Search results for "ion chemistry"
showing 10 items of 254 documents
Electroactive polymeric material with condensed structure on the basis of magnesium(II) polyporphine
2011
International audience; Previous publication of the authors presented evidences that electroch emical oxidation of Mg(II) porphine (fully unsubstituted porphyrin, MgP) in acetonitrile (AN) at a very low potential leads to deposition of films at electrode surface corresponding to typical electroactive polymers, with their reversible transition betwee n the electronconducting and insulating states depending on the electrode potential/oxidation level ("film of type I"). It is demonstrated in the actual publication that these films in contact with a monomer-free solution are subject to an irreversible transformation to quite a different material ("film of type II") under the influence of a high…
Cobalt complex based on cyclam for reversible binding of nitric oxide
2008
We report the synthesis and theoretical calculations of nitrosyl cobalt complexes based on saturated tetraazamacrocycle for the reversible binding of nitric oxide (NO). Density-functional theory provides a rigorous theoretical framework for analysing, interpreting and investigating important parameters in order to further tune the properties of these complexes to the target application. We focus on understanding the stability of complexes in methanol solution as well as their reactivity and stability evolution in the presence of NO, O2 and higher nitrogen oxides intermediates. Calculations have been used to explore appropriate combinations of different macrocycles, metal centres and ligands…
Carbon dioxide conversion to dimethyl carbonate: The effect of silica as support for SnO2 and ZrO2 catalysts
2011
International audience; Abundant in nature, CO2 poses few health hazards and consequently is a promising alternative to phosgene feedstock according with the principles of Green Chemistry and Engineering. The synthesis organic carbonates from CO2 instead of phosgene is highly challenging as CO2 is much less reactive. As part of our ongoing research on the investigation of catalysts for dimethyl carbonate (DMC) synthesis from methanol and CO2, we herein report results aimed at comparing the catalytic behavior of new SnO2-based catalysts with that of ZrO2. Silica-supported SnO2 and ZrO2 exhibit turnover numbers which are an order of magnitude higher than those of the unsupported oxides. Tin-b…
First donor stabilized-phosphenium rhodium complexes
2008
Abstract The coordination properties of a donor stabilized-phosphenium adduct have been examined in rhodium chemistry. The preparation as well as the characterization of the first examples of donor stabilized-phosphenium rhodium(I) complexes is reported in this paper. Indeed, mono- and di-cationic rhodium complexes were obtained in quantitative yield by the direct addition of this imidazolium P(III)-ligand to [RhCl(1,5-COD)] 2 in CH 2 Cl 2 solution with a 1:1 P/Rh ratio under argon and 2:1 P/Rh ratio under CO atmosphere, respectively. Crystal structure of the bis-cationic donor stabilized-phosphenium rhodium(I) complex has been obtained from an acetone/pentane mixture. Its molecular structu…
Monitoring the hydrogen bond net configuration and the dimensionality of aniline and phenyloxamate by adding 1 H -pyrazole and isoxazole as substitue…
2019
This work describes the synthesis and characterization of a new class of oxamic acid derivatives containing pyrazole and isoxazole as substituents to investigate their ability to form hydrogen bonds aiming at applying them in crystal engineering and molecular self-recognition. In this respect, we report a new synthesis of 2-(4-nitrophenyl)-1,3-propanedial (1) in high yield using SOCl2 as a chlorinating agent. The new oxamic esters 4-(1H-pyrazol-4-yl)phenylene-N-(ethyloxamate) (2d) and 4-(1,2-oxazol-4-yl)phenylene-N-(ethyloxamate) (3d) were prepared from 1. The synthetic route consists of the cyclisation of 1 either with hydrazine to afford 4-(-aminophenyl)-1H-pyrazole (2a) or with hydroxyla…
Crystal structure of the tetraaquabis(thiocyanato-kappa N)cobalt(II)-caffeine-water (1/2/4) co-crystal
2017
In the structure of the title compound, [Co(NCS)2(H2O)4]·2C8H10N4O2·4H2O, the cobalt metal lies on an inversion centre and is coordinated in a slightly distorted octahedral geometry. In the crystal, the complex molecules interact with the caffeine molecules through O—H⋯N, O—H⋯O, C–H⋯S hydrogen bonds and π–π interactions.
Hydrogen bonding and proton transfer involving the trihydride complexes Cp*M(dppe)H 3 (M = Mo, W) and fluorinated alcohols: the competitive role of t…
2003
International audience; The protonation of complexes Cp*M(dppe)H3 (dppe is ethylenebis(diphenylphosphine), M = Mo (1), W (2)) by a variety of fluorinated alcohols of different acid strength (FCH2CH2OH, CF3CH2OH, (CF3)2CHOH, and (CF3)3COH) was investigated experimentally by the variable temperature spectroscopic methods (IR, NMR) and stopped-flow technique (UV-Vis). The structures of the hydrogen-bonded and proton transfer products were studied by DFT calculations. In agreement with the calculation results, the IR data suggest that the initial hydrogen bond is established with a hydride site for complex 1 and with the metal site for complex 2. However, no intermediate dihydrogen complex foun…
Resolution of β-aminophosphines with chiral cyclopalladated complexes
2005
Abstract Resolution of the racemic chiral β-aminophosphines Ph 2 PCH 2 CH(Ph)NH(Ar) ( L 1 for Ar = C 6 H 5 and L 2 for Ar = 2,6-C 6 H 3 i Pr 2 ) has been investigated by use of different cyclopalladated complexes as chiral agents. The resulting complexes afford diastereomeric adducts in a 1:1 ratio. After successive crystallizations from ethanol, a d.e. of 98% was achieved for one aminophosphine palladium complex, while no significant d.e. was obtained after crystallizations from chlorinated solvents. The X-ray structure analysis has pointed out intermolecular hydrogen interactions N–H⋯Cl between the P,N ligand and the chloride ion, which are responsible for the formation and stabilization …
ChemInform Abstract: Solution Chemistry of Element 106: Theoretical Predictions of Hydrolysis of Group 6 Cations Mo, W, and Sg.
2001
Preparation and structure of the 17-electron (η5-C5R5)Mo(OH)2(dppe) (R=Me, Et) organometallic compounds containing two gem-terminal hydroxide ligands
2000
International audience; Oxidation of (η5-C5R5)MoH3(dppe) (R=Me, Et) by Cp2Fe+ in wet THF leads to the formation of the corresponding (η5-C5R5)Mo(OH)2(dppe). These compounds show a low-potential reversible oxidation wave. The structure of the C5Et5 complex has been confirmed by X-ray diffraction methods: triclinic; space group ; a=11.030(1); b=12.533(1); c=16.241 (1) Å; α=68.585(7); β=75.197(5); γ=83.991(7)°; V=2020.6(3) Å3; Z=2; Dcalc=1.324 g cm−3, μ(Mo–Kα)=0.441 mm−1; R1=0.0325; wR2=0.0875 for 415 parameters and 6823 independent reflections [Rint=0.0177] with I=2σ(I). The molecule shows a four-legged piano-stool geometry with two terminal OH ligands in a relative trans configuration. The c…