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THE REACTION OF HEXACARBONYLVANADIUM WITH AROMATIC-COMPOUNDS .4. PROPERTIES OF TETRACARBONYLVANADIUM ARENE CATIONS AND THE CRYSTAL AND MOLECULAR-STRUCTURE OF TETRACARBONYL(1,2,4,5-TETRAMETHYLBENZENE)VANADIUM(I) HEXACARBONYLVANADATE(1-)
No full textImproved syntheses of the cationic arene complexes of vanadium( I), [V( C0)4(CsHs-nMen)+] ,a re reported
together with their 1 H n.m.r. spectra. An X-ray crystal and molecular structure determination of the
title compound has been carried out. Crystals are monoclinic, space group P&/a, a = 18.135(5),
& = 12.746(4), c = 10.025(4) A, Q = 93.03(2)",a nd Z = 4. R = 0.072 for 1 007 observed
reflections (Mo-K, radiation). In the cation the vanadium atom is half-sandwiched between the
arene ligand and the four carbonyl groups, the tatter being oriented in such a way as to become eclipsed
with respect to two of the methyl groups. The [V(CO)s]- anion is a nearly regular octahedron with a
mean V-C distance of 1.93 A and two sets of C-V-C angles, thus leading to a slight trigonal
elongation of the octahedron
REDOX REACTIONS INVOLVING HEXACARBONYLVANADIUM(0) AND COMPOUNDS CONTAINING ELEMENT HALIDE, ELEMENT HYDROGEN AND ELEMENT CARBON BONDS - SYNTHESIS, AND CRYSTAL AND MOLECULAR-STRUCTURE OF PH3PBV(CO)6
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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
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
Synthesis of tricarbonyl derivatives of rhenium(I) with Group 16 donor atoms. Crystal and molecular structure of di-mu-bromo-mu-1,8-naphthalenedisulfide-bis(fac-tricarbonylrhenium(I))
No full textThe tetrahydrofuran adduct Re2Br2(CO)(6)(THF)(2) reacts with 1,8-naphthalenedisulfide (NDS) to give Re2Br2(CO)(6)(NDS), which crystallizes in the monoclinic system, space group P2(1)/c, with cell constants a=10.071(4), b=21.229(5), c=10.135(7) Angstrom; beta=105.73(5)degrees, and Z=4 molecules per unit cell. The final R value is 0.044 for 2035 data (Mo-K-alpha). The Re2Br2(CO)(6) fragment is the same as in all previously determined structures of this series, having bridging bromides and a fac tricarbonyl arrangement about each rhenium atom. The rhenium atoms are also bridged by the disulfide fragment of NDS forming two five-membered rings of composition Re-S-S-Re-Br. The fold angle across the Br ... Br vector is 29 degrees. The Re-Br distances are unequal, with the shorter distances to the bromine closer to the naphthalene fragment; this bromine is further from the S-S bridge than the other. The Re-S and S-C distances average 2.48 and 1.78 Angstrom, respectively, while the S-S bond is 2.16 Angstrom long. Both the Re-S-S-Re and C-S-S-C torsion angles are nearly 0 degrees, which is a significant distinction from the previously investigated structures of this type. The NDS ligand is significantly non-planar, and this may be due to steric repulsion from the nearby carbonyl groups. The dibenzyldisulfide and dibenzyldiselenide complexes Re-2(mu-I)(2)(CO)(6)(E(2)Bz(2)), E=S, Se, have been prepared starting from the same THF rhenium(I) precursor. The Se NMR data of the dibenzyldiselenide complex show a downfield shift of about 165 ppm with respect to the uncomplexed molecule under the same conditions. Bis(dimethylphosphine)ethane gives ReI(CO)(3)(Me(2)PCH(2)CH(2)PMe(2)); iodide abstraction from the latter by silver triflate gave Re(SO3CF3)(CO)(3)(Me(2)PCH(2)CH(2)PMe(2)), which is suggested to contain the monodentate triflato ligand
Carbonyl Derivatives of Phthalocyaninatoiron((II), Expecially those Containing Group 6 Axial Donor Atoms. Crystal and Molecular Structure of (N,N-Dimethylformamido)Carbonyl-Pthalocyaninatoiron(II) and Mössbauer Spectra of Some of the Products,
No full textReaction of a tetranuclear N,N-di-iso-propylcarbamato complex of cerium(III) with dioxygen: synthesis and X-ray characterization of both the oxidation product and its precursor
No full textABSTRACT The tetranuclear N,N-di-iso-propylcarbamato complex of cerium(III) Ce-4((O2CNPr2)-Pr-i)(12), 1, has been synthesized and its crystal structure solved through X-ray diffraction methods. The oxidation of the cerium(Ill) complex by dioxygen produces the mu(3)-OXO tetranuclear cerium(IV) derivative Ce-4(mu(3)-O)(2)((O2CNPr2)-Pr-i)(12), 2, which has been characterised by single crystal X-ray diffractometry. Structural rearrangements on going from the cerium(111) derivative to the corresponding cerium(IV) product have been established. This is the first case of a mu-oxo-carbamato complex being obtained by oxygenation, whereby product and precursor maintain the basic structural features
Bis-Adducts of Phthalocyaninatoiron(II) with Group 6 Donor Atoms. Crystal and Molecular Structure of Bis(Dimethylsulphoxide) Phthalocyaninatoiron(II), DMSO Solvated
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