Type of cation

Values of A0 are generally higher for trivalent cations than for corresponding divalent ions. This is demonstrated by the data summarized in table 2.5 for divalent and trivalent transition metal ions in simple oxide structures and in hydrated environments. For example, A0 values for Fe2+ and Fe3+ ions in aqueous solution are 10,400 cm-1 and 13,700 cm-1, respectively. 

There is a general sequence of Ac values which increase in the order 

This sequence is particularly well characterized for fluoride complexes of high-spin cations of the first-series transition elements (Allen and Warren, 1971). Moreover, between successive transition metal series, values of Ac increase by about thirty to fifty per cent. For example, in hydrated cations of the first and second transition series, Ac for [CftHjO) 3 and [Mo(H20)6]3+ are 17,400 cm-1 and 26,110 cm-1, respectively. 

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The actinide elements exhibit uniformity in ionic types. In acidic aqueous solution, there are four types of cations, and these and their colors are hsted in Table 5 (12—14,17). The open spaces indicate that the corresponding oxidation states do not exist in aqueous solution. The wide variety of colors exhibited by actinide ions is characteristic of transition series of elements. In general, protactinium(V) polymerizes and precipitates readily in aqueous solution and it seems unlikely that ionic forms ate present in such solutions. 

SFA has been traditionally used to measure the forces between modified mica surfaces. Before the JKR theory was developed, Israelachvili and Tabor [57] measured the force versus distance (F vs. d) profile and pull-off force (Pf) between steric acid monolayers assembled on mica surfaces. The authors calculated the surface energy of these monolayers from the Hamaker constant determined from the F versus d data. In a later paper on the measurement of forces between surfaces immersed in a variety of electrolytic solutions, Israelachvili [93] reported that the interfacial energies in aqueous electrolytes varies over a wide range (0.01-10 mJ/m-). In this work Israelachvili found that the adhesion energies depended on pH, type of cation, and the crystallographic orientation of mica. 

When is approximately the same size as Ti (i.e. M = Mg, Mn, Fe, Co, Ni) the stmcture is that of ilmenite, FeTi03, which consists of hep oxygens with one-third of the octahedral interstices occupied by and another third by Ti This is essentially the same structure as corundum (AI2O3, p. 243) except that in that case there is only one type of cation which occupies two-thirds of the octahedral sites. 

The extensive possibilities of the practical application of synthesis, and the study of the properties of ion-ex-change resins have aroused widespread interest in chemistry. This chapter discusses some theoretical problems with cationic resins as catalysts in hydrolysis reactions. New types of cationic resins have been examined and some important generalizations on ion-exchange reactions have been formulated. 

Table 20.2 lists the formulas of the oxides formed when the more common transition metals react with oxygen. With one exception (Cu20), the transition metal is present as a +2 and/or a +3 ion. In Co304 and in other oxides of general formula M304, there are two different types of cations +2 and +3. To be specific, there are twice as many +3 as +2 cations we might show the composition of Co304 as... 

The name of a monatomic cation is the name of the element plus the word ion for elements that can form more than one type of cation, the oxidation number, a Roman numeral indicating the charge, is included. 

The first equation takes charge balance into account, the requirement that the solution must be electrically neutral overall. That is, the concentration of cations must equal that of anions. Because there is only one type of cation, H30+, the concentration of H.O+ ions must equal the sum of the concentrations of the two types of anions, Cl and Ol I. The charge-balance relation [H3CC] = [Cl ] + [OH ] then tells us that... 

Polysulfides have been prepared with many different types of cations, both monoatomic Hke alkah metal ions and polyatomic Hke ammonium or substituted ammonium or phosphonium ions. In this chapter only those salts will be discussed in detail which contain univalent main-group cations although a large number of transition metal polysulfido complexes have been prepared [7-9]. 

John D. Corbett once said There are many wonders still to be discovered [4]. This certainly holds generally for all the different areas and niches of early transition cluster chemistry and especially for the mixed-hahde systems. The results reported above so far cover a very Hmited selection of only chloride/iodide systems and basically boron as the interstitial. Because of the very sensitive dependence of the stable stracture built in the soHd-state reaction type on parameters like optimal bonding electron counts, number of cations present, size and type of cations (bonding requirements for the cations), metal/halide ratio, and type of halide, a much larger mixed-hahde cluster chemistry can be expected. Further developments, also in mixed-hahde systems, can be expected by using solution chemistry of molecular clusters, excised from solid-state precursors. 

The effects of substituents upon the ferroin reduction have also been recorded (Table 25) . A marked correlation between E and log A is found, indicating a single type of cation-anion interaction. 

In this system two types of cation are exchanged between the phases. The elec-... 

For a few membrane electrodes the ion selectivity is limited, e.g., the Metrohm EA301-Me2+ electrode shows the same sensitivity for various divalent cations in fact, even non-selectivity may be accepted, e.g., where only one type of cation is present as in aqueous hydrofluoric acid where the pH can be determined with a cation-exchange resin electrode40. 

Some remarks can be made about the evolutions in the presence of Ca2+, although it is difficult to think that some brine could contain only this type of cations without monovalent cations. Before any aging, a copolymer of 17% of acrylate content begins to demix for CaCl2 > 2.5 10 2 M/l and this limit is lower for higher... 

Ans. Two—one type of cation and one type of anion. (Some alums have three types of ions.)... 

Citterio D, Sasaki S, Suzuki K (2001) A new type of cation responsive chromoionophore with spectral sensitivity in the near-infrared spectral range. Chem Lett 30 552-553... 

Although the work discussed thus far has covered primarily neutral organic radicals, there are many types of cation and anion radicals that are stabilized on the surface. Some of these ion radicals are formed through photochemical processes however, many others are spontaneously generated on a surface. The type of radical ion that is formed depends on the oxidizing or reducing character of particular sites on the surface, as well as on the ionization potential and the electronegativity of the adsorbed molecule. 

Values of F ed for many types of cationic oxidants (particularly those based on transition metals72) have been tabulated,73 and some of the more common... 

Complex cyanides are compounds in which the cyanide anion is incorporated into a complex or complexes. These compounds are different in chemical and toxicologic properties from simple cyanides. In solution, the stability of the cyanide complex varies with the type of cation and the complex that it forms. Some of these are dissociable in weak acids to give free cyanide and a cation, while other complexes require much stronger acidic conditions for dissociation. The least-stable complex metallocyanides include Zn(CN)42 , Cd(CN)3 , and Cd(CN)42 moderately stable complexes include Cu(CN)2, Cu(CN)32, Ni(CN)42, and Ag(CN)2 and the most stable complexes include Fe(CN)64, and Co(CN)6. The toxicity of complex cyanides is usually related to their ability to release cyanide ions in solution, which then enter into an equilibrium with HCN relatively small fluctuations in pH significantly affect their biocidal properties. 

Attempts to directly observe the cations A and A by low-temperature NMR, developed in the studies 274 and 478, made it possible to detect both types of cations (293) (Scheme 3.219). 

A The name of each of these ionic compounds is the name of the cation followed by that of the anion. Each anion name is a modified (with the ending ide ) version of the name of the element. Each cation name is the name of the metal, with the oxidation state appended in Roman numerals in parentheses if there is more than one type of cation for that metal. 

Solid electrolytes are frequently used in studies of solid compounds and solid solutions. The establishment of cell equilibrium ideally requires that the electrolyte is a pure ionic conductor of only one particular type of cation or anion. If such an ideal electrolyte is available, the activity of that species can be determined and the Gibbs energy of formation of a compound may, if an appropriate cell is constructed, be derived. A simple example is a cell for the determination of the Gibbs energy of formation of NiO ... 

Alkoxycarbenium ions are important reactive intermediates in modem organic synthesis.28 It should be noted that other names such as oxonium ions, oxocarbenium ions, and carboxonium ions have also been used for carbocations stabilized by an adjacent oxygen atom and that we often draw structures having a carbon-oxygen double bond for this type of cations.2 Alkoxycarbenium ions are often generated from the corresponding acetals by treatment with Lewis acids in the presence of carbon nucleophiles. This type of reaction serves as efficient methods for carbon-carbon bond formation. 

The different types of cations, anions, and other species likely to be involved in the cationoid polymerisations of alkenes are discussed, with special reference to their relative abundance under different conditions. 

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