1,721,053 research outputs found
Reactions of organic azides with noble metal carbonyl halides
No full textThe preparation of some new organometallic derivatives of rhodium(III), obtained by the reaction of [Rh(CO)2Cl]2 with benzoyl azide in C5H6 or THF, are described.
The chemical behaviour and IR and NMR data for the adducts with triphenylphosphine, p-toluidine, pyridine and 3,4-lutidine of formula [Rh(C6H4CONH)L(CO)Cl] show that they can be considered as benzoylimido derivatives of rhodium(III)
Reactions of acetylenes with noble-metal carbonyl halides II. Insertions into the chloro-platinum bond
No full textThe reaction of dichlorodicarbonylplatinum with ROOCCCCOOR (R = CH3, C2H5) in benzene and toluene gives carbonylchloro(1,2-trans-dicarboalkoxy-2-chloroethenyl)platinum compounds by insertion of the active acetylene molecule into the PtCl bond. These chelated stable square-planar vinyl derivatives react with neutral donor ligands to give simple σ-alkenyl derivatives: [Pt(CO)Cl(ROOCCC(Cl)COOR)L] (L = C5H5N, CH3C5H4N), [PtCl(ROOCCC(Cl)COOR)L2] (L = PPh3, PCH3Ph2), and [PtCl(ROOCCC(Cl)COOR)(LL)] (LL = DPE, bipy, Me2bipy). The anionic species [cis-Pt(CO)X2(ROOCCC(Cl)COOR)]- have been isolated as PPN salts by treating the vinyl complexes with Cl-, I- or SCN-. The stereochemistry has been elucidated from spectroscopic data (IR and 1H NMR)
Reactions of acetylenes with noble-metal carbonyl halides .3. chemical and structural studies of sigma-alkenyl complexes of platinum(II)
No full textThe reaction of [Pt(CO)Cl(ROOCCC(Cl)COOR)] and of the anions [cisPt(CO)Cl2(ROOCCC(Cl)COOR)]- (R = Me or Et) with primary and secondary alcohols (MeOH, EtOH, n-PrOH, i-PrOH, allyl-OH) gives rise to specific alcoholysis of the γ-alkoxy group. The specificity is interpreted in terms of the interaction of the β-carboalkoxy group with platinum. The crystal structure of (PPN)[cis-Pt(CO)Cl2(EtOOCCC(Cl)COOPr-i)] has been solved by X-ray analysis
Reactions of acetylenes with noble-metal carbonyl halides. Part 4. The formation of a platinaoxacyclopentenone ring
No full textThe compound [N(PPh3)2][cis-Pt{C(CO2R)=C(Cl)CO 2R}(CO)Cl2] (1; R = Me or Et) reacts with water in polar solvents to give [N(PPh3)2][Pt{C(CO2R)=C(Cl)COO}(CO)Cl]}(2), containing a platinaoxacyclopentenone ring. In anhydrous conditions [Pt(CO)2Cl2] reacts with RO2CC≡CCO2R to give the insoluble polymeric species [{Pt[C(CO2R]=C(Cl)COO](CO)}n] (7) which has been characterized both by conversion into (2) and by reaction with uni- and bi-dentate ligands to give [Pt{C(CO2R)=C(Cl)COO}L2] (L = PPh3, PMePh2, or PEtPh2), [Pt{C(CO2R)=C(Cl)COO}(L-L)] [L-L = 2,2′-bipyridine(bipy),4,4′-dimethyl-2,2′-bipyridine (dmbipy), or 1,2-bis(diphenylphosphino)ethane (dppe)], and [Pt{C(CO2R)=C(Cl)COO}(CO)L] [L = pyridine (py), methylpyridine (mpy), or dimethylpyridine (dmpy)], where the metallo-organic ring is preserved. No breaking of the ring was observed on reaction with chlorine and hydrochloric acid; conversely alkyl iodide gave [Pt{C(CO2R)=C(Cl)CO2R′}(CO)I] which is readily converted into salt-like compounds of type (1) by reaction with [N(PPh3)2]Cl. A cyclisation mechanism is proposed for both the reaction in anhydrous conditions and that in the presence of water. Crystals of [N(PPh3)2][Pt{C(CO)2Me]}=C(Cl)COO}(CO)Cl(2b) are triclinic, space group P1, with a = 17.144(5), b = 11.975(4), c = 10.386(4) Å, α = 106.62(8), β = 77.07(7), γ = 95.94(7)°, and Z = 2. The crystal structure has been solved by the heavy-atom method from counter data and refined by least squares to a final R of 0.041 (for 3 055 observed reflections). The structure consists of discrete anionic molecules and cationic counter ions, [N(PPh3)2]+
Reactions of acetylenes with noble-metal carbonyl halides . V. Cationic tetraalkylcyclobutadiene platinum(II)compounds
No full text
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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