1,721,034 research outputs found
On the self assembly of a trans-dibromo-bis-(dppfo<sub>2</sub>) iron (III), a ferrocene-ligand complex, dppfo<sub>2</sub> = [(ƞ<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>P(O)Ph<sub>2</sub>)<sub>2</sub>Fe]: Letting nature do the work
No full textThe octahedral iron complex trans-[{O,O-(ƞ5-C5H4P(O)Ph2)2Fe}2Fe(III)Br2][Fe(III)Br4]has been prepared by self-assembly simply by adding anhydrous ferric chloride to a dichloromethane/methanol solution of dppf and 1,1,2,2-tetrabromoethane and then leaving to form a complex slowly. The key factor in the self-assembly is the addition of 1,1,2,2-tetrabromoethane which is the source of the bromide and is responsible for acid catalysed hydrolysis of ferric chloride.</p
1,1′,2,2′-tetralithioferrocene and 1,1′,2,2′,3,3′-hexalithioferrocene: useful additions to ferrocene precursor compounds
No full textThe direct synthesis of 1,1′,2,2′-tetralithioferrocene from1,1,2,2tetrabromoferrocene is reported. In addition, the related 1,1′,2,2′,3,3′-hexalithioferrocene is also described, prepared directly from 1,1′,2,2′,3,3′-hexabromoferrocene. These lithioferrocenes may be isolated as orange red (tetralithio) and red (hexalithio) powders, respectively. When these are prepared in situ and reacted with chlorotrimethylsilane, the corresponding 1,1′,2,2-tetrakis(trimethylsilyl)ferrocene and 1,1′,2,2′,3,3′′-hexakis(trimethylsilyl)ferrocene are obtained as red and crimson crystalline solids, respectively. The single-crystal structures of 1,1′,2,2′-tetrakis(trimethylsilyl)ferrocene (11) and 1,1′,2,2,3,3′-hexakis(trimethylsilyl)ferrocene (12) have been determined and are described
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
A Rapid General Synthesis and the Spectroscopic Data of 2,2′-Bis-(di-isopropylphosphino)-1,1′-dibromoferrocene, (bpdbf), 1,1′,2,2′-Tetrakis-(di-isopropylphosphino) Ferrocene, (tdipf) and Related Ligands: Taking dppf into the Future
No full textIn this paper, the clean high yielding, synthesis, and structure of the tetraphosphine ligand, 1,1′,2,2′-tetrakis-(di-isopropyl-phosphino)ferrocene, (tdipf), is described. In addition, improved synthesis methods for 1,1′,2,2′-tetrakis(diphenylphosphino)ferrocene, (tppf), and 2,2′-bis-(diphenylphosphino)-1,1′-dibromoferrocene are also reported, and the synthetic method is generalised to include the synthesis of 3,3′-bis-(diphenylphosphino)-1,1′,2,2′-tetrabromoferrocene. The related ligands 2,2′-bis-(iso-propylphosphino)-1,1′-bis-diphenylphosphinoferrocene (diprdppf) and 2,2′-bis-(di-isopropylphosphino)-dibromoferrocene have also been prepared and characterised. The crystal structure of the square planar bimetallic nickel (II) dichloride of tdipf is also described, together with a brief NMR study investigating the synthesis of this and related metal complexes. The crystal structures of the palladium and platinum dichloride complexes of 2,2′-bis-(di-isopropylphosphino)-1,1′-dibromoferrocene, bpdbf, are also discussed in the context of comparison with previously known crystal structures in the same general family. A general discussion on the synthetic methodology is given, along with indications for future research that other researchers might explore
Ferrocenylmethylphosphines ligands in the palladium-catalysed synthesis of methyl propionate
No full textThe synthesis of a range of novel ferrocenylmethylphosphanes ligands is described which have direct application in the palladium catalysed reaction of carbon monoxide, methanol and ethene to obtain methyl propionate, a key intermediate in the preparation of methylmethacrylate
Directly-linked intramolecular donor-acceptor compounds of ferrocene and tetracyanoanthraquinodimethane
No full textTwo new intramolecular donor-acceptor species have been prepared linking ferrocene (Fc) directly to either the 1 (1) or 2 (2) positions of tetracyanoanthraquinodimethane (TCNAQ). Spectroscopic and electrochemical characterisation show significant differences between 1 and 2, revealing the importance of the position of attachment. The Fc part is a poorer donor and the TCNAQ part a poorer acceptor than the respective parent molecules and an intramolecular charge-transfer transition is observed at 604 nm (1) and 634 nm (2). The X-ray structure of 1 shows the TCNAQ component with the typical folded conformation with the ferrocene unit rotated by 38.0 degrees relative to the ring to which it is attached
The first 1,2,3-tris(phosphinomethyl)ferrocene
No full textThe synthesis of the first 1,2,3-tris(phosphinomethyl)ferrocene is reported using an efficient lithiation and quench technique in which dimethylaminomethylferrocenes are useful intermediates
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