Chemical, electrochemical and structural studies of some cis-dioxomolybdenum(VI) complexes of two tridentate ONS chelating ligands

Several cis-dioxomolybdenum complexes of two tridentate ONS chelating ligands H2L1 and H2L2 ( obtained by condensation of S-benzyl and S-methyl dithiocarbazates with 2-hydroxyacetophenone) have been prepared and characterized. Complexes 1 and 2 are found to be of the form MoO2 (CH3OH)L-1.CH3OH and MoO2L, respectively, (where L2-=dianion of H2L1 and H2L2). The sixth coordination site of the complexes acts as a binding site for various neutral monodentate Lewis bases, B, forming complexes 3 - 10 of the type MoO2LB (where B=gamma-picoline, imidazole, thiophene, THF). The complexes were characterized by elemental analyses, various spectroscopic techniques, ( UV-Vis, IR and H-1 NMR), measurement of magnetic susceptibility at room temperature, molar conductivity in solution and by cyclic voltammetry. Two of the complexes MoO2(CH3OH)L-1.CH3OH (1) and MoO2L1(imz) (5) were structurally characterized by single crystal X-ray diffraction. Oxo abstruction reactions of 1 and 5 led to formation of oxomolybdenum(IV) complex of the MoOL type.

Synthesis, chemical, electrochemical characterization of oxomolybdenum(V) complexes of 2-(3,5-dimethyl pyrazol-1-yl) benzothiazole ligand: crystal structure of ligand and oxomolybdenum(VI) complex and density functional theory (DFT) calculation

This work reports the ligational behavior of the neutral bidentate chelating molecule 2-(3,5-dimethyl pyrazol-1-yl) benzothiazole towards the oxomolybdenum(V) center. Both mononuclear complexes of the type (MoOX3L)-O-V and binuclear complexes of the formula (Mo2O4X2L2)-O-V (where X = Cl, Br) are isolated in the solid state. The complexes are characterized by elemental analyses, various spectroscopic techniques (UV-Vis IR), magnetic susceptibility measurement at room temperature, and cyclic voltammetry for their redox behavior at a platinum electrode in CH3CN. The mononuclear complexes (MoOX3L)-O-V are found to be paramagnetic while the binuclear complexes Mo2O4X2L2 are diamagnetic. Crystal and molecular structure of the ligand and the dioxomolybdenum complex (MoO2Br2L)-O-VI (obtained from the complex MoOBr3L during crystallization) have been solved by single crystal X-ray diffraction technique. Relevant DFT calculations of the ligand and the complex (MoO2Br2L)-O-VI are also carried out.

Dimer formation by symbiotic donor–acceptor interaction between two molecules of a specially designed dioxomolybdenum(VI) complex containing both donor and acceptor centers – A structural, spectroscopic and DFT study

This work presents a model study for the formation of a dimeric dioxomolybdenum(VI) complex [MoO2L]2, generated by simultaneous satisfaction of acceptor and donor character existing in the corresponding monomeric Mo(VI) complex MoO2L. This mononuclear complex is specially designed to contain a coordinatively unsaturated Mo(VI) acceptor centre and a free donor group, (e.g. –NH2 group) strategically placed in the ligand skeleton [H2L = 2-hydroxyacetophenonehydrazone of 2-aminobenzoylhydrazine]. Apart from the dimer [MoO2L]2, complexes of the type MoO2L·B (where B = CH3OH, γ-picoline and imidazole) are also reported. All the complexes are characterized by elemental analysis, spectroscopic (UV–Vis, IR, 1H NMR) techniques and cyclic voltammetry. Single crystal X-ray structures of [MoO2L]2 (1), MoO2L·CH3OH (2), and MoO2L.(γ-pic) (3) have been determined and discussed. DFT calculation on these complexes corroborates experimental data and provides clue for the facile formation of this type of dimer not reported previously. The process of dimer formation may also be viewed as an interaction between two molecules of a specially designed complex acting as a monodentate ligand. This work is expected to open up a new field of design and synthesis of dimeric complexes through the process of symbiotic donor–acceptor (acid–base) interaction between two molecules of a specially designed monomer.

Tempo, magnitude e o mito do cinema moderno

Neste texto, irei abordar três filmes ambientados em Portugal, cujas locações oferecem uma visão privilegiada da função do tempo e da magnitude no cinema, os quais, por sua vez, nos permitem reavaliar as categorias de clássico, moderno e pós-moderno aplicadas a esse meio. Trata-se de O estado das coisas (Der Stand der Dinge, Wim Wenders, 1982), Terra estrangeira (Walter Salles and Daniela Thomas, 1995) e Mistérios de Lisboa (Raúl Ruiz, 2010). Neles, a cidade se compõe de círculos viciosos, espelhos, réplicas e mise-en-abyme que interrompem o movimento vertiginoso característico da cidade modernista do cinema dos anos 20. Curiosamente, é também o lugar em que a assim chamada estética pós-moderna finalmente encontra abrigo em contos auto-irônicos que expõem as insuficiências dos mecanismos narrativos no cinema. Para compensá-las, recorre-se a procedimentos de intermídia, tais como fotografias de polaroid em O estado das coisas ou um teatro de papelão em Mistérios de Lisboa, que transformam uma realidade incomensurável em miniaturas fáceis de enquadrar e manipular. O real assim diminuído, no entanto, se revela um simulacro decepcionante, um ersatz da memória que evidencia o caráter ilusório da teleologia cosmopolita. Em minha abordagem, começarei por examinar a gênese interligada e transnacional desses filmes que resultou em três visões correlatas mas muito diversas do fim da história e da narrativa, típico da estética pós-moderna. A seguir, irei considerar o miniaturismo intermedial como uma tentativa de congelar o tempo no interior do movimento, uma equação que inevitavelmente nos remete ao binário deleuziano tempo-movimento, que também irei revisitar com o fim de distingui-lo da oposição entre cinema clássico e moderno. Por fim, irei propor a stasis reflexiva e a inversão de escala como demonominadores comuns entre todos os projetos ditos modernos, que por esta razão, segundo creio, são mais confiáveis que a modernidade enquanto indicadores de valores artísticos e políticos.