Multiply-charged cations

We have been able, however, on occasions to use a very simple model to help understand specific plant problems where river water analyses were available and on one occasion to show that at different times the boiler water had (as corrosion evidence suggested) alternated between acidic and alkaline conditions. The model assumes that by 350 C any normally dissociated multi-charged ions will be sufficiently unstable that they will undergo whatever appropriate hydrolysis reactions can reduce their charge to unity. Whether the water goes acid or alkaline then simply depends on whether the total (equivalent) concentration of multiply charged cations exceeds or is smaller than the concentration of multiply charged anions. 

Figure 7.6.6. Phosphorus containing dendrimers forming multiply charged cations.

Historically, water hardness was defined in terms of the capacity of cations in the water to replace the sodium or potassium ions in soaps and to form sparingly soluble products that cause scum in the sink or bathtub. Most multiply charged cations share this undesirable property. In natural waters, however, the concentrations of calcium and magnesium ions generally far exceed those of any other metal ion. Consequently, hardness is now expressed in terms of the concentration of calcium carbonate that is equivalent to the total concentration of all the multivalent cations in the sample. 

EDD is a promising new FTICR technique, and is the negative ion complement to ECD. Both these electron-mediated techniques involve a radical ion intermediate, produced by either electron attachment to multiply charged cations (ECD) (Equations (48) and (49)) or electron removal from multiply charged anions (EDD) (Equation (50)). 

Stephenson, J.L. McLuckey, S.A. Adaptation of the Paul Trap for study of the reaction of multiply charged cations with singly charged anions. Int. J. Mass Spectrom. Ion Processes 1997,162, 89-106. 

Multiply charged cations are formed by attachment of several protons. This process usually occurs for biomolecules in the ESI mode of ionization. The corresponding ions will appear at [M - - nH]"+/n, where M is the molecular mass of the biomolecule, n the number of protons it can accept, and H the mass of a proton. Thus, M and miq can have two distinct values. These values are identical only for singly charged ions. This distinction is clearly explicable in Example 1.2. 

Rearrangements in multiply charged cationic species and Lewis acid-catalysed ( ) enantioselective isomerizations to form one or more stereogenic centres, with a special focus on allylic rearrangements, have been reported. (g)... 

Fragmentation following gas-phase electron capture by positive ions is termed dissociative recombinatioa BCD is based on the dissociative recombination of multiply-charged cations (M+nH)"+ with low-eneigy electrons (<1 eV), generating charge-reduced radical species (M+nH)( > and product ions [51, 52]. 

A means to deposit energy in multiply charged cation complexes is by the exothermic addition of an electron. The technique of electron transfer dissociation (ETD) employs as an electron donor the polycyclic aromatic hydrocarbon fluoranthene anion, CieHio , the electron binding energy for which is only 0.6 eV. An important characteristic of ETD when applied to metal ion complexes is that the process results in both charge reduction and chemi-... 

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