Search results for "material"
showing 10 items of 32550 documents
Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand : Synthesis, characterization and oxotransfer activity
2020
Abstract Reaction of [MoO2Cl2(dmso)2] with the tetradentate O2N2 donor ligand papy [H2papy = N-(2-hydroxybenzyl)-N-(2-picolyl)glycine] leads to formation of the dioxomolybdenum(VI) complex [MoO2(papy)] (1) as a mixture of cis and trans isomers. Recrystallization from methanol furnishes solid cis-1, whereas the use of a dichloromethane-hexane mixture allows for the isolation of the trans-1 isomer. Both isomers have been structurally characterized by X-ray crystallography and the energy difference between the isomeric pair has been investigated by electronic structure calculations. Optimization of two configurational isomers in the gas phase predicts the trans isomer to lie 2.5 kcal/mol lower…
Vinyl sulfone building blocks in covalently reversible reactions with thiols
2015
In the present study we use quantum-chemical calculations to investigate how the reactivity of vinyl sulfone-based compounds can be modified from an irreversible to a reversible reaction with thiols. Based on the predictions from theory, an array of nine different vinyl sulfones with systematically varying substitution pattern was synthesized and their crystal structures were determined. Subsequent Hirshfeld surface analyses employing the principle of electrostatic complementarity aid the understanding of the crystal packing of the synthesized compounds. Reactivity studies against the nucleophile 2-phenylethanethiol mirror the properties predicted by the quantum-chemical computations in sol…
Bis(2-methylbenzimidazole-κN1)copper(I) dichlorocuprate(I)
2004
By using alternating-current electrochemical synthesis, crystals of the copper(I) ionic compound composed of [Cu(C8H8N2)2]+ and [CuCl2]− ions have been obtained and structurally investigated. Both crystallographically independent Cu atoms lie on centres of inversion and exhibit the less-common coordination number 2. A linear arrangement of the metal atoms includes two N atoms of the different organic moieties in the [Cu(2-methylbenzimidazole)2]+ cation and two Cl atoms in the case of the inorganic anion.
Insight into the Mechanism of Water Adsorption/Desorption in Hydrophilic Viologen-Carboxylate Based PCP
2017
A water stable and highly hydrophilic porous coordination polymer based on viologen-carboxylate type ligand, the 4,4′-bipyridinium,1,1-bis(3-carboxyphenyl) (pc2), is obtained by the solvothermal method: [Cd3(pc2) (BTC)2(H2O)2]·6H2O ([1(H2O)2]·6H2O; BTC3– = 1,3,5-carboxybenzene). Its crystal structure and the ones of two partially dehydrated phases have been determined, allowing insight into the mechanism of water adsorption/desorption of this PCP material. It is shown that the dehydrated compound [1] first adsorbs two water molecules which fill the pores, leading to [1]·2H2O. On the other hand, the partial dehydration of the as-synthesized compound leads to the intermediate phase [1(H2O)]·3…
A novel two-dimensional organostannoxane coordination network promoted by phenazine: Synthesis, characterization and X-ray structure of
2009
Abstract Reaction of the dimeric hydroxo di-n-butylstannane trifluoromethanesulfonato complex [n-Bu2Sn(μ-OH)(H2O)0.5(η1-O3SCF3)]2 (1) with phenazine (C12H8N2, Phz) (2) in dichloromethane at room temperature in a 1:3 molar ratio yielded the novel two-dimensional organometallic coordination polymer 2 ∞ { [ n - Bu 2 ( μ -OH ) SnOSn ( μ - η 2 - O 3 SCF 3 ) n - Bu 2 ] 2 [ n - Bu 2 ( μ -OH ) SnOSn ( η 1 - O 3 SCF 3 ) n - Bu 2 ] 2 } (3), together with the phenazinium trifluoromethanesulfonate salt [C12H9N2]+ [CF3SO3]−, crystallographically isolated in two different structural arrangements, free 4 and in π–π aromatic stacking interaction with independent intercalated non-protonated phenazine molecu…
A cyanide and hydroxo-bridged nanocage: a new generation of coordination clusters.
2013
International audience; Combining serendipitously-formed hydroxo-clusters, [CoII3(OH)(piv)4(L)]+ (where L = MeCN or Hpiv), with assembling cyanide building block, [FeIII(Tp)(CN)3]−, has led to an unprecedented architecture where polymetallic cobalt clusters and blocked tris-cyanide iron complexes define the apexes of a unique magnetic cubic nanocage.
Synthesis, crystal structures and magnetic properties of picolinate-bridged copper(II) chains
2018
The paper reports the synthesis, crystal structures, and magnetic properties of two copper(II) coordination polymers, Cu2(L1)4 (1) and Cu3(L2)6 (2), based on rigid ethynylene-bridged ditopic ligands containing one picolinate subunit (L1 = 5-(pyridin-3-ylethynyl)picolinate anion; L2 = 5-((4-(methoxycarbonyl)phenyl)ethynyl)picolinate anion). Both 1 and 2 have a chain structure. In 1, the repeating unit in the chain is a doubly bridged picolinate dicopper(II) complex, whereas 2 is built upon trimeric units where the Cu2+ ions are also connected by double picolinate bridges. Both compounds exhibit antiferromagnetic interactions in the solid state. The magnetic properties of 1 and 2 were analyze…
2-Methyltetrahydrofuran: A Green Solvent for Iron-Catalyzed Cross-Coupling Reactions
2018
Iron‐catalyzed cross‐coupling reactions allow sustainable formation of C−C bonds using cost‐effective, earth‐abundant base‐metal catalysis for complex syntheses of pharmaceuticals, natural products, and fine chemicals. The major challenge to maintain full sustainability of the process is the identification of green and renewable solvents that can be harnessed to replace the conventional solvents for this highly attractive reaction. Herein, iron‐catalyzed cross‐coupling of aryl chlorides and tosylates with challenging organometallic reagents possessing β‐hydrogens is found to proceed in good to excellent yields with the green, sustainable, and eco‐friendly 2‐methyltetrahydrofuran (2‐MeTHF) a…
Exploratory Synthesis of Low-Silica Nanozeolites through Geopolymer Chemistry
2019
Nanozeolites are of great interest with the premise of their efficiency in traditional applications such as catalysis and separation, as well as their emerging applications including chemical sensors, medicine, and food industry. We report a new geopolymerization route for the synthesis of nanozeolites with different crystal structures by exploring the Na–Al–Si–H2O quaternary phase space under a mild hydrothermal condition. Nanostructured faujasite (FAU), cancrinite (CAN), and sodalite (SOD) zeolites with a crystallite size smaller than 40 nm were successfully produced from our exploration, as well as a submicron-sized Linde-Type A (LTA) zeolite. The transmission electron microscopy and nit…
A Generalized Semiempirical Approach to the Modeling of the Optical Band Gap of Ternary Al-(Ga, Nb, Ta, W) Oxides Containing Different Alumina Polymo…
2021
A generalization of the modeling equation of optical band gap values for ternary oxides, as a function of cationic ratio composition, is carried out based on the semiempirical correlation between the differences in the electronegativity of oxygen and the average cationic electronegativity proposed some years ago. In this work, a novel approach is suggested to account for the differences in the band gap values of the different polymorphs of binary oxides as well as for ternary oxides existing in different crystalline structures. A preliminary test on the validity of the proposed modeling equations has been carried out by using the numerous experimental data pertaining to alumina and gallia p…