1,721,173 research outputs found
Solvent effects on the redox potential of the uranium(VI)?uranium(V) couple
No full textBinary and ternary systems involving adenosine 5′-triphosphate (ATP), 2,2′-dipyridylamine (DPA) and magnesium, calcium, strontium, manganese, cobalt, copper, and zinc(II) metal ions have been investigated in aqueous media by potentiometric titrations. The analysis of the titration curves shows the existence of M(ATP)2−, M(ATP)(H)−, and M(ATP)2(H)24− species for alkaline-earth metal ions, while no ternary complex can be detected. For transition metal ions both binary and ternary species are found. Binary M(ATP)2(H)24− complexes are present in solutions containing manganese and cobalt(II) metal ions but these species cannot be revealed in the case of copper and zinc(II). Ternary complexes as M(ATP)(DPA)2− and M(ATP)(DPA)(H)− are common to all transition metals. Binuclear and hydroxo complexes as M2(ATP)(OH)− and M(ATP)(OH)3− are found only for copper and zinc(II). A hypothesis on the possible role of the species M-ATP in 1:2 ratio in the dephosphorylation mechanism is advanced on the basis of a comparison between the equilibrium data in the solution phase and the solid state structures of the magnesium, calcium, and manganese(II)- ATP-DPA systems
Electrochemical behaviour ofcis-dichloro(arylisocyanide)(tertiaryphosphine) platinum (II) and palladium(II) complexes in an aprotic solvent
No full textThe electrochemical behaviour of neutral platinum(II) and palladium(II) isocyanide complexes has been investigated in an aprotic medium at platinum and mercury electrodes. Platinum(II) derivatives are reduced to platinum(0) species, Palladium(II) compounds give rise to palladium(0) species at room temperature, while at 0° it is possible to obtain palladium(I) compounds
Electrochemical synthesis of the N,N′-ethylenebis-(monothioacetylacetominiminato)cobalt(II), copper(II), nickel(II) and zinc(II) complexes
No full textCobalt(II), copper(II), nickel(II) and zinc(II) complexes are synthesised via electrochemistry, by anodic polarisation of the corresponsding metal in a solution containing the ligand. The resulting complexed are then purified and characterised
Electrochemical investigations of cationictrans-haloarylisocyanidebis(tertiaryphosphino)platinum (II) complexes
No full textThe electrochemical behaviour of a series of cationic platinum(II) isocyanide complexes has been studied in acetonitrile. All the tested compounds are oxidized at a platinum electrode via a two-electron process and reduced at a platinum or mercury electrode via two successive one-electron steps. The anodic step involves the formation of platinum(IV) complexes. The main reduction product formed in correspondence to the first cathodic process is a stable dimer platinum(I) containing bridging isocyanide ligands. Platinum(0) species are formed in the subsequent reduction step
Electrochemical investigation on the phosphine rhenium complexes [ReCl3(PMe2Ph)3] and [ReCl4(PMe2Ph)2] in an aprotic medium
No full textThe cathodic and anodic behaviour of the complexes [ReCl3(PMe2Ph)3] and [ReCl4(PMe2Ph)2] has been studied at platinum and mercury electrodes in acetonitrile solvent. The reduction and oxidation products have been identified and both thermodynamic and kinetic aspects of the involved electrode mechanisms have been studied. In particular, new rhenium derivatives such as [ReCl3(PMe2Ph)3]+. [ReCl4(PMe2Ph)2]− and [ReCl3(PMe2Ph)2(MeCN)]+, have been prepared. In addition the species [ReCl4(PMe2Ph)2] has been obtained in a yield higher than that obtained by conventional chemical methods. The EView the MathML source values of several redox couples of rhenium complexes have been calculated and compared with the corresponding values of the technetium ones; the stability of analogous rhenium and technetium compounds has been also discussed
Conoscere la Chimica. Fondamenti di Chimica Generale e Inorganica con elementi di Organica
No full textVoltammetric investigations on mercury(II) and silver(I) polyamine complexes in dimethyl sulphoxide solution
No full texthe formation of mercury(II) and silver(I) complexes with polyamines in dimethyl sulphoxide solvent has been studied by anodic dissolution of mercury and silver electrodes in the presence of ethylenediamine, sym-dimethyl-ethylenediamine, NNN′N′-tetramethylethylenediamine, propane-1,3-diamine, and triethylenetetramine. D.c. polarography at a dropping mercury electrode, d.c. voltammetry at a solid electrode with periodical renewal of the diffusion layer, cyclic voltammetry, and controlled-potential coulometry has allowed a determination of electrode reaction orders, the complexation steps, and the stability constants of the complex species arising at the electrode surface. Short-lived species have been detected by cyclic voltammetry and the species formed in the bulk of the solution have been identified by coulometry
The standard redox potential in the study of solute—solvent interactions. Dirhodium complexes
No full textA wide series of empirical parameters of solvents are employed in the study of the dependence of the redox potentials of some dirhodium(II) derivatives [namely, Rh2(O2CCF3)2(form)2, Rh2(form)4, Rh2(ONHCF3)4] upon the solvent nature. A statistical approach is proposed which analyzes the influence of solvent basicity, acidity and polarizability both independently and jointly. This has proved to be useful in rationalizing the solvent effects on the redox potentials, as well as in suggesting different solvation models
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