51 resultados para structure based alignments


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An unusual composite hybrid material [Co-4 (phen)(8) (H2O)(2) (HPO3)(2)](H3O)(3) [PMo8VI V-4(IV) O-40 ((VO)-O-IV) 2] 1 (phen = 1,10-phenanthroline) has been hydrothermally synthesized from a mixture of NH4VO3, Na2MoO4.2H(2)O, CoCl2.6H(2)O, phen, H3PO3 and water. It was characterized by elemental analysis, IR, UV-vis, XPS, EPR, TG and single crystal X-ray diffraction. The title compound is constructed from the organic-inorganic hybrid [Co-4(phen)(8)(H2O)(2) (HPO3)(2)](4+) and highly reduced bi-capped pseudo-Keggin [(PMo8V4O40)-V-VI-O-IV ((VO)-O-IV)(2)](7-) polyoxoanions The structure exhibits an extended 2D network through hydrogen bonds among cations, anions and H2O, combining polyoxometalates with metal phosphonates for the first time.

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A charge transfer salt, (Bu4N)(4) (C5H6)[(HSiMo11MoO40)-Mo-VI-O-V] has been photochemically synthesized from (Bu4N)(4)SiMo12O40 and 1.3-cyclopentadiene and Characterized, by elemental analysis, IR spectra, solid diffusion reflectance electronic spectra, CV and ESR. The X-ray crystal structure revealed that the title complex crystal data are as follows: triclinic, space group P (1) over bar, a = 14.347(3), b = 14.423(3), c = 27.158(5) Angstrom, alpha = 96.90(3), beta = 104.18(3), gamma = 98.20(3)degrees, V = 5322(2) Angstrom (3), Z = 2, M-r = 2855. 30, D-c = 1.782g.cm(-3), F(000) = 2860, R = 0.0719, wR = 0.198. The title compound is composed of 1.3-cyclopentadiene, four tetrabutylammonium and [(SiMo11MoO40)-Mo-VI-O-V](4-) anion.

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By electrocrystallization of 2,6-[4,5-bis(n-butylsulfanyl)-1,3-dithiol-2-ylidene]-4,8-bis(6-iodo-n-hexyloxy)-1,3,5,7-tetrathia-s-indacene (BHBDTI) and [NBu4](4)[SiMo12O40] in the mixed solvent CHCl2CH2Cl and CH3CN, the new radical-ion salt [C42H60Cl2O2S12](2)[SiMo12O40] was prepared. It was characterized by means of IR and ESR spectroscopy and X-ray diffraction. In the crystal structure, organic radical dications and silicomolybdate anions are alternatively arranged along the a axis to form a 1-D conducting layer. The organic layer consists of two isolated groups of BHBDTI divided by the (011) plane without short interatomic contacts. However, in each group, BHBDTI molecules associate with each other in a head to tail manner running along the [011] direction and face-to-face overlapping with a relative shift by approximately one TTF subunit along the long axis of the molecule and a slight shift along the short axis of the molecule with significantly short S ... S contacts. The room-temperature d.c. conductivity determined by the two-probe method is 10(-4) S cm(-1), suggesting that the compound is a semiconductor.

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The polycrystalline powder of the cyclic tetramer based on bisphenol A and o-phthaloyldichloride has been prepared by recrystallization from nitrobenzene and its crystal structure has been determined by Wide-Angle X-ray Diffraction (WAXD). The unit cell is orthorhombic and its dimensions a = 0.967 6 nm, b = 0.869 9 nm, c = 2.085 9 nm, Space group belongs to Pmmm, With two tetramers per unit cell,the crystal density is 1.36 g . cm(-3), Indices of crystal diffraction peaks are also detailed in the present work.

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The polycrystalline powder of the cyclic tetramer ester based on bisphenol-A and o-phthaloyldichloride has been prepared by recrystallization from nitrobenzene and its crystal structure determined by wide-angle X-ray diffraction. The unit cell is orthorhombic and has dimensions a=0.967 nm, b=0.8699 nm, c = 2.0859 nm. With two tetramers per unit cell, the crystal density is 1.36 g cm(-3). Indices of crystal diffraction peaks are also detailed in the present work. Copyright (C) 1996 Elsevier Science Ltd.

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The mixed oxides LaNiO3, La0.1Sr0.9NiO3, La2NiO4 and LaSrNiO4 with perovskite (ABO(3)) and related(A(2)BO(4)) structures were prepared and the adsorption property for NO and the catalytic activity for NO decomposition over these oxidse were also tested. The catalysts were characterized by means of BET surface measurement, chemical analysis, NO-TPD etc.. It was shown that the adsorption amount of NO is correlated with the concentration of oxygen vacancy formed and the adsorption type and strength of NO are related to the valence of metallic ion. Generally there are three kinds of adsorption species, NO-, NO+ and NO on the mixed oxides, among them the negative adsorpion species (NO-) are active for NO decomposition. The weaker the adsorption of oxygen on the catalyst is, the faster the mobility of oxygen is and the easier the redox process takes place in reproducing the active sites in which the oxygen species (O-, O2-) would participate.