1,720,973 research outputs found
Control strategies for error handling in a knowledge-based system for image processing and recognition
No full textDonor Substituted Cyclopenta Benzo-fused Congeners as Versatile Ligands
No full textRecently we focused our attention on the chemistry of hydroxy functionalised π-extended ring systems (1). These ligands have been obtained by one-step nucleophilic addition reaction of cyclopentadienyl or the benzo-condensed homologues indenyl and fluorenyl anions on substituted oxirane, as propylene (CH2CHMe)O and its enantiomerically pure form, styrene (CH2CHPh)O and cyclopentene oxides [CH(CH2)3CH]O. In the case of propylene oxide, reactions have been found to be quantitatively and regiospecifically driven to the less congested epoxide carbon atom.
We succeeded in isolating unusual hapticity modes (eta1 or eta3) by reacting [Ind*]- or [Flu*]- with Re carbonyl halides1, whereas the eta5-coordination has been accomplished with FeCl2, yielding substituted metallocenes of the type [eta5-C9H6(CH2CHMe)OSiMe3]2Fe as further examples of planar chirality (2). Reaction between Na[C5H4(CH2CHPhOH)] and [Rh(COD)Cl]2, afforded the desired piano stool complex [eta5-C5H4(CH2CHPhOH)]Rh(COD).
1-S. Cerini, PhD Thesis, University of Bologna, 2004.
2- Paley R.S.; Chem.Rew.; 2002; 102; 1493, and references therein
Ligand Control in Multihaptotropic O-Indenyl Rhenium Systems. Experimental and Theoretical Study
No full textThe synthesis of a novel class of alcohol- and ether-functionalized indenyl ligands, focusing on the haptotropic rearrangements of the hybrid O-indenyl rhenium species, is herein described. η1-
Indx OMeRe(CO)5 (12x) and η3-IndxOMeRe(CO)4 (13x, x=a, d) [IndaOMe=C9H6CH2CH(Me)OMe, 1a; Indd OMe=C9H6CH(CH2)3CHOMe, 1da] are examples of σ and allylic intermediates in the Cp
substitution. The tuning of stereoelectronic effects of the functionalized alkyl chain or the coordinating solvent (MeCN, THF) allows the study of the relative stabilities of the intercepted solvento species η5-Indb OMeRe(CO)2(NCMe), 14b, η5-Indc OMeRe(CO)2(THF), 15c, or the chelate [η5:k1-OIndb, c ORe(CO)2], 16b,c {Indb OMe=[C9H6CH2CH(Ph)OMe]-, 4b; Indc OMe=[C9H6CH(Ph)CH2OMe]-, 4c}. DFT calculations reported on some of the IndO systems have been compared with those of smaller (CpO) 5a or larger (Flua O) 10a congeners, confirming the experimental findings. As peculiar examples of the underrepresented low-valent rhenium alkoxy species, the isolation of k1-O-HIndxORe(CO)5 [x=a, b] is also reporte
Chimica metallorganici a basso impatto ambientale: Sintesi e Coordinazione di leganti Ciclopentadienilici plurifunzionalizzati
No full text[RIASSUNTO (ABSTRACT)
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
Eco-Friendly New Ligands for Catalistys Design: Chemistry of Multidentate O-Functionalized Cp Ligands and Rh-Coordination”
No full text[RIASSUNTO (ABSTRACT)
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