Search results for "Halide"
showing 10 items of 324 documents
Gold-Catalyzed Suzuki Coupling of ortho -Substituted Hindered Aryl Substrates
2017
International audience; A method that allows hindered ortho-substituted aryl iodides to be efficiently coupled to phenylboronic acid using a gold-catalyzed C-C bond formation is presented. The use of a molecularly-defined dinuclear gold chloride catalytic precursor that is stabilized by a new tetradentate (N,N')-diamino-(P,P')-diphosphino ferrocene hybrid ligand in a Suzuki-type reaction is described for the first time. Electron-rich isopropyl groups on phosphorus were found essen-tial for a superior activity, while the performances of a set of analogous gold dinuclear complexes that were fully characterized by multinuclear NMR spectroscopy and XRD analysis, were investigated. Therefore, ar…
In situ transmission electron microscopy study of electron beam-induced transformations in colloidal cesium lead halide perovskite nanocrystals
2017
An increasing number of studies have recently reported the rapid degradation of hybrid and all-inorganic lead halide perovskite nanocrystals under electron beam irradiation in the transmission electron microscope, with the formation of nanometer size, high contrast particles. The nature of these nanoparticles and the involved transformations in the perovskite nanocrystals are still a matter of debate. Herein, we have studied the effects of high energy (80/200 keV) electron irradiation on colloidal cesium lead bromide (CsPbBr3) nanocrystals with different shapes and sizes, especially 3 nm thick nanosheets, a morphology that facilitated the analysis of the various ongoing processes. Our resul…
Electrocarboxylation of Benzyl Halides through Redox Catalysis on the Preparative Scale
2006
The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogeneous charge-transfer catalysis was investigated both theoretically and experimentally to determine the influence of the operative parameters on the yield of the process and on the catalyst consumption. Theoretical considerations, based on fast kinetics of redox catalysis, were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane catalyzed by 1,3-benzenedicarboxylic acid di methyl ester performed at a carbon cathode under different operative conditions. We obtained high yields of the target carboxylic acid and experienced a low catalyst consumption by operating with optimized [RX]bulk/…
Reactivity of lithium β‑ketocarboxylates: the role of lithium salts
2017
Lithium beta-ketocarboxylates 1(COOLi), prepared by the reaction of lithium enolates 2(Li+) with carbon dioxide, readily decarboxylate in THF solution unless in the presence of lithium salts, in which case they are indefinitely stable at room temperature in inert atmosphere. The availability of stable THF solutions of lithium beta-ketocarboxylates 1(COOLi) in the absence of carbon dioxide allowed reactions to take place with nitrogen bases and alkyl halides 3 to give alpha-alkyl ketones 1(R) after acidic hydrolysis. The sequence thus represents the use of carbon dioxide as a removable directing group for the selective monoalkylation of lithium enolates 2(Li+). The roles of lithium salts in …
Ion Pair Binding in the Solid-State with Ditopic Crown Ether Uranyl Salophen Receptors
2016
Two ditopic uranyl salophen receptors with benzo-15-crown-5 and benzo-18-crown-6 units (R(1) and R(2), respectively) have been synthesized from commercially available starting materials. Comprehensive studies on the solid-state ion pair complexation with various alkali and ammonium halides have been conducted. From the 19 obtained solid-state structures (6 structures with R(1), 13 structures with R(2)), three general interaction motifs I-III have been observed. Interaction motif I has a separated ion pair with the cation coordinated to the crown ether unit, and the anion or oxygen containing solvent molecule coordinated to the uranyl center. The interaction motif II manifests a polymeric st…
Host–Guest Interactions of Sodiumsulfonatomethyleneresorcinarene and Quaternary Ammonium Halides: An Experimental–Computational Analysis of the Guest…
2020
The molecular recognition of nine quaternary alkyl- and aryl-ammonium halides (Bn) by two different receptors, Calkyl-tetrasodiumsulfonatomethyleneresorcinarene (An), were studied in solution using...
Ion pair complexes and anion binding in the solution of a ditopic receptor.
2016
The synthesis and crystal structures with alkali halides of a ditopic benzo-15-crown-5 bis-urea receptor have been presented. In addition, the anion binding properties of and its alkali metal complexes in solution are presented. A comprehensive single-crystal X-ray crystallographic study of , all together 13 crystal structures, including the ion pair complexes with NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, and RbI, give a detailed view of how behaves in the solid-state with different alkali halides depending on the size of the cation and anion. In the solid-state forms a 1 : 1 complex with a sodium cation and the anion is complexed as a contact (NaCl) or a separate ion pair (NaBr, NaI).…
Zirconocene-Based Methods for the Preparation of BN-Indenes : Application to the Synthesis of 1,5-Dibora-4a,8a-diaza-1,2,3,5,6,7-hexaaryl-4,8-dimethy…
2017
A method for the preparation of 3-bora-9aza-indene heterocycles based on zirconocene mediated functionalization of the ortho-CH bonds of pyridines has been developed and used to make two such compounds. Unlike other methods, the boron center in these heterocycles remains functionalized with a chloride ligand and so the compounds can be further elaborated through halide abstraction and reduction. The utility of the method was further demonstrated by applying it towards the preparation of 1,5- dibora-4a,8a-diaza BN analogues of the intriguing hydrocarbon s-indacene starting from 2,5-dimethylpyrazine. Gram quantities of one such compound was prepared and fully characterized, and both experimen…
Spatially ordered surfactant assemblies in the gas phase: negatively charged bis(2-ethylhexyl)sulfosuccinate-alkaline metal ion aggregates
2009
The formation and structural features of negatively charged aggregates of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) surfactant molecules in the gas phase have been investigated by electrospray ionization mass spectrometry (ESI-MS) and density functional theory calculations. Mainly driven by the interactions of alkali metal ions both with the oxygen atoms of the sulfonate group and with the succinate moiety of the AOT− anion, spatially ordered supramolecular assemblies, characterized by an internal core composed of surfactant counterions and hydrophilic head groups surrounded by the surfactant alkyl chains pointing outwards, are formed. Calculations have shown that surfactant self-organ…
The influence of aromatic cations on the geometries of the Bi(III) halide polyhedra. Synthesis and crystal structures of quinolinium, isoquinolinium …
2001
Abstract The compounds [quinolinium]4[Bi2Cl10] (1), [isoquinolinium]4[Bi2Cl10].2H2O (2) and [8-hydroxyquinolinium]4[BiCl6]·Cl·2H2O (3) have been obtained by reacting bismuthate oxide and the appropriate base in HCl acid medium. The crystal structures of 1 and 2 consist of quinolinium and isoquinolinium cations, respectively, interacting through hydrogen bonding with [Bi2Cl10]4− dimers. The different degree of interactions in the two derivatives causes significant differences in the bond distances of the anions. The crystal structure of 3 is made of [BiCl6]3− and Cl− anions and 8-hydroxyquinolinium cations. Hydrogen bond interactions including the N-bonded and O-bonded H atoms together with …