1,721,010 research outputs found
Synthesis of [Bis(2-PyridylMethyl)amine]methylpalladium(II) Complexes as Catalysts for the CO-C2H4 Copolimerization
No full textCrystal Structures and Properties of (Au(phen)((CN)0.92Br0.08)2)Br and [Au(phen)(CN)((CN)0.82Br0.18)].0.5trans-[Au(CN)2Br2].0.5Br.phen (phen = 1,10-phenantroline) obtained by disproportion of Five-co-ordinated Bromodicyano(1,10-phenantroline)gold(III). Two exemples of secondary Co-ordination and CN/Br disorder in square-planar gold(III) complexes.
No full textfull title:Crystal structures and properties of [Au(phen){(CN)0.92Br0.08}2]Br and [Au(phen)(CN){(CN)0.82Br 0.18}]·0.5trans-[Au(CN)2Br 2]·0.5Br·phen (phen = 1,10-phenanthroline) obtained by disproportionation of five-co-ordinate bromodicyano(1,10-phenanthroline)gold(III). Two examples of secondary co-ordination and CN/Br disorder in square-planar gold(III) complexes The disproportionation of neutral five-co-ordinate [Au(phen)(CN)2Br] (phen = 1,10-phenanthroline) in dimethylformamide (dmf) gives a conducting solution from which two charged species, [Au(phen){(CN)0.92Br0.08}2]Br (1) and [Au(phen)(CN){(CN)0.82Br 0.18}]·0.5trans-[Au(CN)2Br 2]·0.5Br·phen (2), have been separated and characterized by single-crystal X-ray analysis. Crystals of (1) are orthorhombic, space group Fmm2, Z = 4 with a = 6.515(1), b = 11.76(2), c = 18.666(2) Å. Crystals of (2) are triclinic, space group P1, Z = 2 with a = 9.149(3), b = 9.263(3), c = 15.485(5), α = 93.58(2), β = 105.10(2), γ = 95.49(2)°. The structure..
Crystal structure of square-planar [1,2-bis(phenylsulfanyl)ethane]dihalogenoplatinum(II) complexes: cis-chelate effect and mutual trans influence
No full textThe crystal structures of six isomorphous [1,2-bis(phenylsulfanyl)ethane]dihalogenoplatinum(II) square-planar neutral complexes, i.e. dichloro (1), dibromo (2), diiodo (3), chlorobromo (4), chloroiodo (5) and bromoiodo (6) species, have been determined by the single-crystal X-ray diffraction technique. Crystals are monoclinic, space group P2(1)/c, Z=4, and their structures have been solved from three-dimensional counter data by Patterson and Fourier methods. Mixed dihalogeno species are disordered as far as the positions of the two halides are concerned and refinements have been carried out with occupancies of 0.5. The platinum atom is coordinated by means of the two sulfur atoms of the bidentate ligand and two halogen atoms in cis position. Comparison with other classes of platinum(II) complexes, carrying either chelating or monodentate thioetheric ligands and halides, allows to estimate a cis-chelate effect as well as the mutual trans influence of the different ligands
Crystal structure of cationic square planar platinum(II) complexes containing the tridentate chelate ligand 2,6-bis(methylthiomethyl)pyridine
No full textThe crystal structures of four platinum(II) complex cations containing the organic ligand 2,6-bis(methylthiomethyl)pyridine (SNS), [Pt(SNS)Cl]+ (1), [Pt(SNS) (SCN)]+ (2), [Pt(SNS)Br]+ (3) and [Pt(SNS)(Py)]2+ (4) have been determined by X-ray diffraction. In all complexes SNS behaves as a tridentate neutral ligand with the two sulphur atoms in trans positions to each other. The fourth coordination position, trans to the nitrogen atom of SNS, is occupied either by a monodentate chloride, sulphur-bonded thiocyanate, bromide or nitrogen of a pyridine molecule, respectively, in a square planar arrangement. No Pt-Pt interactions in the linear chain are present. Pt-N(pyridine) bond distances are related to the charge of the complexes
Crystal structure of bis-cationic square planar platinum(II) complexes containing the tridentate chelate ligand 2,6-bis(methylthiomethyl)pyridine and para-substituted pyridines
No full textThe crystal structure of five tetracoordinate bis-cationic platinum(II), complexes containing the chelating ligand 2,6-bis (methylthiomethyl) pyridine (SNS) and para-substituted pyridines [Pt(SNS)p-X-py](2+) (p-X = CN, COOH, NH2, Cl, CH3) have been determined by X-ray diffraction. In all complexes SNS behaves as a tridentate neutral ligand, with the two sulfur atoms in trans positions to each other and an approximate C-2 symmetry with the two methyl groups on the opposite sides of the coordination plane. The fourth position, trans to the nitrogen atom-of SNS, is occupied by a para-substituted pyridine systematically rotated with respect to the platinum coordination plane. No Pt-Pt and ligand pi-pi interactions are present
Base hydrolysis kinetics and equilibria of [bis(2-pyridylmethyl)amine]chloroplatinum(II) and crystal and molecular structures of [Pt(bpma)Cl]Cl·H2o and [Pt(bpma)(OH2)](ClO4) 2·2H2O
No full textThe kinetics of base hydrolysis of [Pt(bpma)Cl]Cl [bpma = bis(2-pyridylmethyl)amine] have been studied (5 × 10-4 ≤ [OH-] ≤ 0.2 mol dm-3) at 25°C and I = 0.2 mol dm-3 by UV-Vis spectrophotometry. The derived rate law is consistent with a mechanism involving a rapid preequilibrium between the substrate [Pt(bpma)Cl]+ and the amido species [Pt(bpmaH-1)Cl] (pKa1 = 12.3) followed by slow solvolysis to give the corresponding aqua species [Pt(bpma)(OH2)]2+ [ks = (2.8 ± 0.2) × 10-4 s-1] and [Pt(bpmaH-1)(OH2)]+ [ks′ = (3.28 × 0.02) × 10-3 s-1] which undergo deprotonation and are converted to unreactive hydroxo species. The aqua complex [Pt(bpma)(OH2)](ClO4) 2·2H2O, independently isolated in the solid, behaves as a dibasic acid in water solution(25°C, I = 0.2 mol dm-3), the two ionization constants being related to the dissociation of the water molecule in the aquoamine (pK1 = 5.4 ± 0.1) and of the amino group in the hydroxo-amino species (pK2 = 11.5 ± 0.1), respectively. The X-ray crystal structures of [Pt(bpma)Cl]Cl·H2O and [Pt(bpma)(OH2)](ClO4) 2·2H2O are reported. © 2002 Elsevier Science Ltd. All rights reserved
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
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