(naphthyl--azo)imidazoles; R = Me (a), Et (b), CH2Ph (c) and O,O = pyrocatecholato (cat) (3), 4-t-butylcatecholato (tbcat) (4), 3,5-di-t-butylcatecholato (dtbcat) (5), and tetracholorocatecholato (tccat) (6)] complexes were characterized by elemental analyses, i.r. and 1H-n.m.r. spectral data. Studies by cyclic voltammetry suggest the existence of two redox couples, positive saturated calomel electrode (s.c.e.) that are due to catecholes to semiquinone, and semiquinone to quinone oxidations, respectively; two couples at negative to s.c.e. are associated with azo reductions. The complexes exhibit ligand-to-ligand charge-transfer transition in the near-i.r. region. The band position is largely dependent upon the substituent on the catechole frame and exhibits a negative solvatochromic effect. The transition is qualitatively assigned to the HOMO (cat) LUMO (-NaiR) transition. 相似文献
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Rauth Goutam Kumar Dinda Joydev Jasimuddin Sk. Sinha Chittaranjan 《Transition Metal Chemistry》2003,28(1):88-95
1-Alkyl-2-(naphthyl--azo)imidazoles [-NaiR; R = Me (a), Et (b), CH2Ph (c)] react with Pd(MeCN)2Cl2 to yield Pd(-NaiR)Cl2
(2), the i.r. spectra of which support the presence of a cis-PdCl2 configuration. The complexes react with catechols in the presence of Et3N to yield ternary complexes [Pd(-NaiR)(O,O)] [O,O = pyrocatecholato (cat) (3), 4-t-butylcatecholato (tbcat) (4), 3,5-di-t-butylcatecholato (dtbcat) (5), and tetrachlorocatecholato (tccat) (6)], which were characterized by elemental analysis, i.r. and 1H-n.m.r. spectral data. Redox studies by cyclic voltammetry suggest the existence of four successive redox couples wherein two responses, positive to s.c.e. are due to catechol to semiquinone and semiquinone to quinone oxidation, respectively; the couples at negative to s.c.e. are referred to azo reductions. The complexes exhibit ligand-ligand charge-transfer transitions in the near-i.r. region. The band position is largely dependent upon the substitutent on the catechol frame and exhibits negative solvatochromic effects. The transition is qualitatively assigned as the HOMO (cat) LUMO (-NaiR) transition. This fact is also supported by theoretical calculations using the PM3 method. 相似文献
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G. Schulze O. Elsholz R. Hielscher A. Rauth S. Recknagel und A. Thiele 《Fresenius' Journal of Analytical Chemistry》1989,334(1):9-12
Summary The German standard method for the determination of chloride in water, waste water and sludge, laid down in the norm DIN 38405-D 1–2, is based on the titration with AgNO3 and potentiometric detection for the range 7–140 mg/l chloride. In order to investigate the equivalence of a more rapid method, flow injection analysis with different detection methods (photometric, potentiometric and by atomic absorption) is applied. Thirty samples of water of different types (waste, tap, surface and mineral water) are analysed and the results are examined by a statistical test, which, according to the norm DIN 38402, part 71, is based on orthogonal regression. The test shows that the results obtained with the FIA-methods are equivalent to those from the German standard method. The three flow injection systems mentioned have a 10–36-fold higher sample frequency and a lower (down to 1/1000) sample and reagent consumption. Therefore, these FIA-methods are superior to the actual German standard method. 相似文献
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Rauth Goutam K. Maity Subrata Sinha Chittaranjan Mahapatra Ambikesh 《Transition Metal Chemistry》2003,28(5):518-524
Nucleophilic substitutions of Pd(N,N)Cl2[(N,N = 1-methyl-2-(arylazo)imidazole (RaaiMe), p-RC6H4N=NC3H2NN-1-Me; 2-(arylazo)pyridine (Raap), p-RC6H4N=NC5H4N; 2-(arylazo)pyrimidine (Raapm), p-RC6H4N=NC4H3N2 where R = H (a), Me (b), Cl (c)] with 8-quinolinol (HQ) have been examined by spectrophotometry at 298 K in MeCN solution. The product, Pd(Q)2, has also been confirmed by independent synthesis from Na2[PdCl4] and HQ in EtOH. The kinetics of the reaction have been studied under pseudo-first-order conditions and the analyses support a nucleophilic association path. A single phase reaction has been observed and follows the rate law, rate = a + k [Pd(N,N)Cl2] [HQ]2. Thus, the reaction is first order in [Pd(N,N)Cl2] and second order in [HQ]. External addition of Cl–(LiCl) suppresses the rate. The rate increases as follows: Pd(RaaiMe)Cl2 < Pd(Raap)Cl2 < Pd(Raapm)Cl2. 相似文献
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M. Block D. Ackermann K. Blaum A. Chaudhuri Z. Di S. Eliseev R. Ferrer D. Habs F. Herfurth F. P. Heßberger S. Hofmann H.-J. Kluge G. Maero A. Martín G. Marx M. Mazzocco M. Mukherjee J. B. Neumayr W. R. Plaß W. Quint S. Rahaman C. Rauth D. Rodríguez C. Scheidenberger L. Schweikhard P. G. Thirolf G. Vorobjev C. Weber 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(1):39-45
The Penning-trap mass spectrometer SHIPTRAP allows precision mass
measurements of rare isotopes produced in fusion-evaporation reactions. In
the first period of operation the masses of more than 50 neutron-deficient
radionuclides have been measured.
In this paper the perspectives for direct mass measurements
of rare isotopes around nobelium are discussed and the achievable precision is addressed.
The temporal stability of the magnetic field, an important issue for the long
measurement times resulting from the low production rates, was investigated and the
time-dependent uncertainty due to magnetic field fluctuations was determined.
Based on the present performance direct mass measurements of nobelium isotopes are
already feasible. With several technical improvements heavier elements between Z=102–105 will be in reach. 相似文献
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A. Martın D. Ackermann G. Audi K. Blaum M. Block A. Chaudhuri Z. Di S. Eliseev R. Ferrer D. Habs F. Herfurth F. P. Heßberger S. Hofmann H. -J. Kluge M. Mazzocco M. Mukherjee J. B. Neumayr Yu. Novikov W. Plaß S. Rahaman C. Rauth D. Rodrıguez C. Scheidenberger L. Schweikhard P. G. Thirolf G. Vorobjev C. Weber 《The European Physical Journal A - Hadrons and Nuclei》2007,34(4):341-348
Direct mass measurements of nuclides near to the supposed end-point region of the astrophysical rp-process were performed
at SHIPTRAP, the Penning trap mass spectrometer at GSI Darmstadt. The masses of 24 nuclides were measured with relative uncertainties
between 5 . 10-8 and 2 . 10-7 . Three of them, 107Sb , 111I and 112I , were determined experimentally for the first time. The data analysis and mass evaluation are presented in detail. 相似文献
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G. Walder D. Margreiter C. Winkler V. Grill T. Rauth P. Scheier A. Stamatovic Z. Herman M. Foltin T. D. Märk 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,20(1):201-203
Stoichiometric and non-stoichiometric, positive and negative oxygen cluster ions (n up to 70) have been produced in a crossed neutral beam/electron beam ion source. The abundance and stability of the ions formed have been analyzed with a double focussing sector field mass spectrometer in a series of experiments. Positive and negative ion mass spectra observed exhibit distinct abundance anomalies, however, at different cluster sizes. Abundance maxima and minima correlate with correspondingly small and large metastable fractions of (O2) n + and (O2) n ? ions, respectively. (O2) n + ions may also lose up top=(n?1) monomers by collision induced dissociation with monotonously decreasing probability with increasingp. Metastable fractions determined for (O2) n ? ions produced with appr. zero eV electrons are in general larger than those for ions produced with appr. 7 eV electrons. (O2) n ? ions are also observed to decay via autodetachment, with lifetimes increasing with increasing cluster size. Finally, here we were able to prove that an apparent loss of the monomer fragment O (and higher homologues) observed in the metastable time regime is due to ordinary metastable monomer evaporation in the acceleration region. Moreover, we will also present here some new data and interpretation concerning the electron attachment cross section function for O2 clusters. 相似文献