1,721,392 research outputs found
Reduction of a Cerium(III) Siloxide Complex To Afford a Quadruple-Decker Arene-Bridged Cerium(II) Sandwich
No full textbibtex: ISI:000416244200030 bibtex\location:'POSTFACH 101161, 69451 WEINHEIM, GERMANY',publisher:'WILEY-V C H VERLAG GMBH',type:'Article',affiliation:'Mazzanti, M (Reprint Author), Ecole Polytech Fed Lausanne, Inst Sci & Ingn Chim, CH-1015 Lausanne, Switzerland. Kelly, Rory P.; Scopelliti, Rosario; Mazzanti, Marinella, Ecole Polytech Fed Lausanne, Inst Sci & Ingn Chim, CH-1015 Lausanne, Switzerland. Maron, Laurent, Inst Natl Sci Appl, Lab Phys & Chim Nanoobjets, F-31077 Toulouse 4, France.','author-email':'[email protected]',da:'2018-12-05','doc-delivery-number':'FN8BR',eissn:'1521-3773','funding-acknowledgement':'Ecole Polytechnique Federale de Lausanne (EPFL); Swiss National Science Foundation [200021\₁57158]','funding-text':'We thank Dr. F. Fadaei Tirani for her contribution to the Xray single-crystal structure data collection and analyses. We thank Dr. Euro Solari for elemental analysis. L.M. is a member of the Institut Universitaire de France. CAlmip is acknowledged for a generous grant of computing time. This work was supported by the Ecole Polytechnique Federale de Lausanne (EPFL) and by the Swiss National Science Foundation grant (number 200021\₁57158).','journal-iso':'Angew. Chem.-Int. Edit.','keywords-plus':'OXIDATION-STATE; ELECTRONIC-STRUCTURE; DIVALENT LANTHANIDE; AB-INITIO; LIGAND REORGANIZATION; DIURANIUM COMPLEXES; BONDING ENERGETICS; BUILDING-BLOCK; MULTIPLE BOND; METAL CENTER','number-of-cited-references':'66','orcid-numbers':'Mazzanti, Marinella/0000-0002-3427-008X','research-areas':'Chemistry','times-cited':'4','unique-id':'ISI:000416244200030','usage-count-last-180-days':'4','usage-count-since-2013':'22','web-of-science-categories':'Chemistry, Multidisciplinary'\International audienceOrganometallic multi-decker sandwich complexes containing f-elements remain rare, despite their attractive magnetic and electronic properties. The reduction of the Ce-III siloxide complex, [KCeL4] (1; L = OSi(OtBu)(3)), with excess potassium in a THF/toluene mixture afforded a quadruple-decker arene-bridged complex, [K(2.2.2-crypt)](2)[\(KL3Ce)(mu-eta(6):eta(6)-C7H8)\(2)Ce] (3). The structure of 3 features a [Ce(C7H8)(2)] sandwich capped by [KL3Ce] moieties with a linear arrangement of the Ce ions. Structural parameters, UV/Vis/NIR data, and DFT studies indicate the presence of Ce-II ions involved in delta bonding between the Ce cations and toluene dianions. Complex 3 is a rare lanthanide multi-decker complex and the first containing non-classical divalent lanthanide ions. Moreover, oxidation of 1 by AgOTf (OTf = O3SCF3) yielded the Ce-IV complex, [CeL4] (2), showing that siloxide ligands can stabilize Ce in three oxidation states
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
Organometallic rhodium(iii) and iridium(iii) cyclopentadienyl complexes with curcumin and bisdemethoxycurcumin co-ligands
Get PDFA series of half-sandwich cyclopentadienyl rhodium(iii) and iridium(iii) complexes of the type [Cp*M(curc/bdcurc)Cl] and [Cp*M(curc/bdcurc)(PTA)][SO3CF3], in which Cp* = pentamethylcyclopentadienyl, curcH = curcumin and bdcurcH = bisdemethoxycurcumin as O^O-chelating ligands, and PTA = 1,3,5-triaza-7-phosphaadamantane, is described. The X-ray crystal structures of three of the complexes, i.e. [Cp*Rh(curc)(PTA)][SO3CF3] (5), [Cp*Rh(bdcurc)(PTA)][SO3CF3] (6) and [Cp*Ir(bdcurc)(PTA)][SO3CF3] (8), confirm the expected "piano-stool" geometry. With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma (A2780 and A2780cisR) cells and also to non-tumorigenic human embryonic kidney (HEK293) cells, but lack the cancer cell selectivity observed for related arene ruthenium(ii) complexes
Carboxylic Acid Functionalized Clathrochelate Complexes: Large, Robust, and Easy-to-Access Metalloligands
No full textPolycarboxylate ligands are among the most important building blocks for the synthesis of metal-organic frameworks (MOFs). The ability to access these ligands in an efficient way is of key importance for future applications of MOFs. Here, we demonstrate that mono- and dinuclear clathrochelate complexes are versatile scaffolds for the preparation of polytopic carboxylate ligands. The largely inert clathrochelate complexes have a trigonal-bipyramidal shape. The synthesis of functionalized clathrochelates with two, three, four, or five carboxylic acid groups in the ligand periphery can be achieved in a few steps from simple starting materials. Apart from being easily accessible, the metalloligands display interesting characteristics for applications in metallasupramolecular chemistry and materials science: they are rigid, large (up to 2.2 nm), and robust and they can show additional functions (e.g., fluorescence or extra charge) depending on the metal ion that is present in the clathrochelate core. The utility of these new metalloligands in MOF chemistry is demonstrated by the synthesis of zinc- and zirconium-based coordination polymers. The combination of Zn(NO3)(2) with clathrochelates having two or three carboxylic acid groups gives MOFs in which the clathrochelate ligands are connected by Zn4O clusters or zinc paddlewheel links. The structures of the resulting two- and three-dimensional networks could be established by single-crystal X-ray crystallography. The reaction of carboxylic acid functionalized clathrochelates with ZrCl4 gives amorphous powders that display permanent porosity after solvent removal.European Union [264645]; Swiss National Science Foundation; EPF
to Epoxides
No full textValorization of CO2, an abundant C(1) synthon, into platform chemicals is of growing interest. In this context, a key reaction is the cycloaddition of CO2 to epoxides to form carbonates (CCE). A series of organocatalysts for this reaction, based on imidazolium salts modified with a styrene functional group and a second variable functional group, were prepared and characterized. Both the ionic salts and ionic polymers derived from the salts were evaluated in this reaction. In general, the monomers perform slightly better than the polymers; however, the latter are considerably more convenient to use. Of the catalysts studied, the ionic polystyrene imidazolium salt with an ammonium functionality shows highest activity, tolerates a range of epoxides, and can be recycled multiple times without loss of activity
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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