1,721,137 research outputs found
Synthesis and characterization of trigonal-bipyramidal platinum(II) olefin complexes with chalcogenide ligands in axial positions. X-ray molecular structures of [Pt(SMe)(2)(dmphen)(diphenyl fumarate)], its cationic dipositive derivative [Pt(SMe2)(2)(dmphen)(diphenyl fumarate)][BF4](2), and free diphenyl fumarate
No full textThe oxidative addition of RE-ER molecules (E = O, R = H, C(O)Ph, C(O)Me; E = S, Se, Te, R = Me, Ph) to Pt(0) precursors [Pt(N,N-chelate)(olefin)] (1: N,N-chelate = e.g. 2,9-dimethyl-1,10-phenanthroline; olefin = maleic or fumaric ester) has been studied. Symmetrical cleavage of the E-E bonds affords unprecedented trigonal-bipyramidal Pt(II) complexes of the formula [Pt(ER)2(N,N-chelate)(olefin)] (2). Products of type 2, which have been characterized through H-1 and C-13 NMR spectroscopy, contain chalcogenide ligands in the axial positions. The reactivity of the new compounds has also been investigated. Thus, Pt-OH fragments generated by the addition of H2O2 are acetylated by acetic anhydride. Furthermore, S, Se, and Te coordinated to Pt are readily methylated by trimethyloxonium tetrafluoroborate, affording the first examples of dipositive coordinatively saturated platinum(11) cations (3). The structures of the related neutral [Pt(SMe)(2)(2,9-dimethyl-1,10-phenanthroline)(diphenyl fumarate)] and cationic [Pt( Me2)(2)(2,9-dimethyl-1,10-phenanthroline)(diphenyl fumarate)] [BF4](2) compounds have been determined by X-ray diffraction together with that of the free diphenyl fumarate ligand. RI Monari, Magda/B-2648-200
Sensitivity of a solid Eu(III) complex towards acetonitrile vapor: Structural and spectroscopic characterization
No full textThe Eu(III) nitrate complex of the meso- N,N'-bis(2-pyridylmethylene)-1,2-(R,S)-cyclohexanediamine ligand was synthesized and characterized by single crystal and powder X-ray diffraction. The crystal lattice of the complex is capable of absorbing and desorbing selectively acetonitrile molecules, at 293 K upon an acetonitrile vapor pressure of similar to 0.1 x 10(5) Pa. This process, which is partially reversible, can be easily followed by both powder X-ray diffraction (P-XRD) and Eu(III) luminescence spectroscopy. The acetonitrile molecule, located in the outer coordination sphere of the metal ion, does not affect the radiative transition probability of D-5(0) level of Eu(III) and also it does not activate further non-radiative channels from this level. On the other hand, this molecule is capable of affecting the energy position and intensities of the crystal field components of the D-5(0) -> F-7(2) transition. The complex in solid form can be considered a promising material for the optical sensing of acetonitrile vapors
Synthesis and Structural Characterizations of New Coordination Polymers Generated by the Interaction Between the Trinuclear Triangular SBU [Cu 3 (μ 3 -OH)(μ-pz) 3 ] 2+ and 4,4′-Bipyridine. 3°
No full textThe reactions of 4,4′-bipyridine with selected trinuclear triangular copper(II) complexes, [Cu3(μ3-OH)(μ-pz)3(RCOO)2Lx], [pz = pyrazolate anion, R = CH3(CH2)n (2 ≤ n ≤ 5); L = H2O, MeOH, EtOH] yielded a series of 1D coordination polymers (CPs) based on the repetition of [Cu3(μ3-OH)(μ-pz)3] secondary building units joined by bipyridine. The CPs were characterized by conventional analytical methods (elemental analyses, ESI-MS, IR spectra) and single crystal XRD determinations. An unprecedented 1D CP, generated through the bipyridine bridging hexanuclear copper clusters moieties, two 1D CPs presenting structural analogies, and two monodimensional tapes having almost exactly superimposable structures, were obtained. In one case, the crystal packing makes evident the presence of small, not-connected pores, accounting for ca. 6% of free cell volume
Taming gold(I)-counterion interplay in the de-aromatization of indoles with allenamides
No full textA careful interplay between the π electrophilicity of a cationic Au I center and the basicity of the corresponding counterion allowed for the chemo- and regioselective inter- as well as intramolecular de-aromatization of 2,3-disubstituted indoles with allenamides. The silver-free bifunctional Lewis acid/Brønsted base complex [{2,4-(tBu)2C 6H3O}3PAuTFA] assisted the formation of a range of densely functionalized indolenines under mild conditions
Ru(bpy)2Cl2: a catalyst able to shift the course of the photorearrangement in the Boulton–Katritzky reaction.
No full textThe Boulton-Katritzky reaction represents one of the most popular and efficient strategies used to realize azole-into-azole conversions. For example, under different experimental conditions, it allows the rearrangement of Z-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazoles (1) into 2-aryl-4-benzoylamino-5-phenyl-2H-1,2,3-triazoles (2) in very high yields. Moreover, we have recently realized this conversion also by UV-photostimulation. Now we have enlarged the scope of the reaction irradiating with visible or UV light an acetonitrile solution of some Z-arylhydrazones (1a-e) in the presence of catalytic amounts of Ru(bpY)(2)Cl-2. We have observed the unexpected formation of the 1-aryl-5-benzoylamino-3-phenyl-1,2,4-triazoles (3a-e) eventually together with the expected 2a-d in high yields
1D and 3D coordination polymers based on the Cu-3(mu(3)-OH)(mu-pz)(3) and Cu(Hpz)(3) SBUs connected by the flexible glutarate dianion
No full textDifferent synthetic procedures lead to different coordination polymers (CPs) based either on the trinuclear triangular [Cu3(μ3-OH)(μ-pz)3]2+ or on the mononuclear [Cu(Hpz)3]2+ (Hpz = pyrazole) secondary building units (SBUs), bridged by the flexible glutarate (Glu) dianion. The mononuclear complex [Cu(HGlu)2(Hpz)4] was also obtained as byproduct. One of the CPs based on the trinuclear SBU displays a relevant porosity due to three intersecting channels, accounting for about 40% of the solvent accessible void space
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
Synthesis, cytotoxicity and anti-cancer activity of new alkynyl-gold(I) complexes
Full text linkAlkynyl(triphenylphosphine)gold(I) complexes carrying variously substituted propargylic amines have been synthesized and fully characterized in solution and solid state. High levels of toxicity (i.e. micromolar range) were recognized for a series of cancer cell lines with particular emphasis on HT29, IGROV1, HL60 and I407. In particular the lead compound 3ab was identified as the most active compound in all cell lines (IC50: 1.7–7.9 μM)
Absolute configuration, coordination and stereochemical influence of 1,3,5,7-tetramethyl-2,6,9-trioxo-bicyclo[3,3,1]nona-3,7-diene in Rh(I) and cationic Pd(II) complexes
No full textRelevant stereochemical and coordination features of 1,3,5,7-tetramethyl-2,6,9-trioxo-bicyclo[3,3,1]nona-3,7-diene (TOND), a chiral molecule of C-2 symmetry are described. The X-ray crystal structure of [RhCl{(S)-CHPhMeNH2}{(+)-TOND}] has ascertained that the absolute configuration of (+)-TOND is R,R. Furthermore, the synthesis of stable cationic Pd(II) pi-allyl complexes of general formula [Pd(eta(3)-allyl)(TOND)][BF4] has allowed to probe the ability of this ligand to afford stereoselective coordination of prochiral fragments. The X-ray molecular structure of the representative compound [Pd(eta(3)-crotyl)(TOND)][BF4] has been determined. Finally, the influence of TOND on the stereochemistry of prochiral nitrogen donors of diamine and phosphamine chelates has been explored in rhodium complexes of general formula [Rh(chelate)(TOND)][BF4]. The configurations of the nitrogen donors have resulted as stereospecifically selected by the presence of TOND. (C) 2003 Elsevier B.V. All rights reserved
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