Dinuclear Copper(I) Complexes as Precatalysts in Ullmann and Goldberg Coupling Reactions

7 páginas, 3 figuras, 4 tablas, esquemas.The use of structurally well-characterized copper(I) species as precatalysts in C−N and C−S bond forming reactions is described. Two new dinuclear Cu(I) complexes containing two isomeric ligands of bis(7-azaindolyl)methane have been synthesized and fully characterized by NMR and X-ray diffraction studies. Both copper(I) species exhibit a 1:1 Cu/L ratio and have been used as precatalysts in the N-arylation of 2-pyrrolidinone and S-arylation of thiols with aryl iodides. The complexes efficiently catalyze these cross-coupling reactions, affording high yields of products under mild conditions.We thank MEC (Proyecto CTQ200800042BQU) and Junta de Andalucía (Proyecto P07FQM02745) for financial support. E.H. thanks MEC for a research fellowshipPeer reviewe

Del patrimonio a la cultura: evoluciones en la gobernanza urbana de Quito

Quito se convierte en 1978 en la primera ciudad, con Cracovia, en recibir por parte de la Unesco la distinción de Patrimonio Cultural de la Humanidad. El título, otorgado a la ciudad por la riqueza de su centro histórico, permite crear un nuevo espacio de gobernanza urbana, que se analiza como un campo patrimonial relativamente autónomo. El estudio de los actores involucrados en este campo, que intervienen en diferentes escalas —y de las definiciones oficiales de patrimonio producidas en este campo—, desde los años ochenta, ayuda a identificar con mayor claridad las evoluciones actuales y ver en qué medida son innovadores. Por lo tanto, el análisis de dos programas implementados en los últimos años por el gobierno municipal —la campaña Cuéntame tu Quito (un proceso participativo sobre el concepto de patrimonio) y la construcción del Parque Urbano Qmandá (una infraestructura deportiva y cultural)— permite observar la emergencia de políticas ya no solo patrimoniales sino culturales. Integradas en un marco ideológico nacional definido desde 2008 por la Constitución de Montecristi, el del Estado del Buen Vivir, reflejan el surgimiento de una nueva relación entre los quiteños y su patrimonio y, más allá, entre los  ciudadanos y su ciudad

Synthesis, structural characterization, reactivity, and catalytic properties of copper(I) complexes with a series of tetradentate tripodal tris(pyrazolylmethyl)amine ligands

Novel tris(pyrazolylmethyl)amine ligands TpaMe3, Tpa*,Br, and TpaBr3 have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper(I) salts as starting materials. Cationic copper(I) complexes [TpaxCu]PF6 (1-4) have been isolated from the reaction of [Cu(NCMe)4]PF6 and 1 equiv of the ligand. Complexes 2 (Tpax = Tpa*) and 3 (Tpax = TpaMe3) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpax ligand adopts a μ2: κ2:κ1-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper(I) source, neutral compounds 5-8 have been obtained. Complexes 6-8 exhibit a 1:1 metal-to-ligand ratio, whereas 5 presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa 2Cu4I4] units, in which Cu4I 4 presents a step-stair structure. The Tpa ligands bridge the Cu 4I4 clusters, adopting also a μ2: κ2:κ1-coordination mode. As observed for the cationic derivatives, the NMR spectra of 5-8 show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper(I) derivatives 1-4 with PPh3 and CO have been explored. In all cases, 1:1 adducts [TpaxCuL]PF6 [L = PPh3 (9-11), CO (12-15)] have been isolated. The crystal structure of [Tpa*Cu(PPh3)]PF6 (9) has been obtained, showing that the coordination geometry around copper(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts 13-15 exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR νCO stretching bands. Finally, the catalytic activities of complexes 1-4 have been demonstrated in carbene- and nitrene-transfer reactions. © 2014 American Chemical Society.Peer Reviewe