1,721,099 research outputs found
Synthesis and X-ray crystal structure of the novel organotin dication [n-Bu2Sn(H2O)4]2+: A lamellar layered structure assisted by intermolecular hydrogen bonding
No full textThe reaction of n-Bu2SnO with 2,5-dimethylbenzenesulfonic acid affords the stable monomeric tin complex [n-Bu2Sn(H2O)4]2+[2,5-Me2 -C6H3SO3]2-. The solid-state structure of the molecule reveals that the hydrogen-bonding interaction between the coordinated water and the sulfonate anion moieties leads to an unprecedented two-dimensional layered structure with a planar array of tin atoms. Further, the Lewis acidic dication complex is an extremely good catalyst for acylation of alcohols and phenols
First example of a Sn-C bond cleaved product in the reaction of Ph3SnOSnPh3 with carboxylic acids. 3D-Supramolecular network formation in the X-ray crystal structure of [Ph2Sn(OH)OC(O)(Rf)]2, Rf = 2,4,6-(CF3)3C6H2
No full textA 1∶2 reaction of Ph3SnOSnPh3 1 with RfCOOH 2 leads to the formation of [Ph2Sn(OH)OC(O)(Rf)]2 3, by means of a facile Sn-C bond cleavage process. © 2003 Royal Society of Chemistry
Reactions of n-Bu2SnO and (n-Bu3Sn)2O with 1,1,2,3,3-Pentamethyltrimethylene Phosphinic Acid: Synthesis and X-ray Crystal Structures of a Novel Spirocyclic Coordination Polymer and a 16-Membered Inorganic Macrocycle
No full textSynthesis of a tetranuclear organooxotin cage by debenzylation reactions: X-ray crystal structure of [(PhCH2)2Sn2O(O2P(OH)-t-Bu)4 ]2
No full textThe reactions of (PhCH2)2SnCl2, (PhCH2)2SnO·H2O, and (PhCH2)3SnCl with 2 equiv of t-BuP(O)(OH)2 afford the tetranuclear organooxotin cage [(PhCH2)2Sn2O(O2P(OH)-t-Bu)4 ]2 (4) in good yields. The formation of the half-cage intermediate [(PhCH2)2Sn2O(O2P(OH)-t-Bu)4 ] (4a) en route to 4 has been detected by 119Sn and 31P NMR. The molecular structure of compound 4 as determined by single-crystal X-ray analysis shows a tetranuclear cage structure containing two Sn-O-Sn motifs connected by bridging [t-BuP(OH)(O)2]- ligands. The solid-state structure of 4 is retained in solution
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
Cyclophosphazene supramolecular assemblies: N-H⋯N and C-H⋯N mediated supramolecular networks in the crystal structures of N 3P3[N(Me)NH2]6 and spiro-N 3P3 [O2C12H8][N(Me) NH2]4
No full textCyclophosphazene hydrazides, N3P3[N(Me) NH2](6) 1 and spiro-N3P3[O2C12H8][N(Me)NH2](4) 2 have been found to organize themselves in supramolecular assemblies in the solid state. Thus, 1 forms a hexagonal close-packed sheet in which each molecule interacts with its six nearest neighbors. All the three ring nitrogen atoms act as proton acceptors while one N(Me) NH2 substituent on each phosphorus atom acts as a proton donor. Compound 2 forms a double chain in which two ring nitrogen atoms act as proton acceptors and one N( Me) NH2 substituent of each phosphorus atom acts as a proton donor. The supramolecular assembly of 1 is further elaborated by intermolecular C-H...N interactions
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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