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Structure of catena–(2–Amino–1,3,4–Thiadiazolium, 2–Amino–1,3,4–Thiadiazole bis(mu–Iodo)–di–Iodo–Bismuth(III))
No full text[(C2H4N3S) (C2H3N3S) BiI4]infinity; [(HL) (L) BiI4]infinity (L = 2-amino-1,3,4-thiadiazole), M(r) = 919.86, monoclinic, P 1 2(1)/a 1, a = 7.622(1), b = 18.977(2), c = 12.821(1)angstrom, beta = 102.77(1)-degrees, final R = 0.033. The crystals consist of HL+ cations, neutral L molecules and polymeric [BiI4]infinity- anions built up of edge-sharing [BiI6]3- octahedra, with Bi-I(bridging) distances in the range 3.320(1)-3.057(1) angstrom and Bi-I(terminal) distances in the range 2.917(1)-2.929(1)angstrom. The H-1 and C-13 spectra in DMSO-d6 solution are used in conjunction with the X-Ray structural results to establish the preferred protonation site of the thiadiazole ring
Synthesis, Crystal and Molecular Structure, and Infrared Characterization of Two Amino Derivatives of 1,3,4–Thiadiazole
No full text2-Amino-5-methyl-1,3,4-thiadiazole, 2-amino-5-methyl-3H-1,3,4-thiadiazolium bromide [(amtzH)(amtz)Br] and bis(2,5-diamino-3H-1,3,4-thiadiazolium) sulfate [(a2tzH)2SO4] were prepd. and characterized by x-ray structural anal. and IR spectroscopy. The crystals of (amtzH)(amtz)Br are monoclinic. Its asym. unit contains one protonated amtzH cation, one neutral amtz mol., and one bromide ion. The crystals of (a2tzH)2SO4 are monoclinic. The structure is built up of one crystallog. independent a2tzH cation and one half sulfate ion with crystallog. dictated twofold symmetry
Antimony and bismuth trihalide complexes of dithiomalonamide, N,N'-dimethyl- and N,N'-diphenyl-dithiomalonamide.
No full textSome antimony and bismuth trihalide complexes of dithiomalonamide and its N,N’-alkyl and aryl derivatives have been isolated. The ligands were S,S-coordinated to the metal. Two IR bands due to M-S vibrations and some mass-dependent bands assignable to M-X modes were observe
Modulated Magnetic Coupling in Alkoxoiron(III) Rings by Host-guest Interactions with Alkali Metal Cations
No full textTwo novel host-guest complexes of alkali-metal ions with cyclic iron(III) clusters, [LiFe6(OCH3)12(dbm)6]X (X = PF6-, ClO4-; Hdbm = dibenzoylmethane), were synthesized. The x-ray structure of [LiFe6(OCH3)12(dbm)6]PF6 ([1]PF6) is described and compared with that of sodium complexes, previously reported. [1]PF6.1/2CHCl3.9MeOH crystallizes in trigonal space-group R-3 with (at 298 K) a = 14.523(2) Å, α = 84.35(1), V = 3021.3(7) Å3 and Z = 1. The radius of the encapsulated alkali-metal ion has a marked influence on the geometry of the [Fe6(OCH3)12] host. Substitution of sodium with lithium decreases nearest-neighbor Fe···Fe sepns. and Fe-O-Fe angles, while it does not affect Fe-O distances. A quant. anal. of the magnetic susceptibility of solid samples revealed that weaker Fe-Fe antiferromagnetic interactions occur in the lithium complexes. The authors suggest that host-guest interactions modulate the magnetic coupling by detg. the exact geometry at the bridging methoxide ligands. 7Li and 23Na NMR expts. have beautifully illustrated the soln. behavior of the reported complexes and the selectivity of six-membered iron(II) rings for alkali-metal ions. The structural and functional analogy between iron(III) rings and crown ethers is stressed
Polyiron(III)–Alkoxo clusters: a Novel Trinuclear Complex and Its Relevance to the Extended Lattices of Iron Oxides and Hydroxides
No full textThe synthesis, solid-state structure and magnetic characterization of KFe3(OMe)7(dbm)3·4MeOH (I; Hdbm = dibenzoylmethane) are reported. I readily assembles in methanolic solns. of Fe(III) chloride and Hdbm in the presence of an excess of K methoxide; it crystallizes in the triclinic space group P-1 with a = 13.044(1), b = 14.174(1), c = 18.657(2) Å, α = 97.94(1), β = 104.13(1), γ = 114.12(1)°, and Z = 2 at 190 K, R = 0.046 and Rw = 0.051. The solid-state mol. structure of I consists of a triangular array of Fe(III) ions connected by a triply bridging methoxide and three μ2-methoxide ligands. The O donors of a monodentate methoxide and of a chelating dbm ligand complete the coordination sphere of each metal ion. The resulting mononeg. Fe3(μ3-OMe)(μ2-OMe)3(OMe)3(dbm)3 moiety coordinates the K counterion through the oxygens of the μ2-OMe ligands. The O atoms in the core of I are arranged in two essentially parallel layers and display a closest-packing which is found in Fe oxides and hydroxides. The high-spin Fe(III) ions are antiferromagnetically coupled with an S = 1/2 spin ground state. Assumption of a C2v point-group symmetry for the cluster leads to a satisfactory reprodn. of the obsd. magnetic behavior with g = 2.0 and either J = 10.6(1), J' = 15.3(2) cm-1 or J = 12.9(2), J' = 9.7(1) cm-1, where the spin-only Heisenberg Hamiltonian is defined as H = .sum.i>jJijSi·Sj and J' is the unique coupling const. The relative contributions of geometrical distortions and of antisym. exchange to the splitting of the 4-fold 2E electronic ground state of an idealized system with trigonal symmetry were estd. from X-band EPR spectra recorded on powd. samples
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
Manganese(III) Formate: A Three-dimensional Framework that Traps Carbon Dioxide Molecules
No full textThe reaction of KMnO4 with 95% formic acid led to the formation of "manganese(III) formate" of compn. Mn(HCOO)3·1/2CO2·1/4HCOOH·2/3H2O, which was characterized spectroscopically, by TGA, and by x-ray crystallog. (cubic, space group Im-3, R1 = 0.0520). The structure of "manganese(III) formate" is a three-dimensional framework of manganese ions bridged by six nearest formate ligands, and the resulting open cages trap carbon dioxide and formic acid mols. Jahn-Teller distortion of the MnIII ions was shown by the magnetic properties, which also indicated ferromagnetic intralayer and weaker antiferromagnetic interlayer interactions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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