1,721,006 research outputs found
Crystral Structures of a Bis(cyclopentadienyl)(Z)-enyne Framed Manganese(I)-Rhenium(I) Complex and its [Co2(CO)8] Adduct
No full textRemarkable, Sterically Induced Rate Enhancement in the Insertion of Allenes into Palladium-Methyl Bonds
No full textSynthesis and X-ray Structural Characterization of Two Unbridged Diplatinum(III) Compounds: cis- and trans-Bis[bis(1-imino-1-methoxyethane)trichloroplatinum(III)]. Transient Species in the Oxidation of Platinum(II) to Platinum(IV)
No full textFive-coordinate Platinum(II) Alkyne Complexes a Route to Alkenyl and Vinylidene Pt(II) species
No full text
STRUCTURAL CHARACTERIZATION OF A TRINUCLEAR COMPLEX OF PLATINUM(II) CONTAINING BRIDGING 1-METHYLCYTOSINE LIGANDS - A COMBINED X-RAY AND MULTINUCLEAR NMR-STUDY
No full textThe dinuclear complexes cis-[(PMe3)2Pt(1-MeCy(-H))]2X2 (X = NO3- (1A), ClO4- (1B)), containing NH2-deprotonated 1-methylcytosine (1-MeCy(-H)) ligands, in aqueous or DMSO solution, at 80-degrees-C convert quantitatively into the corresponding trinuclear derivatives cis-[(PMe3)2Pt(1-MeCy(-H))]3X3(2A,B) which have been characterized in the solid state by single-crystal X-ray analysis and in solution by multinuclear (H-1, P-31, Pt-195, C-13, and N-15) NMR spectroscopy. The nitrate salt (2A) crystallizes from ethanol in the triclinic system, space group Pl. The crystals, stable only in the presence of the solvent, have the following cell dimensions: a = 13.542(5) angstrom, b = 17.352(5) angstrom, c = 20.721(6) angstrom, alpha = 113.13(2)degrees, beta = 104.30(3)degrees, gamma = 95.77(3)degrees, Z = 2. The structure, formulated as cis-[(PMe3)2Pt(1-MeCy(-H))]3(NO3)3.EtOH.H2O, was refined to R = 6.3 and R(w) = 6.3. Better structural data were obtained with the perchlorate derivative (2B), cis-[(PMe3)2Pt(1-MeCy(-H))]3(ClO4)3.2H2O, whose structure was refined to R = 4.4 and R(w) =4.9. The colorless prisms formed from aqueous solutions have the following crystallographic data: triclinic system, space group P1BAR, a = 14.634(7) angstrom, b = 14.791(9) angstrom, c = 14.980(9) angstrom, alpha = 101.93(5)degrees, beta = 103.46(5)degrees, gamma = 90.50(4)degrees, Z = 2. In both salts, the molecular structure of the cationic complex contains three cis-(PMe3)2Pt units linked to three 1-methylcytosine anions through the N(3) and N(4) atoms. The resulting 12-membered ring contains the pyrimidinic rings almost perpendicular to the plane defined by the metal atoms. Each platinum has a square-planar coordination with a Pt...Pt distance of 5.2A. The H-1, P-31, and C-13 NMR spectra indicate that the approximate S3 symmetry of the cation is maintained in solution. The compounds 1A and 2A were also characterized by N-15 NMR spectroscopy, at natural abundance. The spectroscopic data, obtained in DMSO-d6 solution, are compared with those of the derivative cis-[(PMe3)2Pt(1-MeCY)2](NO3)2 containing as ligands the neutral N(3)-bonded nucleobase. The dinuclear and trinuclear complexes exhibit very similar N-15 chemical shifts and 2J(PN) coupling constants but remarkably different from those of the mononuclear complex
First direct synthesis of a corrole ring from a monopyrrolic precursor. Crystal and molecular structure of (triphenylphosphine)-(5,10,15-triphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato) cobalt(III)-dichloromethane
No full textThe first synthesis of the corrole ring by self-condensation of a monopyrrolic unit is reported. The reaction occurs only in the presence of cobalt ions; it leads to the formation of (triphenylphosphine)(5,10,15-triphenyl-2,3,7,8,12, 13,17,18-octamethylcorrolato)cobalt(III), [Co(OMTPC)PPh3] and represents the first example of interconversion between a porphyrinoid and a corrole structure. Crystals of [Co(OMTPC)PPh3].CH2Cl2 have been obtained by slow diffusion of methanol into a dichloromethane solution of the complex and have been characterized by single-crystal X-ray analysis. They crystallize in the triclinic system, space group P1BAR, with a = 10.628 (2) angstrom, b = 11.585(2) angstrom, c = 22.352(4) angstrom, alpha = 84.93(2)-degrees, beta = 78.56(2)-degrees, gamma = 72.93(2)-degrees, and Z = 2. The structure was solved by heavy-atom methods and refined by least-square techniques to R = 0.051 for 6377 unique data [F(o) > 4 sigma(F(o))]. The analysis reveals the substantial planarity of the macrocyclic ring. In the 23-atom core of the corrole moiety each atom shows an average displacement from the plane of best fit of 0.14 angstrom, with the largest deviations being +0.33 and -0.33 angstrom for C(2) and C(12), respectively. The synthesis of diphenyl derivatives of corrole: (triphenylphosphine) (5,10-diphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato)cobalt(III), [Co(5,10-OMDPC)PPh3], and (triphenylphosphine) (5,15-diphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato)cobalt(III), [Co(5,15-OMDPC)PPh3], is also reported. Plausible reaction pathways leading to the formation of the two isomers are discussed together with the spectral properties of the complexes
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
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