Complexation by metals

The general, selective and specific formation of complexes by metallic cations. G. Schwarzenbaeh, Adv. Inorg. Chem. Radiochem., 1961, 3, 257-285 (70). 

The equation for the formation of a complex by metal A and ligand B is written as... 

The photophysical properties (extinction coefficient, shifts in absorption and emission spectra, quantum yield, and lifetime) of a variety of probes are modified by pH changes, complexation by metal ions, or redox reactions. The resulting changes in photophysical parameters can be used to determine concentration of H+ and metal cations with suitably designed fluorophores. Most of these resulting sensors involve an equilibrium between the analyte, A, and the free probe (unprotonated or noncom-plexed by metal ion), Pf. If the stoichiometry of this reaction is 1 1, the reaction may be represented by... 

The General, Selective, and Specific Formation of Complexes by Metallic Cations... 

Reductive lithiation of allyl phenyl sulfides.1 This reagent is particularly useful for preparation of allyllithium reagents at temperatures at which the anions are stable. Moreover, regioselectivity in reactions can be achieved by conversion to allyltitanium(IV) complexes by metal exchange with Ti(0-/-Pr)4. Thus the un-symmetrical anion formed from the allyl sulfide 1 with LDMAN reacts with cro-tonaldehyde to give a mixture of 1,2- and 1,4-adducts. The 1,2-adduct 2 can be obtained in high yield as two diastereomers (9 1) by use of the allyltitanium complex (equation I). 

Complexation by metal oxides and clays. The adsorption processes of metals on silica, alumina, hydrated ferric oxide and a range of other minerals are well documented for laboratory studies performed with synthetic materials (Buffle, 1988 Dzombak and Morel, 1990 Stumm, 1992). The approaches described for major sites are applicable in this case. Nevertheless, the relevance of these data to natural water... 

Catalytic constants for iodination of 2-acetylpyridine (HS) complexed by metal ions"- ... 

This square planar zinc complex is an excellent intermediate for the preparation of other BZO4 [16] octaene N4 complexes by metal exchange, and its use alleviates the problem of separating the desired complex from other reaction side products when o-aminobenzaldehyde is condensed in the presence of the appropriate metal ion. Complexes of nickel, cobalt, iron, and palladium have been prepared from this zinc compound. 

Spectroscopic Characterization of Inorganic and Organometallic Complexes by Metal and High-Pressure NMR... 

It is difficult to estimate what the rate of the metal ion catalyzed oxidative deamination reaction of amino acids would be in natural waters. Hamilton and Revesz (30) found that the rate of oxidation of alanine in the presence of pyridoxal and manganese ions was inhibited by EDTA. Since metal ions in natural waters can be complexed by a variety of organic and inorganic compounds, their effectiveness in catalyzing the oxidative deamination of amino acids may be reduced. Also, the fraction of dissolved amino acids which would be complexed by metal ions at the pH and metal ion and amino acid concentrations found in natural waters must be considered. At neutral pH, where the amino group of the amino acid is protonated, the fraction of the amino acid that would be in the form of the metal ion complex depends upon the equilibrium constant for the formation of the complex and the pK of the amino proton of the amino acid. The reactions for the formation of the Cu2+-alanine complexes can be written as... 

Reactivity of Various Tertiary Diamines in the Preparation of Tertiary Diamine Organolithium Complexes by Metalation. Previous work has shown that the reactivity and the rate of metalation for Reaction 2 of the tertiary diamine organolithium complexes is a function of the tertiary diamine in the complex (1,9). In the specific case of the metala-... 

S.8.2.4.6. tt-Allyl Metal Complexes by Metal-Atom and Related Reactions. 

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