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401.
402.
José V. Folgado Emilio Escrivá Aurelio Beltrán-Porter Daniel Beltrán-Porter 《Transition Metal Chemistry》1987,12(4):306-310
Summary Dimeric and polymeric copper(II) complexes containing BPCA (N-2-pyridinylcarbonyl-2-pyridinecarboximidate), having general formulae Cu(BPCA)X·nH2O (X=Cl, Br, NCS, NCO, N3, or CN) and Cu2(BPCA)2-X·nH2O [X=oxalate anion (OX), chloranilate anion (CA) or the dianion of 2,5-dihydroxy-1,4-benzoquinone (DHBQ)] have been synthesized by the copper(II)-assisted hydrolysis of 2, 4, 6-tris(2-pyridyl)-1, 3, 5-triazine. Spectroscopic results indicate five-coordinate, approximately square-pyramidal, geometry around the copper(II) ion. Half-field absorption in the M
s=±2 region of the X-band e.p.r. powder spectra has been observed for the dimeric species. 相似文献
403.
Reaction of bicyclophosphane with glycol , glycerol , erythritol , L(-)arabitol and dulcitol leads to the corresponding per-alkoxybicyclophosphoranes - which are in tautomeric equilibrium with the phosphates forms ′ - ′.The amount of these latters increases regularly from traces to 24%. 相似文献
404.
Abdelouahad El-Himri Pedro Núñez Fernando Sapiña Aurelio Beltrán 《Journal of solid state chemistry》2004,177(7):2423-2431
Interstitial molybdenum-tungsten, vanadium-tungsten and vanadium-molybdenum-tungsten oxynitrides in the solid solution series Mo1−zWz(OxNy) and V1−zWz(OxNy) (z=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1), and V1−u−zMouWz(OxNy) (u, z=0.2, 0.33, 0.4, 0.6; u+z<1), have been obtained by ammonolysis of precursors resulting from the freeze-drying of aqueous solutions of the metal salts (NH4VO3, (NH4)6Mo7O24·4H2O and (NH4)6W12O39·18H2O). A study of the influence of the preparative variables on the outcomes of this procedure is presented. Compounds in the Mo1−zWz(OxNy) series are prepared as single phases by ammonolysis of the respective freeze-dried precursors (during 2 h) at different temperatures between 973 and 1023 K, optimised for each composition, followed by slow cooling of the samples (except for the Mo-only containing phase, in which fast cooling has been used). Compounds in the V1−zWz(OxNy) and V1−u−zMouWz(OxNy) series are prepared as single phases by ammonolysis (during 2 h) of crystalline precursors (as resulting from thermal treatment in air at 873 K, during 12 h, of the freeze-dried precursors) at 1073 K, followed by slow cooling of the samples. All the compounds in these series have the rock-salt crystal structure, in which the metal atoms are in an fcc arrangement, with non-metal atoms occupying octahedral interstitial positions. The materials have been characterized by X-ray powder diffraction, elemental analysis, scanning electron microscopy and magnetic measurements. 相似文献
405.
Chanh Bui Cong Georges Gence Bernard Garrigues Max Koenig Aurelio Munoz 《Tetrahedron》1979,35(15):1825-1839
An equilibrium occurs between penta- and hexacoordinated phosphorus when a basic function is located at the end of a branched ligand on pentacoordinate phosphorus. Generally the hexacoordinated form are thermodynamic stable species in solution at room temperature. Eight hexacoordinated compounds (9–11, 13, 14, 18–20, Tables 2 and 3) have been isolated. In few cases, in solution, the pentacoordinated form (15–17, 24) can be observed. The parameters from these equilibria are discussed. 相似文献
406.
This paper deals with the main statistical results obtained through Sirio after two years of activity. They concern absolute attenuation at 11.6 and 17.8 GHz, and differential attenuation over a bandwidth of 500 MHz centered around 11.6 GHz. Long-term statistical relationships between the attenuation at the various frequencies, and fade duration and gradients, are presented. Preliminary rain-intensity measurements collected at the same sites are also reported in order to assess the climatological effects of the different locations in which data have been collected. 相似文献
407.
408.
Gervais C Profeta M Lafond V Bonhomme C Azaïs T Mutin H Pickard CJ Mauri F Babonneau F 《Magnetic resonance in chemistry : MRC》2004,42(5):445-452
1H, 13C, 17O and 31P NMR parameters, including chemical shift tensors and quadrupolar parameters for 17O, were calculated for phenylphosphonic acid, C6H5PO(OH)2, under periodic boundary conditions. The results are in very good agreement with experimental data and permit the unambiguous assignment of all the sites present in the structure. In particular, the 17O NMR parameters of the P=O and P-OH environments were precisely determined, which should help in the characterization of the bonding mode of phosphonate molecules in hybrid solids. Moreover, the effect of intermolecular interactions on the NMR parameters were investigated by comparing the results of the calculations in the crystal and in an isolated molecule of phenylphosphonic acid. 相似文献
409.
A new route using very mild reaction conditions is described for the transformation of indoloquinolizidines
and
to the 1-oxo-1,2,3,4-tetrahydro-β-carbolines
and 相似文献
410.
Basilico F Sauerwein W Pozzi F Wittig A Moss R Mauri PL 《Journal of mass spectrometry : JMS》2005,40(12):1546-1549
Boron neutron capture therapy (BNCT) is a promising binary treatment for cancer. BNCT is based on the ability of the nonradioactive isotope (10)B to capture, with a very high probability, thermal neutrons. This nuclear reaction results in two particles (an alpha and a lithium nucleus). The particles have a high biological effectiveness, which is limited in tissue to approximately the diameter of one cell. If the reaction can be limited to a tumor cell, the physical characteristic opens up the possibility to selectively destroy cancer cells, while sparing the surrounding healthy tissue. Quality control of (10)B-containing compounds and their distribution at present are very important, and different analytical methods have been developed, such as time-of-flight secondary ion mass spectrometry (TOF-SIMS), electron energy loss spectrometry (EELS), prompt gamma analysis and inductively coupled plasma-optical emission spectrometry (ICP-OES). These methods allow the analyses of (10)B, but it is not possible to characterize the specific molecular compounds containing (10)B. For this reason, we propose a fast and quantitative method that permits the determination of closo-undecahydro-1-mercaptododecaborate (BSH) and (10)boron-phenylalanine (BPA) and their eventual metabolites. In particular, (10)B-containing compounds are detected by means of flow-injection electrospray tandem mass spectrometry (FI/ESI-MS/MS). This approach allows the identification of Boron compounds, BSH and BPA, using tandem mass spectrometry, and quantitative analysis is also possible (c.v. +/-4.7%; n = 5; linear range 10-10,000 ng/ml). Furthermore, (10)B-containing compounds were detected in actual biological sample (urine and plasma, diluted 10,000- and 1,000-fold, respectively) injecting a small volume (1 microl) of diluted samples. 相似文献