Metal ions and complexes

Click Coached Problems for a self-study module on solubility of metal ions and complex ion equilibria. 

Armstrong FA, Cox PA, Hill HAO, Lowe VJ, Ohver BN. 1987. Metal-ions and complexes as modulators of protein interfacial electron-transport at graphite-electrodes. J Electroanal Chem217 331-366. 

Several transition metal ions and complexes, especially Pd(II) salts, have been found to catalyze Cope rearrangements.207 The catalyst that has been adopted for synthetic purposes is PdCl2(CH3CN)2, and with it the rearrangement of 14 to 15 and 16 occurs at room temperature, as contrasted to 240° C in its absence.208 The catalyzed reaction shows enhanced stereoselectivity and is consistent with a chairlike TS. 

According to R. Brdicka and K. Vesely the carbonyl form of formaldehyde is reduced and the limiting kinetic current is given by the rate of the chemical volume reaction of dehydration. An analogous situation occurs for the equilibria among complexes, metal ions and complexing agents if the rates of complex formation and decomposition are insufficient to preserve the equilibrium. A simple example is the deposition of cadmium at a mercury electrode from its complex with nitrilotriacetic COO"... 

Many factors influence the deposition kinetics of P and B, including metal ion and complexant concentrations, solution pH, and temperature. Though unavoidable side products of the electroless deposits, P and B impart unique properties to electroless deposits, e.g., good corrosion resistance in the case of Ni-P deposits, where the P content can exceed 30 at% in certain solutions [10, 11],... 

Catalysis by Transition Metal Ions and Complexes in Hydrocarbon Oxidation by Dioxygen... 

CATALYSIS BY TRANSITION METAL IONS AND COMPLEXES IN HYDROCARBON OXIDATION BY DIOXYGEN... 

Rate Constants of the Reaction of Transition Metal Ions and Complexes with Hydroperoxides... 

Rate Constants of Free Radical Reactions with Transition Metal Ions and Complexes... 

Ketones are resistant to oxidation by dioxygen in aqueous solutions at T= 300-350 K. Transition metal ions and complexes catalyze their oxidation under mild conditions. The detailed kinetic study of butanone-2 oxidation catalyzed by ferric, cupric, and manganese complexes proved the important role of ketone enolization and one-electron transfer reactions with metal ions in the catalytic oxidation of ketones [190-194],... 

Hydrolysis of coordinated ligands is a special case of nucleophilic attack. Two examples involving inorganic ligands have already been given in Section II. A on aquation of cobalt(III) complexes. Many further examples will be found in the following Section VII.B on catalysis of hydrolysis of organic substrates by metal ions and complexes. 

Adsorption of Metal Ions and Complexes on Aluminosilicate Minerals... 

Interactions between adsorbed metal ions and complex organic molecules have been observed in other systems. For example, IR results Indicated that coraplexation occurred between sulfolane (C4 H8S02) and either Cu or NI montmorillonites, with the result that... 

Open-shell transition metal ions and complexes... 

II Ligand field effects (from unpaired electrons in transition metal ions and complexes) Phosphorescence, lasers... 

Although the oxidation of thiols to disulfides in the presence of a catalyst is a reaction of commercial interest, it is only comparatively recently that the marked effects of impurities on the system has been realized. Wallace and co-workers (13, 14) have studied the metal-catalyzed oxidation of some thiols in the presence of a few metal ions and complexes under comparable conditions, and they have suggested a general mechanism for the reaction, based on Reactions 1, 4, 5, 6, and 7. The rate of reaction was found to depend on the chemical nature and the physical state of the catalyst. The reaction was suggested to involve metal complexes in the solid state (13). 

Ab initio calculations using DFT have shown that the reactions which occur between artemisinin and some metal ions and complexes lead to a series of radicals which are probably responsible for its therapeutic activity. In particular, it has been shown that the interaction of Fe(ll) with artemisinin 9a causes the 0-0 bond to be broken, as do Fe(iii) and Cu(l), but not Zn(ll) <2004JST95>. DFT calculations have been carried out on the interactions of artemisinin and several other endoperoxides with the hexaaquaferrous ion [Fe(Fl20)6] and heme <2005JST87>. 

Owing to the large variety of surfactants, metal ions, and complex metal ions that have been incorporated into LB films, variations of the stoichiometry given in Eq. (2) are plentiful. Some of these are outlined in the following section. With fatty acid films, metal ions and complex metal ions containing something other than a divalent charge include Ag+, Fe3+, Ti(IV) from the transition metal series, U(III) from the actinide series, and M3+ from the lanthanide series (7). 

Catalytic Decomposition of Hydrogen Peroxide by Ferrous Ions Catalysis by Transition Metal Ions and Complexes in Liquid-Phase Oxidation of Hydrocarbons and Aldehydes by Dioxygen... 

The catalytic effect is achieved through the weak Lewis acid properties of the metal ion as the active site in the metal chelate compound. The residual Lewis acid activity of aquo metal ions and incompletely coordinated metal ions in complexes and chelates in aqueous solution is actually very weak compared to that of the hydrogen ion on the other hand, metal ions and complexes are available in solution at high pH values, where the concentration of hydrogen ions is so low that their catalytic effect cannot be significant. 

Many formation constants involve polycarboxylates Table 28 summarizes the data. Nagyp l and Fabian s report on the oxalic and malonic systems seems the most complete as hydrolysis of both metal ion and complexes has been included.584 A concentration distribution of the complexes in the malonic system is shown in Figure 25. The order of basicities is succinic > citraconic > itaconic > maleic > malonic acid and log /3U0 should follow the same order. However, from Table 28, the order of stabilities is citraconic > malonic > maleic > itaconic > succinic acid.608... 

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