Reactions with cations

To simplify the following discussion EDTA is assigned the formula H4Y the disodium salt is therefore Na2H2Y and affords the complex-forming ion H2 Y2 in aqueous solution it reacts with all metals in a 1 1 ratio. The reactions with cations, e.g. M2+, may be written as ... 

Fig. 6 Changes in concentration of anion [2 ] determined from the visible spectrum for the reaction with cation [28 ] in various solvents at 25°C. Initial concentration ...

Hydroxylating system chemical reaction with cation radicals produced by peroxidases... 

The electrochemical reduction of W-acyliminium ion pool 2 gave rise to the formation of the corresponding homo-coupling product 13 (Scheme 8).23 Presumably, a radical intermediate 14 was generated by one electron reduction of 2 and homo-coupling of the radical led to the formation of the dimer 13. However, a mechanism involving two-electron reduction to give anion 15 followed by the reaction with cation 2 cannot be ruled out. 

The inertness of isobutene to radicals and anions, and its ready reaction with cations have produced a conviction that the activity of every catalyst which will polymerise... 

Anilinocyclophosphazene, 21 72 Anionic carbonyl cluster, reaction with cationic mononuclear complexes, 30 155-158... 

Strong acid cation exchange resins manufactured by the sulphonation of polystyrene or poly divinyl benzenes undergo the following reaction with cations ... 

IV. Competitive Reactions with Cationic Phosphenium Complex Formation. . 120... 

COMPETITIVE REACTIONS WITH CATIONIC PHOSPHENIUM COMPLEX FORMATION... 

Clark and his co-workers have shown that water will provide a convenient source of the hydro ligand in reactions with cationic platinum(II) complexes (Eq. 40). Reaction occurs when L is triethylphosphine or triphenylphosphine 93, 81), when X is a halogen, and also when L is an alkylarsine 80). The mechanism has been studied and is considered to proceed via an intermediate carboxylate 95, 96). 

Compared to manganese, little work has been carried out on analogous alkyl complexes of rhenium, although that which has may be divided into the same categories, namely, (1) reaction with transition metal hydrides, for example [CpW(H)(CO>3] (2) reaction with Lewis acids, for example, AlCUEt (3) orthometallation reactions (4) reaction with cationic species, for example, (5) reaction with anionic nucleophiles, for example, BF4" (6) reaction with neutral nucleophiles, for example, PPh3-... 

Beck and co-workers (84,8.5) utilized the anionic carbonylmetallates [M(C0)5] (M = Mn, Re) and [WCp(CO),] in nucleophilic addition reactions with cationic hexadienyl, cyclohexadienyl, cycloheptadienyl, and cyclooctadienyl complexes of iron and ruthenium to give heterobimetal lie complexes with rj iV-hydrocarbon bridges. The reaction of [Fe(i7 -... 

Figure 8.26 Schematic diagram of a cation-exchange resin framework with fixed exchange sites prior to and following an exchange reaction (a) initial state prior to exchange reaction with cation B (b) equilibrium state after exchange reaction with cation B. ...

Tetradentate or hexadentate ligands are more satisfactory as titrants than ligands with a lesser number of donor groups because their reactions with cations are more complete and because they tend to form I I complexes. 

C.D. Ritchie and RO.L. Virtanen, Cation-Anion Combination Reactions. IX. A Remarkable Correlation of Nucleophilic Reactions with Cations, J. Am. Chem. Soc., 1972,94,4966 C.D. Ritchie, Cation-Anion Combination Reactions. CC. A Review, Can. J. Chem., 1986,64,2239. 

A related reachon involves tandem reactions, with cationic Pd-aUyl complexes... 

Some of these vinyl monomers can delocalize the positive charge, and this also facilitates reactions with cations, e.g., in the polymerization of vinyl ethers ... 

The permanent negatively charged surface sites at the siloxane layer (XO) are accessible to ion-exchange reactions with cations, such as Na+, K +, Ca2 +, and Al3+ (inset in Fig. 14) (Schindler et al., 1987). 

Aromatic cation radicals are often very stable in sulfuric acid solution. The major reason for this is that the solution is only weakly nucleophilic. The free water content is very small and the nucleo-philicities of sulfate and bisulfate ions are too low for reaction with cation radicals. Cation radicals which have removable protons participate in acid-base equilibria with the corresponding neutral radicals and would be expected to be predominantly in the acid form in sulfuric acid. For example, the phenothiazine cation radical becomes the neutral phenothiazinyl radical on deprotonation and the neutral radical dimerizes to biphenothiazines (11) (Tsujino, 1968 Shine et al., 1972 Hanson and Norman, 1973). 

To our knowledge no reaction of iodide ion as a nucleophile with a cation radical is known. Iodide ion reduces cation radicals very well and is frequently used for the iodimetric assay of cation-radical salts. Since the reduction is reversible and some compounds can be oxidized to the cation radical stage by iodine, an excess of iodide is used. Some cation radicals are also reduced by other halide ions for example, that of 9,10-diphcnylanthracene is reduced by bromide ion (Sioda, 1968), that of perylene by bromide and chloride ions (Ristagno and Shine, 1971b), and thianthrene radical cation to some extent by chloride ion (Murata and Shine, 1969). These reductions, particularly those by iodide ion, reflect again the competition between nucleophilicity and oxidizability of a nucleophile in reactions with cation radicals. 

For this reason, we consider it hardly possible to cite all of the publications. Let us focus only on the following examples. Hydroxamic acids have already been for a long time subject of the classical analytical chemistry. In [71], the possibility of using these compounds in flotation of rare-earth minerals is shown. It has been concluded that on a mineral surface cerium chelates are formed. Besides, chemisorption is accompanied by a physical multilayer adsorption of hydroxamic acid derivatives formed by reaction with cations in the water phase. A number of chelate-forming compounds including hydroxamic acids has been tested in flotation of niobium ores [72]. The best results are obtained when using alkyl phosphonic acids. Chemisorption mechanism and the structure of the surface compounds are established by spectroscopic methods. 

Nucleophilic Addition Reactions with Cationic Iron jt-Alkyne and Related Complexes"... 

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