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MeCN Solution (mecn + solution)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Self-Assembled Two-Dimensional Water-Soluble Dipicolinate Cu/Na Coordination Polymer: Structural Features and Catalytic Activity for the Mild Peroxidative Oxidation of Cycloalkanes in Acid-Free Medium

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2008
Marina V. Kirillova
Abstract The new water-soluble 2D Cu/Na coordination polymer [Cu(,-dipic)2{Na2(,-H2O)4}]n·2nH2O (1) has been synthesized by self-assembly in aqueous medium from copper(II) nitrate, dipicolinic acid (H2dipic) and sodium hydroxide in the presence of triethanolamine. It has been characterized by IR spectroscopy, FAB+ -MS, elemental and single-crystal X-ray diffraction analyses, the latter featuring a layered 2D metal,organic structure that is extended to a 3D supramolecular assembly by extensive hydrogen bonding between adjacent layers and involving crystallization water molecules. Compound 1 has been shown to act as a catalyst precursor for the peroxidative oxidation of cyclohexane and cyclopentane to the corresponding cyclic ketones and alcohols by aqueous H2O2 in MeCN solution and in the absence of acid additives.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Construction of 1D and 2D Copper(I) Coordination Polymers Assembled by PhS(CH2)nSPh (n = 1, 2) Dithioether Ligands: Surprising Effect of the Spacer Length on the Dimensionality, Cluster Nuclearity and the Fluorescence Properties of the Metal,Organic Framework,

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007
Harmel N. Peindy
Abstract Treatment of CuI with PhSCH2SPh in MeCN solution affords, by a self-assembly reaction, the monodimensional metal,organic coordination polymer [Cu4I4{,-PhS2CH2SPh}2]n (1), in which Cu4(,3 -I)4 cluster units are linked by the dithioether ligand in a 1D necklace structure. In contrast, the reaction of PhSCH2CH2SPh with CuI results in the formation of the metallopolymer [(CuI)2{,-PhS(CH2)2SPh}2]n (2). The 2D network of 2 is built from dimeric Cu2I2 units which are connected by 1,2-bis(phenylthio)ethane bridging ligands. The solid-state luminescence spectrum of 1 exhibits a strong emission around 532 nm, whereas a weak emission centred at 413 nm is observed in the case of 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Pseudorotaxanes and Rotaxanes Formed by Viologen Derivatives

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2006
Adam B. Braunschweig
Abstract Dibenzyl-4,4,-bipyridinium (BIPY2+) bis(hexafluorophosphate) and three of its derivatives , disubstituted at the para positions of the benzyl groups with CO2Me, F, and Me in turn , have been shown to form 1:1 complexes that are [2]pseudorotaxanes with dibenzo[24]crown-8 (DB24C8), benzometaphenylene[25]crown-8 (BMP25C8), and dipyrido[24]crown-8 (DP24C8) in CD3CN solution by 1H NMR spectroscopy and in one case in the solid state by X-ray crystallography. Binding constants (Ka) for all of these 1:1 complexes, which were determined both (1) by isothermal titration calorimetry in MeCN solution and (2) by the 1H NMR spectroscopic single-point method in CD3CN solution, were found to be, on the average, an order of magnitude less than the Ka values obtained for DB24C8 and DP24C8 with dibenzylammonium (DBA+) hexafluorophosphate and three of its derivatives, also disubstituted at the para positions of the benzyl groups with CO2Me, F and Me. In the case of BMP25C8, however, the Ka values with both categories (BIPY2+ and DBA+) of guests are much of a muchness, being both small and error prone. The equilibrium thermodynamics for these small libraries of [2]pseudorotaxanes indicate that the best bistable [2]rotaxanes incorporating both DBA+ and BIPY2+ recognition sites are going to involve ester functions in their dumbbell components and will employ DP24C8 or, failing that, DB24C8 as the ring component. The BIPY2+threads also directed the templated assembly of [2]rotaxanes incorporating the crown ethers (DB24C8, DP24C8, and BMP25C8) and triphenylphosphonium stoppers using the threading followed by stoppering approach. The rotaxanes were characterized in solution by 1H NMR spectroscopy, and in one case, in the solid state by X-ray crystallography.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Stereoelectronic effects in radical processes,

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8-9 2006
Paolo Brandi
Abstract A kinetic study of the H-abstraction reaction from cyclic and acyclic alkylarene substrates by the nitroxyl radical (dubbed BTNO) of 1-hydroxy-benzotriazole (HBT) has been carried out in MeCN solution at 25°C. BTNO was generated from one-electron oxidation of HBT by cerium(IV) ammonium nitrate. The H-abstraction reactivity measured with the cyclic alkylarenes is invariably higher than that with the acyclic counterparts. This is explained as the contribution of hyperconjugation between the aromatic ,-system and the scissile benzylic CH bond of the substrate, which weakens the CH bond in the transition state and promotes its cleavage. Stereoelectronic considerations enable to appreciate why the weakening effect is more pronounced in the cyclic system than in the acyclic counterpart, thereby justifying the higher reactivity of the former. Evidence for the intervention of stereoelectronic effects is embodied by the dissociation energies of the CH bonds, having always lower values for the cyclic substrates investigated. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Polymorphism in iodotris(tri- p -tolylphosphine)silver(I)

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009
Gertruida J. S. Venter
The reaction of silver(I) iodide with tri(p -tolyl)phosphine in MeCN solution in 1:3 molar ratio yields a polymorph of the complex of the formula [AgI{P(4-MeC6H4)3}3], with the Ag atom in a distorted tetrahedral environment. A polymorphic structure of this complex (a) is compared with previously published crystal structures (b), determined at different temperatures. The two polymorphs are compared using r.m.s. overlay calculations as well as half-normal probability plots. [source]