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Hard/soft interactions : Group IV metal halide complexes with soft donor ligands of groups 15 and 16
No full textThe complexes fac-(Mn(CO)3(η3-L)]CF3SO3 (L = [12]-, [14], [16]-aneS4 and [15]aneS5) have been prepared and characterised by mass spectroscopy, IR and multinuclear (1H, 13C{1H}, 55Mn) NMR spectroscopy and elemental analysis. Single crystal X-ray diffraction of adducts with L = [12]aneS4 and [15]aneS5 confirmed fac coordination of the ligand. Decarbonylation with Me3NO afforded cis-[Mn(CO)2(η4-L)]CF3SO3 as the first examples of thioether stabilised [Mn(CO)2]+. These were characterised as above and X-ray crystallography of adducts with L = [12]-, [16]-aneS4 and [15]aneS5 revealed the consequences of increasing macrocyclic coordination.The coordination chemistry of soft donor ligands with Group IV metal halides has been investigated. The complexes [TiX4(L2)] (L2 = MeE(CH2)nEMe, o-C6H4(EMe)2, X = Cl, Br; L2 = PhE(CH2)nEPh, X = Cl; E = S, Se, n = 2,3) and [TiI4(L2)] (L2 = MeSe-(CH2)nSeMe, o-C6H4(SeMe)2) have been prepared and characterised by electronic, IR and multinuclear (1H, 13C{1H}, 77Se{1H}) NMR spectroscopy and elemental analysis. NMR spectroscopy revealed dynamic inversion and dissociation processes in solution. X-ray crystallography of [TiCl4(L2)] (L2 = o-C6H4(SeMe)2 and MeE(CH2)nEMe, E = S, n = 2,3; E = Se, n = 3) confirmed cis coordination of the ligands and revealed trends in the coordination geometry at Ti(IV).Analogous reactions with Group 15 ligands afforded [TiX4(L2)] (L2 = Ph2As-(CH2)2AsPh2, Ph2P(CH2)nPPh2 (n = 1,2,3), o-C6H4(PPh2)2, o-C6H4(EMe2)2, E = As, P) and [TiI4{o-C6H4(EMe2)2}] (E = As, P). Reactions with 2 equivalents of ligand afforded rare 8-coordinate [TiX4(L2)2] for L2 = o-C6H4(EMe2)2, E = As, P, X = Cl, Br, I. The complexes were characterised by electronic, IR and multinuclear (1H, 13C{1H}, 31P{1H}) NMR spectroscopy and elemental analysis. X-ray crystallography of [TiCl4(o-C6H4(PMe2)2)] and [TiX4(o-C6H4(EMe2)2)2] (E = P, X = Cl, Br; E = As, X = Br) revealed changes in the geometry at Ti(IV) on increasing coordination number.</p
Titanium, zirconium and hafnium halide complexes of trithioether and triselenoether ligands
No full textThe reaction of TiX4(X = Cl or Br) with the tripodal ligands MeC(CH2SMe)(3) or MeC(CH2SeMe)(3), (L-3) in anhydrous n-hexane or CH2Cl2 produced the extremely moisture sensitive complexes [TiX4(L-3)]. These were characterised by microanalysis, IR, UV-Vis and variable temperature H-1, C-13{H-1} and Se-77 NMR spectroscopy. The NMR studies showed that in solution in CH2Cl2 the complexes contain L-3 bound as bidentates, and that pyramidal inversion and exchange between the free and coordinated chalcogen donors is rapid at room temperature. Ligand dissociation/exchange increases TiCl4<TiBr4 and MeC(CH2SMe)(3) < MeC(CH2SeMe)(3.) and attempts to isolate TiI4 analogues were unsuccessful. The reactions of [MCl4(Me2S)(2)] (M = Zr or Hf) with (L-3) in anhydrous CH2Cl2 produces white or cream 7-coordinate [MCl4(L-3)], which are insoluble in chlorocarbon solvents. The reactions of TiX4 (X = Cl, Br or I) with the trithia-macrocycles [9]aneS(3) and [10]aneS(3) produced [TiX3([n]aneS(3))]X, whilst reaction of TiCl4. SbCl5 and [9]aneS(3) in anhydrous CH2Cl2 gave [TiCl3([9]aneS(3))]SbCl6. Spectroscopic studies suggest these macrocyclic compounds contain 6-coordinate cations. [TiX3([n]aneS(3))] (n = 9 or 10) but with Zr and Hf the complexes [MCl4([n]aneS(3))] are 7-coordinate and neutral
Synthesis, properties and crystal structures of 6-, 7- and 8-coordinate Zr(IV) and Hf(IV) complexes involving thioether and selenoether ligands
No full textA series of 6-,7- and 8-coordinate complexes of the form [MCl4(L-L)] (M = Zr, Hf; L-L = MeE(CH2)(2)EMe), [ZrCl4([9]aneS(3))] and [MCl4{MeE(CH2)(2)EMe}(2)] (E = S or Se) has been obtained in moderate to high yield by reaction of [MCl4(Me2S)(2)] with one (or three for the 1 : 2 M : L-L species) molar equivalents of L-L in rigorously anhydrous CH2Cl2. The poorly soluble products have been characterised by far IR spectroscopy, diffuse reflectance UV-Vis spectroscopy and microanalyses. H-1 NMR data are reported for certain systems, although in the majority of cases the very poor solubility prevented useful NMR experiments. The crystal structures of six representative examples, the distorted octahedral [ZrCl4(Me2S)(2)] and [HfCl4{MeSe(CH2)(2)SeMe}], the metallocyclic [(ZrCl4)(2){mu-MeS(CH2)(3)-SMe}(2)], the flattened dodecahedral [ZrCl4{MeS(CH2)(2)SMe}(2)] and [HfCl4{MeS(CH2)(2)SMe}(2)] and the 7-coordinate [ZrCl4([9]aneS(3))] are also described. The crystal structure of [Me2SCH2Cl](2)[Zr2Cl10], formed during reaction of [ZrCl4(Me2S)(2)] with MeSe(CH2)(2)SeMe in CH2Cl2 is also presented
Coordination networks derived from antimony(III) halide complexes with thio- and seleno-ether ligation
No full textAntimony(III) halides form highly unusual infinite one- or two-dimensional networks when coordinated to dithio- or diseleno-ether ligands or macrocyclic selenoethers. The structures adopted are contrasted with those observed for related bismuth(III) species
Rational design of open-framework coordination solids - Synthesis and structure of Co-5(OH)(2){1,2,4,5-(O2C)(4)C6H2}(2)(H2O)(4) • xH(2)O
No full textA strategy for preparing open-framework coordination solids by hydrothermal synthesis has been developed and tested by the synthesis of a new porous cobalt carboxylate which can be dehydrated by heating to give a material with coordinatively unsaturated metal ions
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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