Other metal ions

Other Metal Ions.— Base hydrolysis of /rawj [Rh(en)aX2] ions leads to almost complete trans- cis isomerization when X = Cl or Br, and to ca. 50 % isomerization when X = I. Rates and activation parameters for the aquation and base hydrolysis reactions were considered previously (Table 22). An S Nlcb mechanism seems likely when X = Cl or Br, but an 5n11p mechanism cannot be ruled out when X = I. 

The activating effect of metal ions upon the base hydrolysis of co-ordinated organonitriles (RCN) in complex ions of the type [M(NH3)5(NCR)] + was considered in Volume 4 (p. 130) of this series. Further reports have appeared for M = Ru, Co, Rh, and Ir and for R = Me and Ru remains the most 

Base plays an important role in reducing Ru to Ru in a proposed solar energy storage system involving the [Ru(bipy)3] + ion.  

A review deals with the attack of hydroxide ion at the 2-position of co-ordinated bipyridyl-type ligands.  

In this section substitution reactions involving the formation (often anation) of inert metal complexes are discussed, with cations arranged in order of their increasing numbers of tZ-electrons. Metal ions with d , d, d or d electronic configurations are usually labile and most references to these systems will be found in Chapter 4. 

Other Metal Ions.—At 308.2 K, base hydrolysis of the [Rh(MeNH2)5Cl] + ion is ca. 29 times as fast as that of the [Rh(NHs)5Cl] + ion, and this is attributed partly to the increased acidity of the NH2 groups and partly to steric acceleration in the dissociative conjugate-base mechanism. For example, the pATa s of water molecules in [Rh(MeNH2)s(OH2)] + and iRh(NHs)5(0112)] + ions are 6.10 0.01 and 6.53 0.02 respectively at 295.2 K, and one can assume a similar trend for the NHg groups. This acidity difference can account for a factor of ca. 6 in the relative rates of base hydrolysis, and the remaining factor is attributed to steric effects. At 7=0.10 mol dm , the activation parameters for the base hydrolysis of [Rh(MeNH2)6Cl] + ion are AH = 108.6 kJ moH and AS =74.1 J K- mol-  

Presumably bimolecular attack by OH and CN- ions on the [Fe(bipy)3] + ion in mixed aqueous-organic solvents also occurs at the 2- or 9-positions of bipy, although 

Holba and O. Grancicova, Coll. Czech. Chem. Comm., 1977, 42, 819. 

Besides the alkali metals, the alkaline earth metals and aluminum, we also have the transition metals, among others. The charges that the cations of these metals have cannot be ascertained from their position in the periodic table. In addition, many of them form cations with several different charges. For example, iron can form cations with either a +3 charge or a +2 charge. The following are common metal ions  

Where there can be more than one possible charge for a given metal, Roman numerals are often used in the names in order to differentiate. For example, in this list, the names of the two iron ions are Iron(II) and Ironflll) and the names of the two copper ions are Copper(I) and Copper(II). The charges on monatomic ions are also their so-called oxidation number. More is presented on oxidation numbers in Chapter 13. 

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Thiosulfates. The ammonium, alkaU metal, and aLkaline-earth thiosulfates are soluble in water. Neutral or slightly alkaline solutions containing excess base or the corresponding sulfite are more stable than acid solutions. Thiosulfate solutions of other metal ions can be prepared, but their stabiUty depends on the presence of excess thiosulfate, the formation of complexes, and the prevention of insoluble sulfide precipitates. 

Three features of chelation chemistry are fundamental to most of the appHcations of the chelating agents. The first and probably the most extensively used feature is the control of free metal ion concentration by means of the binding—dissociation equiUbria. The second, often called the preparative feature, is that in which the special properties of the chelate itself provide the basis of the appHcation. The third feature comprises displacement reactions metal by other metal ions, chelant by chelant, and chelant by other ligands or ions. An appHcation may be termed defensive if an undesirable property in a process or product is mitigated, or aggressive if a new and beneficial property is induced. 

DispEcement. In many of the appHcations of chelating agents, the overall effect appears to be a displacement reaction, although the mechanism probably comprises dissociations and recombinations. The basis for many analytical titrations is the displacement of hydrogen ions by a metal, and the displacement of metal by hydrogen ions or other metal ions is a step in metal recovery processes. Some analytical pM indicators function by changing color as one chelant is displaced from its metal by another. 

In the treatment of poisoning by lead or other metal ions, higher concentrations of chelant can be safely obtained in humans by administering Na2CaEDTA rather than Na EDTA. The metal ion is bound by displacing small amounts of Ca " that the body can tolerate. Use of Na EDTA would result in calcium chelation and thus serious depletion of calcium in the body fluids (44). Removal of iron in Cooley s anemia is accompHshed by using chelants that are relatively specific for iron (45). 

The electrical conductivity also increases with increasing metal oxide content, due to the high mobility of the metal ions. For example several glass compositions have been used as solid electrolytes in galvanic cells in which other metal ions apart from the alkaline and alkaline earth ions have been incorporated. The electrochemical cell... 

Calcon carboxylic acid [3-hydroxy-4-(2-hydroxy-4-sulfo-l-napbtbylazo)napbtbalene-2-carboxylic acid] [3737-95-9] M 428.4, m 300°, X,max 560nm, pKj 1.2, pK2 3.8, PK3 9.26, PK4 13.14. Purified through its p-toluidinium salt. The dye was dissolved in warm 20% aq MeOH and treated with p-toluidine to ppte the salt after cooling. Finally recrystd from hot water. [Itoh and Ueno Analyst (London) 95 583 1970.] Patton and Reeder (Anal Chem 28 1026 1956) indicator and complexes with Ca in presence of Mg and other metal ions. 

Disodium succinate [150-90-3] M 162.1. Crystd twice from water (1.2mL/g) and dried at 125°. Freed from other metal ions by passage of a 0. IM soln through a column of Dowex resin A-1 (Na form). 

Lithium chloride [7447-41-8] M 42.4, m 600 , 723 . Crysld from water (ImL/g) or MeOH and dried for several hours at 130 . Other metal ions can be removed by preliminary crystallisation from hot aqueous 0.0 IM disodium EDTA. Has also been crystallised from cone HCl, fused in an atmosphere of dry HCl gas, cooled under dry N2 and pulverised in a dry-box. Kolthoff and Bruckenstein [J Am Chem Soc 74 2529 1952] ppted with ammonium carbonate, washed with Li2C03 five times by decantation and finally with suction, then dissolved in HCl. The LiCl solution was evaporated slowly with continuous stirring in a large evaporating dish, the dry powder being stored (while still hot) in a desiccator over CaCl2. 

Note The copper in the reagent may be replaced by other metal ions. Table 1 [3] lists the colors obtainable with some cations. 

The complexation of 6, ciprofloxacin, and lomefloxacin with metals ions were studied in aqueous solution (pD 2.5 37 °C) by and NMR spectroscopy (99MI18). Titration experiments have revealed that the binding ability of 6 towards Al " " ion is much stronger than that of ciprofloxacin and lomefloxacin. Other metal ions (Ca " " and Mg " ") formed much weaker complexes. 

Even small traces of certain corrosion stimulants, notably soluble chlorides and sulphates, can maintain a continuing corrosion process under a paint film because the salts accelerate the initial dissolution of ferrous iron (and other metal ions) but are not immobilised in the hydrated oxide corrosion products. Filiform corrosion is the most spectacular example of this phenomenon, but progressive spread, preceded by blistering, is also observed from scratches or other breaks in a coating, for example during salt spray tests. 

Chemical interaction with other metal ions shifts Equilibrium (52) to the right (alkaline side) and yields certain types of compounds according to the acidity of the added metal. 

Other fluorinated derivatives of acetylacetone are trifluoroacetylacetone (CF3COCH2COCH3) and hexafluoroacetylacetone (CF3COCH2COCF3), which form stable volatile chelates with aluminium, beryllium, chromium(III) and a number of other metal ions. These reagents have consequently been used for the solvent extraction of such metal ions, with subsequent separation and analysis by gas chromatography [see Section 9.2(2)]. 

Copper(II) compounds. Many other metallic ions which are capable of undergoing oxidation by potassium iodate can also be determined. Thus, for example, copper(II) compounds can be analysed by precipitation of copper)I) thiocyanate which is titrated with potassium iodate ... 

In the above route, zinc(II) can be replaced by other metal ions such as copper(II) and nickel(II). The pinacol approach to isobacteriochlorins has also been successfully applied to the synthesis of heme dj. 20a b... 

In presence of acids or other metal ions the five-unit macrocyclc of superphthalocyanines can be contracted to produce metal-free phlhalocyanine or metal phthalocyanines, respectively. This reaction might be more of scientific interest than of synthetic value. Nevertheless, one example is shown below. 

Related programs, such as phosphate-chelant and phosphate-polymer, are simply modifications of the basic phosphate-cycle, and they still rely on the precipitation of calcium (or other metal ions) as dispersible phosphate sludge. 

Disproportionation of Pu(IV). There are several needs associated witn the occurrence, detection, and mitigation of the disproportionation of Pu(IV) in applied plutonium recovery/ purification procedures. First, there is a great need for much more detailed information concerning the effect of typical process conditions [e.g., temperature, concentration of plutonium, hydrogen ion, nitrate ion, nitrite ion, fluoride ion, other metal ions (e.g., A13+, Fe3+, etc.), etc.] on the occurrence and extent of the reaction ... 

Unlike 2-thiazolidinethione and its simpler derivatives, the 3 - alkyl - 5 - hydroxy - 5 - (1,2,3,4 - tetrahydroxy -n- butyl) - 2 - thiazoli-dine thiones [which are specific, photometric reagents for Cu(ID] undergo rearrangement in the presence of Cu(II) ions, to form complexes of dithiocarbamate. The analytical specificity is explained by the inability of most other metal ions to effect this rearrangement (419). 

In 1968, reports from Sweden, subsequently confirmed in other industrial countries, noted that shallow lakes with low concentrations of divalent cations were becoming more acidic with consequent decreases in aquatic plants and animals. In severely affected lakes and ponds, only acidophilic algae survived. Increased acidity and the runoff of solubilized aluminum and other metal ions from surrounding watersheds are now known to be primarily responsible for formation of these almost sterile bodies of water. 

Kustin K, McLeod GC, Gilbert TR, Briggs LR (1983) Vanadium and other Metal Ions in the Physiological Ecology of Marine Organisms 53 137-158... 

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