Nickel ions, reactions

In this reaction, the nickel ions of the nickel sulfate (NiSO ) are exchanged for the calcium ions of the calcium hydroxide [Ca(OH)2 ] molecule. Similarly, a resin with hydrogen ions available for exchange will exchange those ions for nickel ions from solution. The reaction can be written as follows ... 

R indicates the organic portion of the resin and SO3 is the immobile portion of the ion active group. Two resin sites are needed for nickel ions with a plus 2 valence (Ni ). Trivalent ferric ions would require three resin sites. As shown, the ion exchange reaction is reversible. The degree the reaction proceeds to the right will depend on the resins preference, or selectivity, for nickel ions compared with its preference for hydrogen ions. The selectivity of a resin for a given ion is measured by the selectivity coefficient. K. which in its simplest form for the reaction... 

Similar initial reactions occur on many metals such as iron and cobalt. This intermediate can now react further in one of two ways. Oxidation and protonation of the intermediate to Ni(II) leads to dissolved nickel ions (active corrosion) which are unable to passivate the metal ... 

Fig. 12.4 Corrosion diagram for a zinc diecasting in a nickel plating bath, pH 2-2. There are two possible cathodic reactions, hydrogen evolution (H) and nickel ion reduction (AO. The corrosion current is the sum of the partial cathode currents. Even with live entry the potential is still too high to suppress corrosion, though the rate is reduced to...

In 1965, Breslow and Chipman discovered that zinc or nickel ion complexes of (E)-2-pyridinecarbaldehyde oxime (5) are remarkably active catalyst for the hydrolysis of 8-acetoxyquinoline 5-sulfonate l2). Some years later, Sigman and Jorgensen showed that the zinc ion complex of N-(2-hydroxyethyl)ethylenediamine (3) is very active in the transesterification from p-nitrophenyl picolinate (7)13). In the latter case, noteworthy is a change of the reaction mode at the aminolysis in the absence of zinc ion to the alcoholysis in the presence of zinc ion. Thus, the zinc ion in the complex greatly enhances the nucleophilic activity of the hydroxy group of 3. In search for more powerful complexes for the release of p-nitrophenol from 7, we examined the activities of the metal ion complexes of ligand 2-72 14,15). 

The use of a nichrome stirrer or a catalytic amount of nickel ion is recommended 1 for such reactions to minimize the accumulation of diazonium xanthate however, the catalytic role of nickel ion has not been explored with other diazonium salts. 

E. Miscellaneous methods. Exchange reactions between the tetracyano-nickelate(II) ion [Ni(CN)4]2 (the potassium salt is readily prepared) and the element to be determined, whereby nickel ions are set free, have a limited application. Thus silver and gold, which themselves cannot be titrated complexometrically, can be determined in this way. 

This type of mechanism has been considered by Barnard et al. [83]. They postulate the initiation of the charging reaction at the Ni(OH)2 /current collector interface with the formation of a solid solution of Nij ions in Ni(OH)2. With further charging when a fixed nickel ion composition (Ni2+)v (Ni, +)1 A. is reached, phase separation occurs with the formation of two phases, one with the composition (Ni2+), r (Ni3+)v in contact with the cur-... 

Endothermic Reactions and the Determination of Bond Dissociation Energies for Organometallic Fragments. The reaction of atomic nickel ion with molecular hydrogen to yield NiH+is substantially endothermic. Reaction cross sections for this process, measured using the ion beam apparatus shown in Figure 1, are displayed in Figure 3 for reactions 1 and 2 with HD as the neutral. 

This reaction is called displacement deposition, because the nickel ions in solution simply displace the silicon at the surface. The substrate. Si, acts here as a reducing agent, as discussed in Chapter 9. Copper may be deposited on Si from HF acid solutions (69). In the presence of HF, Si is oxidized into [SiF5] . 

This enzyme [EC 1.18.99.1], also known as hydrogenly-ase, catalyzes the reaction of H2 with two oxidized ferre-doxin to produce two H+ and two reduced ferredoxin. This enzyme is an iron-sulfur protein and requires nickel ions. It can use molecular hydrogen to reduce a variety of substances. See also Hydrogen Dehydrogenase Cytochrome C3 Hydrogenase... 

Nickel tetracarbonyl may be prepared in the laboratory by the Hieber process, a disproportion reaction of several nickel compounds of organic thio acids, such as nickel(II) phenyldithiocarbamate, (CeHs— NH—C(=S)—S)2Ni, with carbon monoxide under controlled conditions. In such disproportionation reactions, the divalent nickel ion converts to a tetravalent nickel complex (Hieber. H. 1952. Z.anorg.Chem., 269, pp. 28). The overall reaction is ... 

The metal ion-water exchange process must be important in areas other than those of simple metal complex formation. For example, the discharge of nickel ion at a mercury cathode is probably controlled, not by diffusion, but by rearrangement of the water coordination shell. The estimated rates and heat of activation for this agree with the idea that this, in turn, is related to the water exchange process (66). Then too, the dimerization rate of metal hydroxy species may be controlled by water exchange. The reaction... 

A novel tridentate coordination mode for the carbonato-nickel(II) system was reported by Escuer and co-workers (61). The trinuclear compound [Ni2(p-C03)(dmpd)4(H20)][Ni(dmpd)2(H20)2](C104)4 H20 was obtained from the reaction of basic solutions of nickel(II) perchlorate and 2,2-dimethylpropane-1,3-diamine (dmpd) with atmospheric C02. The three nickel atoms show octahedral coordination with three different environments, №( 0 -0,0 )(dmpd)2, №( 0 -0 ) (dmpd)2(H20) and Ni(dmpd)2(H20)2. The carbonate anion acts as a bridge between two nickel ions whereas the [Ni(dmpd)2(H20)2]2 + subunit is linked by hydrogen bonds to the dinuclear group (Fig. 7). The dinuclear [Ni2(p-C03)(dmpd)4(H20)]2 + subunit shows a moderately weak antiferromagnetic coupling with a J value of —7.8 cm-1. 

As in the case of the reactions of the coordinated RS group, alkylation results in a weakening of the complexing ability of the ligand as evidenced by an expansion of the coordination number of the nickel ion. Similar reactions have been carried out with the complexes of palladium and platinum, and with all three metals and 2-pyridinaldoxime (POX). In the cases of palladium and platinum, one mole of coordinated ligand tends to be displaced by halide ions (Equation 48). 

An additional factor was found to influence the rate of reaction in the experiments involving tetrakis ( -mercaptoethylamine) trinickel (II) ion. The addition of nickel chloride retarded the process. Methanol was used as the solvent to demonstrate that the dependence was actually due to the presence of nickel ion and not an ionic strength effect. Magnesium chloride accelerates the rate slightly, while nickel ion greatly retards the rate of reaction. This effect was studied in greater detail, but solubility requirements necessitated the use of a water-methanol mixed solvent. A solution of 5.5M water in methanol was found to be satisfactory to obtain the necessary solubilities of complex and nickel chloride. 

The nickel ion dependence for the reaction between [Ni(NiL2)2]Cl2 and methyl iodide is such that a predissociation of the complex is suggested. The experimental rate law appropriate for this system is... 

The ion-exchange reaction of the synthetic zeolites NaX and NaY with cobalt, zinc and nickel ions is shown to be non-stoichiometric at low bivalent-ion occupancy, the hydrolytic sodium loss being about twice as large for NaX ( 5 ions/unit cell) as for NaY. The effect is more pronounced at high temperatures and disappears at high occupancies. Reversibility tests in NaX toward zinc and cobalt ions, as studied by a temperature-variation method, show the temperature history to be an important factor in the irreversibility characteristics. The low-temperature partial irreversibility, induced by a high-temperature treatment (45°C) is interpreted in terms of a temperature-dependent occupancy of the small-cage sites by divalent cations, which become irreversibly blocked at low temperature (5°C). 

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