1,720,965 research outputs found
Federico da Montefeltro e Gubbio. «lì è tucto el core nostro et tucta l’anima nostra», a cura di Francesco P. Di Teodoro, con Lucia Bertolini, Patrizia Castelli, Fulvio Cervini, Cinisello Balsamo (MI), Silvana Editoriale, 2022 ISBN 9788836652587
No full textcatalogo della mostra di Gubbio giugno-ottobre 202
Copper(I)-imine complexes: Synthesis and catalytic activity in olefin cyclopropanation
No full textDifferent imine-type ligands, prepared by the condensation of anilines or of a-methylbenzylamine with 2-pyridinecarboxaldehyde (pyim1,2) or 2-quinolinecarboxaldehyde (quim1,2) were prepared. These species act as N,N'-bidentate, chelating ligands upon coordination to Cu(I): treatment of [Cu(PPh3)3Cl] with an equimolar amount of the ligands resulted in the displacement of two molecules of PPh3, giving rise to the formation of [Cu(pyim1,2)(PPh3)Cl] (1–2) and [Cu(quim1,2)(PPh3)Cl] (3–4), respectively. The copper derivatives 1–4 proved to be highly active catalysts in olefin cyclopropanation in the presence of ethyl diazoacetate, even using deactivated olefins (namely, 2-cyclohexen-1-one) as substrate. The X-ray structure of complex 2, [Cu(pyim2)(PPh3)Cl], is also reported
Synthesis and characterization of two polymorphic crystalline phases and an amorphous powder of nickel(II) bisimidazolate
No full textErato. Tersicore. Polimnia
No full textL'autrice presenta un’ innovativa interpretazione di Erato, Tersicore e Polimnia, parte del ciclo originariamente destinato al Tempietto delle Muse del Palazzo Ducale di Urbino (iniziato da Giovanni Santi e completato, dopo la sua morte, da Timoteo Viti), in cui le Muse sono raffigurate come fanciulle a grandezza naturale, che suonano o tengono in mano altrettanti strumenti musicali. L’analisi approfondita delle immagini permette di mettere in luce i peculiari significati ad esse assegnati, nell’ambito di un sofisticato programma iconografico-musicale di chiara ispirazione ficiniana.
L'autrice identifica, inoltre, le principali componenti tematiche ed iconografiche del programma, evidenziando come, grazie alla reinterpretazione in chiave attualizzante degli strumenti musicali dipinti (che trovano riscontro con i celebri strumenti ducali e in particolare con alcuni esemplari immortalati nelle tarsie nello Studiolo di Gubbio), le Muse del Tempietto vengano trasformate in divinità ‘federiciane’
New copper(I) and silver(I) triazolato-complexes: Synthesis, reactivity and catalytic activity in olefin cyclopropanation
No full textA new class of azolate ligands, deriving from the equimolar condensation of 3,5-diamino-1,2,4-triazole with salicylaldehyde (H3L1) and o-anisaldehyde (H3L2) was prepared. In their anionic form, these species act as bridging moieties upon coordination to Cu(I) and Ag(I), giving rise to the formation of dinuclear complexes with the ligand in the typical N,N'-exobidentate conformation. The copper derivative [Cu(H2L1)(CH3CN)]2 (1) showed attractive reactivity in the replacement of the labile acetonitrile molecules. In particular, it was possible to isolate a dinuclear copper(I)-carbonyl complex [Cu(H2L1)CO)]2 (4), by substitution of the nitrile with carbon monoxide. Moreover, the reaction of 1 with ethyl diazoacetate (EDA) in CH2Cl2 afforded a mono-carbene product, as established by 13C NMR data. Finally, the copper derivative 1 proved to be a highly diastereoselective catalyst in olefin cyclopropanation in the presence of ethyl diazoacetate. In the case of internal alkenes a trans:cis ratio of up to 97:3 was reached. The X-ray structure of a dinuclear Ag(I) complex, namely [Ag(H2L1)(PPh3)]2 (3), obtained by reacting the polymeric [Ag(H2L1)]n (2), with triphenylphosphine, is also reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Synthesis and characterization of 2-aminobenzoimidazolate group 11 coordination polymers: a combined X-ray powder diffraction and 13CP MAS NMR study
No full text1D coordination polymers of group 11 metal ions, having 2-aminobenzoimidazolate as building block, have been synthesized and fully characterized by X-ray powder diffraction and solid state CP/MAS (13)C NMR
Facile anaerobic oxidative dehydrogenation promoted by bases: The case of copper-2,4-dihydro-1H-benzo[d][1,3]oxazine complexes
No full textTwo new 2,4-dihydro-1H-benzo[d][1,3]oxazines (L1 and L2) were prepared by condensation of 2-quinolinecarboxaldehyde and 2-amino-benzyl alcohols and tested as N,N’-bidentate ligands toward CuCl2. Treatment of the resulting copper(II) derivatives with Et3N promoted an oxidative dehydrogenation yielding the corresponding copper(I) [Cu(L-ox)Cl] complexes, 2, (L-ox = 4H-benzo[d][1,3]oxazine). The [Cu(L2-ox)Cl] species, 2b, was characterized by single crystal X-ray diffraction, showing a trigonal geometry at the metal center and reacted with PPh3 and CO, affording [Cu(L2-ox)(PPh3)Cl], 4b, and [Cu(L2-ox)(CO)Cl], 6b, respectively. The latter species, stable in the solid state, was structurally characterized by diffraction methods and showed tetrahedral coordination of the Cu(I) ion
Metal imidazolato polymers: synthesis, characterization and crystal structure of new silver(I) triphenylphosphine derivatives
No full textWhen the polymeric complex [Ag(im)]n (Him = imidazole) is reacted with PPh3 (PPh3 = triphenylphosphine), it yields the [Ag2(mu2-im)2(PPh3)3] and [Ag(mu2-im)(PPh3)2]n species, shown to contain wavy chains of metal ions, singly bridged by N,N'-exobidentate imidazolate ligands. The former, crystallised as the CH2Cl2 solvate, contains two non-equivalent silver(I) ions, differing in the number of coordinated phosphines (one, in trigonal planar stereochemistry, or two, having tetrahedral geometry). The latter has a unique independent silver(I) ion in a tetrahedral environment, with two coordinated PPh3 ligands. The reactivity of known silver(I) azolates with PPh3, as well as the solution behaviour and (when available) the crystal structures of the corresponding derivatives are taken into consideration for a due comparison
- …
