1,721,049 research outputs found
Structural and theoretical studies of mono and di-insertion of symmetric alkynes into the Pd–C σ bond of cyclopalladated secondary (tert-butyl and ethyl) benzylamines
No full textThe reactivity of the dinuclear cyclopalladated complexes derived from secondary benzylamines,
[Pd2{(C,N)eC6H4CH2NH(R)}2(m-X)2] [X 1⁄4 Br, R 1⁄4 t-Bu (1a); X 1⁄4 Cl, R 1⁄4 t-Bu (1b); X 1⁄4 Cl, R 1⁄4 Et (1c)] is
reported. 1a reacted with dimethyl acetylenedicarboxylate (DMAD) to yield the mono-inserted complex
[Pd2{(C,N)eC(CO2Me)]C(CO2Me)C6H4CH2NH(t-Bu)}2(m-Br)2] (2a). 1a, 1b and 1c reacted with (R0)
C^C(R0) (R01⁄4 CO2Me, Ph) to give [Pd{(C,N) C(R0)]C(R0)C(R0)]C(R0)C6H4CH2NH(R)}X] [X 1⁄4 Br, R 1⁄4 t-Bu,
R01⁄4 CO2Me (3a); X 1⁄4 Cl, R 1⁄4 t-Bu, R01⁄4 Ph (2b); X 1⁄4 Cl, R 1⁄4 Et, R01⁄4 Ph (2c)] through a double insertion of
the alkyne into the PdeC s bond. 2c also reacts with Ag(CF3SO3) and pyridine to give mononuclear
cationic complex [Pd{(C,N)eC(Ph)]C(Ph)C(Ph)]C(Ph)}C6H4CH2NH(Et)(py)]CF3SO3 (3c). The crystal
structures of di-inserted complexes 2b, 2c and 3c have been determined by X-ray diffraction studies.
Their molecular structures showed that the conformation of the C]C double bonds within the buta-
dienyl group attached to the aromatic ring was transecis. Density functional theory (DFT) calculations
also indicated that this arrangement is more stable than other possible conformations
Crystal structure of the 1:1 complex between the cis-anti-cis- isomer of dicyclohexano-18-crown-6 and 6-chloro-7-sulphamido-3, 4-dihydro-1, 2, 4-benzo-thiadiazine-1, 1-dioxide
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
CCDC 1014981: Experimental Crystal Structure Determination
No full textRelated Article: Ali Akbar Khandar, Farhad Akbari Afkhami, Seyed Abolfazl Hosseini-Yazdi, Jonathan M. White, Scott Kassel, William G. Dougherty, Janusz Lipkowski, Donald Van Derveer, Gerald Giester, Ferdinando Costantino|2015|Inorg.Chim.Acta|427|87|doi:10.1016/j.ica.2014.11.028,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
UNUSUAL PROPERTIES OF WATER
No full textWater has been known for its unusual properties from antiquity when, e.g. was found that hot water freezes faster than cold water. Presently, on the web page 'water' Martin Chaplin [1] lists sixty seven properties of water which may be considered 'anomalous' when comparing to 'normal' chemical substances. Much of this can be attributed to the spatial structure of hydrogen bonding in condensed phases of water. Hydrogen bonding constitutes about 2/3 of cohesion energy of water. However, the remaining 1/3 is definitely not negligible. Combination of the two leads to properties of water in the systems where it plays a role. The very comprehensive range of such systems and common presence of water make the enormous variety of structures and properties of water-containing compounds. In the present paper the non-hydrophilic component of properties of water will be emphasized in combination with the structural aspects of supramolecular bonding of water molecules
Anion influence in the structural diversity of cadmium coordination polymers constructed from a pyridine based Schiff base ligand
No full textA series of seven coordination polymers based on Cd and potentially tetradentate pyridine based Schiff
base ligand with different anions (CH3COO, NO2
, Cl, I, N3
, SCN), [Cd(L)(CH3COO)(OH2)]n (1),{[Cd2
(L)2(NO2)2(CH3OH)2]CH3OH}n (2), {[Cd2(L)2Cl2(CH3OH)2]CH3OH}n (3), [Cd(HL)I2]n (4), [Cd3(L)2(N3)4]n
(5), [Cd(L)(SCN)(OH2)]n (6) and [Cd(HL)(SCN)2]n (7) {HL = 2-pyridinecarbaldehyde isonicotinoyl hydrazone
(HPCIH)} in order to rationalize the effect of the anion, have been synthesized and characterized
by elemental analyses, FT-IR spectroscopy, single crystal X-ray data diffraction, etc. The results show
the influence of the counter-ions on the coordination mode of the cadmium ion that is capable of forming
compounds with five-, six- and seven-coordination numbers. The ligand acts as a negatively charged tetradentate
N3O-donor ligand and coordinates to the cadmium center in the enolic form (@NAN@CAO) in
1–3 and 5–6 while in compounds 4 and 7 coordinates as N3- and N3O-donor neutral ligand in keto form
(@NANHAC@O), respectively. Cadmium centers in 1–4 and 6, bridging by the HPCIH ligand cause to form
one-dimensional coordination polymers and the anions act as terminal ligands. In compounds 5 and 7,
the N3
and SCN also act as bridging ligands to the metal centers, and form 3D and 2D metal–organic
polymers respectively.
2014 E
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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