Search results for "Complexes"
showing 10 items of 875 documents
Copper(I) Complexes of Bis(2-(diphenylphosphino)phenyl) Ether: Synthesis, Reactivity, and Theoretical Calculations
2007
The tricoordinated cationic Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(kappa(1)-P-DPEphos)][BF4] (1) (DPEphos = bis(2-(diphenylphosphino)phenyl) ether) containing a dangling phosphorus center was synthesized from the reaction of [Cu(CH3CN)(4)][BF4] with DPEphos in a 1:2 molar ratio in dichloromethane. When complex 1 is treated with MnO2, elemental sulfur, or selenium, the uncoordinated phosphorus atom undergoes oxidation to form a PE bond resulting in the formation of complexes of the type [Cu(kappa(2)-P,P'-DPEphos)(kappa(2)-P,E-DPEphos-E)][BF4] (2, E = O; 3, E = S; 4, E = Se) containing a Cu-E bond. The zigzag polymeric Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(mu-4,4'-bpy)](n)[BF4](n) (5) was …
Tungsten(VI) complexes formed in an excess of gluconic acid: A polarimetric and spectrophotometric study
1985
The tungsten(VI)-gluconic acid system in an excess of this organic reagent has been spectroscopically and polarimetrically studied and four species, two mononuclear with stoichiometry 1∶2 (metal∶ligand) and two dinuclear with composition 2∶2, have been identified. The non-formation of a binuclear species with stoichiometry 2∶1 (metal∶ligand) demonstrates some preference towards coordination of carboxylate group.
High oxidation state aqueous organometallics: synthesis and structure of a dinuclear oxo(pentamethylcyclopentadienyl)acetato complex of molybdenum(IV…
2003
International audience; The zinc reduction of Cp*2Mo2O5 in a MeOH–H2O mixture in the presence of acetic acid affords the diamagnetic dinuclear compound [Cp*MoO(O2CCH3)]2. An X-ray structural investigation reveals a novel dioxo- and diacetato-bridged structure, with a relatively strong metal–metal bond [2.5524(3) Å]. The compound exhibits a reversible one-electron oxidation process in the cyclic voltammogram. A comparison with other related structures reveals the effect of the electric charge on the mononuclear or dinuclear structural choice.Zinc reduction of Cp*2Mo2O5 in water–methanol in the presence of acetic acid affords compound Cp*2Mo2O2(O2CCH3)2, whose dinuclar tetrabridged structure …
Isomerism of [64Cu-NOTA-Bn]-labeled radiotracers: separation of two complex isomers and determination of their interconversion energy barrier using i…
2011
The model complex [(64)Cu((S)-p-NH(2)-Bn-NOTA)](-) ([(64)Cu]1) was used to study the isomerism of [(64)Cu-NOTA-Bn]-labeled radiotracers. Two complex isomers [(64)Cu]1a and [(64)Cu]1b, which were formed at a ratio of 1:9 during the complexation of [(64)Cu]Cu(2+) with (S)-p-NH(2)-Bn-NOTA, were separated using ion pair chromatography. To study the interconversion, the nonradioactive complex isomers Cu1a and Cu1b were separated and thermally treated at 90 °C in both ammonium acetate solution and deionized water. A faster interconversion rate was observed for both isomers with lower concentrations of ammonium ions. At the end of reaction, the thermodynamic Cu1a to Cu1b equilibrium ratio was 6:94…
Weak alkali and alkaline earth metal complexes of low molecular weight ligands in aqueous solution
2008
This work is aimed at reviewing the chemical literature dealing with thermodynamic aspects of the weak complex formation (species with log K values less than about 3) between alkali and alkaline earth metal ions with low molecular weight inorganic and organic ligands in aqueous solution. The following ligands (up to hexavalent anions) were examined in detail: (i) hydroxide, chloride, sulfate, carbonate and phosphate as inorganic, and (ii) carboxylates, amines, amino acids, complexones and nucleotides as organic ligands. The paper also identifies the main reasons responsible for the dispersion of the stability data on ion pairs in the literature. When possible, the trend of stability for the…
Luminescent Ionic Transition-Metal Complexes for Light-Emitting Electrochemical Cells
2012
Higher efficiency in the end-use of energy requires substantial progress in lighting concepts. All the technologies under development are based on solid-state electroluminescent materials and belong to the general area of solid-state lighting (SSL). The two main technologies being developed in SSL are light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs), but in recent years, light-emitting electrochemical cells (LECs) have emerged as an alternative option. The luminescent materials in LECs are either luminescent polymers together with ionic salts or ionic species, such as ionic transition-metal complexes (iTMCs). Cyclometalated complexes of Ir(III) are by far the most util…
Bright Blue Phosphorescence from Cationic Bis-Cyclometalated Iridium(III) Isocyanide Complexes
2012
We report new bis-cyclometalated cationic indium(III) complexes [((CN)-N-boolean AND)(2)Ir(CN-tert-Bu)(2)](CF3SO3) that have tert-butyl isocyanides as neutral auxiliary ligands and 2-phenylpyridine or 2-(4'-fluoropheny1)-R-pyridines (where R is 4-methoxy, 4-tert-butyl, or 5-trifluoromethyl) as (CN)-N-boolean AND ligands. The complexes are white or pale yellow solids that show irreversible reduction and oxidation processes and have a large electrochemical gap of 3.58-3.83 V. They emit blue or bluegreen phosphorescence in liquid/solid solutions from a cyclometalating-ligand-centered excited state. Their emission spectra show vibronic structure with the highest-energy luminescence peak at 440-…
Intramolecular electron transfer between molybdenum and iron mimicking bacterial sulphite dehydrogenase
2014
Diferrocenyl/diferrocenium substituted dioxido molybdenum(VI) complexes [Fe2MoO2] 2(Fc)/[2(FC)]²⁺ mimic the catalytic active site including the redox subunits as well as the catalytic function of bacterial sulphite oxidases.
Regulatory O 2 tensions for the synthesis of fermentation products in Escherichia coli and relation to aerobic respiration
1997
In an oxystat, the synthesis of the fermentation products formate, acetate, ethanol, lactate, and succinate of Escherichia coli was studied as a function of the O2 tension (pO2) in the medium. The pO2 values that gave rise to half-maximal synthesis of the products (pO0. 5) were 0.2-0.4 mbar for ethanol, acetate, and succinate, and 1 mbar for formate. The pO0.5 for the expression of the adhE gene encoding alcohol dehydrogenase was approximately 0.8 mbar. Thus, the pO2 for the onset of fermentation was distinctly lower than that for anaerobic respiration (pO0.5/= 5 mbar), which was determined earlier. An essential role for quinol oxidase bd in microaerobic growth was demonstrated. A mutant de…
A DFT mechanistic study of the synthesis of trans-Z,Z-[PtIICl(NH3){HN = C(NH2)Me}2]Cl from addition of NH3 to trans-[PtIICl2(N CMe)2]
2020
Abstract The reaction mechanism between trans-[PtIICl2(N CMe)2] and ammonia to give trans-Z,Z-[PtIICl(NH3){HN = C(NH2)Me}2]Cl has been studied at DFT level. Results showed that, in dichloromethane solution at 263.15 K, the chloride substitution by the ammonia on platinum is a process kinetically more favoured than the ammonia nucleophilic addition to the nitrile of about three orders of magnitude, and hence the nucleophilic addition reaction occurs after. Finally, both nucleophilic addition steps are geometrically driven to give products in the E configuration even if the final products were experimentally observed in the Z configuration. For trans-Z,Z-[PtIICl(NH3)(N CMe)2, the isomerizatio…