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TRANS-2-STYRYLBENZOTHIAZOLE COMPLEXES WITH MERCURY(II) HALIDES - SYNTHESIS, CHARACTERIZATION AND X-RAY CRYSTAL-STRUCTURE OF DIIODOBIS(TRANS-2-STYRYLBENZOTHIAZOLE)MERCURY(II)
No full textThe synthesis of trans-2-styrylbenzothiazole (L) and of its complexes with mercury(II) halides is reported. Complexes with the formulae [Hg2(L)Cl4], [Hg(L)Br2], [Hg(L)2I2] and [Hg(L)I2] were isolated and characterized by conventional chemical analysis, electronic and IR spectra and by thermal analysis. For one of these complexes, [Hg(L)2I2], the X-ray crystal structure was also determined. The complex consists of discrete [Hg(L)2I2] units in which mercury, located on a two-fold axis, shows a distorted tetrahedral coordination and the ligand molecules are bonded via nitrogen atoms with Hg-I = 2.61(2) angstrom and Hg-N = 2.36(1) angstrom bond distances
POLYNUCLEAR CHLOROCADMATE(II) COMPOUNDS WITH RIBBON-LIKE STRUCTURES - SYNTHESIS, STRUCTURAL CHARACTERIZATION AND THERMAL-BEHAVIOR
No full textIn this paper we report the synthesis and the structural characterization of two polynuclear chlorocadmate(II) systems with ribbon-like structure of formula (H(2)eten)[Cd2Cl6] . H2O (H(2)eten = ethylethylenediamine dication) and (Hetpipd)(2)[Cd5Cl12(H2O)(2)] . H2O (Hetpipd = 1-ethylpiperidine cation), respectively. (H(2)eten)[Cd2Cl6] . H2O crystallizes in space group P2(1)/a. The unit cell dimensions are a = 16.910(2), b = 13.570(2), c = 6.701(3) Angstrom, beta = 94.93(2)degrees, V = 1532(1) Angstrom(3), Z = 4. The final R value is 0.029 (R(w) = 0.028). Its structure consists of organic dications, polymeric ribbons formed by two infinite zig-zag chains running along the z axis linked by a common edge between adjacent octahedra and uncoordinated water molecules. The (Hetpipd)(2)[Cd5Cl12(H2O)(2)] . H2O crystallizes in space group C2/c. The unit cell dimensions are a = 26.811(2), b = 6.643(3), c = 21.724(2) Angstrom, beta = 111.25(3)degrees, V = 3606(2) Angstrom(3), Z = 4. The final R value is 0.039 (R(w) = 0.045). Its structure consists of alternate trinuclear [Cd3Cl6(H2O)(2)] and dinuclear [Cd2Cl6](2-) units, forming polymeric ribbons, organic cations and uncoordinated water molecules. Both packings are strengthened by hydrogen-bond interactions between anions and cations. The thermal properties for both compounds are discussed
STRUCTURAL, THERMAL, AND ELECTRICAL CHARACTERIZATION OF BIS(ETHYLETHYLENE)DIAMMONIUM DICHLORIDE TETRACHLOROCADMATE(II) WITH PEROVSKITE-LIKE STRUCTURE
No full textThe synthesis, thermal and electrical characterization of a chlorocadmate(II) system with perovskite-like structure of formula (etenH-2)2[CdCl4].Cl2 (etenH-2 = ethylethylenediamine dication) are described. The compound crystallizes in space group P2(1)/c. The unit-cell dimensions are a = 19.214(1) angstrom, b = 7.301(1) angstrom, c = 7.227(3) angstrom, beta = 100.23(1)-degrees, V = 997.7(4) angstrom3, Z = 2. The final R value is 0.0486 (R(w) = 0.0497). The crystal structure consists of inorganic layers of (CdCl6) corner-sharing octahedra, organic dications intercalated between them and uncoordinated chloride ions. Only one end of the organic dications interact via hydrogen bonds with the inorganic layers, with the second end involved in hydrogen bonds with the free chloride ions. Furthermore a network of hydrogen bond interactions among the inorganic layers, the organic dications, and the uncoordinated chlorine atoms contribute to the crystal packing. The compound, thermally stable up to the melting point, behaves as an electrical insulator at low temperatures, approaching semiconductor values at higher ones
Asymmetric reduction of (4S)-(+)-carvone catalyzed by enoate reductases (ERs) expressed by non-conventional yeast (NCY) whole-cells.
No full textSYNTHESIS AND CHARACTERIZATION OF ONE-DIMENSIONAL POLYMERIC CHLOROCADMATE(II) SYSTEMS
No full textIn this paper we report the synthesis and the structural, thermal, electrical properties of 1-D polymeric chlorocadmates(II), having N-methylpropane-1,3-diammonium (mepnH2) and NN-diethylpropane-1,3-diammonium (et2pnH-2) as countercations. The (mepnH2)2[Cd3CI10] crystallizes in space group P2(1)/c. The unit cell dimensions are a = 10.164 (3) angstrom, b = 13.434 (10) angstrom, c = 10.099 (3) angstrom, beta = 112.04 (3)-degrees, V = 1278 (i) angstrom3, z = 2. The final R value for 2124 reflections (I > 2sigma(I)) is 0.0445 (R(w) = 0.0384). Its structure consists of N-methylpropane-1,3-diamine dications and infinite chains of [(Cd3Cl10)n4n-]n moieties forming 1-D polymer running along the x axis. The (et2pnH2)2[Cd5Cl14].2H2O crystallizes in space group P1BAR. The unit cell dimensions are a = 6.874 (1) angstrom, b = 10.381 (1) angstrom, c = 14.572 (i) angstrom, a = 100.14 (1)-degrees, beta = 99.31 (1)-degrees, gamma = 97.46 (1)-degrees, V = 996.7 (2) angstrom3, Z = 1. The final R value for 3405 reflections (I > 2sigma(I)) is 0.0452 (R(w) = 0.0393). Its structure consists of N,N-diethylpropane-1,3-diamine dications, infinite alternate stacked pseudoplanar trinuclear [Cd3Cl8]2- and dinuclear [Cd2Cl6]2- dianions and uncoordinated water molecules. Both the packings are strengthened by N-H ... Cl hydrogen bonds between anions and cations. A first-order phase transition of (mepnH2)2[Cd3CI10] has been identified by DSC measurements and X-ray powder diffraction, related to the disordering of the hydrocarbon chains at high temperature. This increases the cell volume. The electrical conductivity of the compounds can be envisaged as protonic, and the whole electrical behavior can be correlated to their structures and phase transition
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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