Atomic Oxygen Cations

Ion Mobility Spectrometry-Mass Spectrometry Theory and Applications 

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According to investigations performed by Pakhomov and Kaidalova [204], the crystal structure of NF NbC consists of infinite chains made up of distorted octahedral ions (NbOF4 ) linked by oxygen atoms. Ammonium cations, NH/, occupy the spaces between the chains, as shown in Fig. 30. The packing of the structural units in the NH4NbOF4 crystal can be described as a CsCl type structure in which CF ions are replaced by Nb02F4 complexes and Cs" ions are replaced by ammonium ions. 

Figure 7. Crystal structures of (a) hollandite, (b) romanechite (psilomelane), and (c) todorokite. The structures arc shown as three-dimensional arrangements of the MnO() octahedra (the tunnel-tilling cations and water molecules, respectively, are not shown in these plots) and as projections along the short axis. Small, medium, and large circles represenl the manganese atoms, oxygen atoms, and the foreign cations or water molecules, respectively. Open circles, height z. = 0 fdled circles, height z = Vi.

Schroder, D., Schwarz, H., Hrusak, J. and Pyykkd, P. (1998) Cationic gold(l) complexes of xenon and of ligands containing the donor atoms oxygen, nitrogen, phosphorus, and sulfur. Inorganic Chemistry, 37, 624—632. 

The coordination of dioxane and subsequent oxidative addition to the catalytic species (step (a) in Scheme 20.16) probably proceeds after the oxygen atom coordinates to the rhodium (47), followed by abstraction of a hydrogen atom. The cationic species (48) then rearranges to a complex in which the dioxane is bound to the rhodium via the carbon atom (40) (Scheme 20.17) [60]. 

It has long been accepted that cyclic ethers with more than four-membered rings are, in contrast to epoxides, only cationically polymerizable due to the high basicities of their ether oxygen atoms. The cationic polymerization involves 0-... 

As calculations (Calle et al. 1992) show, the preferential approach of an alkaline cation to a 1,2-semidione is indeed in the middle of the two oxygen atoms. A cation-semid-... 

The results for the free energies of transfer of cations do not present as clear a picture. They suggest that solvents such as DMSO which contain a relatively basic oxygen atom solvate cations better than does water. To account for these solvation differences, cation-dipole interactions and solvent structure-making or -breaking effects could be invoked. Some cations (e.g., R3NH+) could also be stabilized in DMSO because of their ability to act as hydrogen bond donors. 

Aluminum cation % Phosphorus cation Oxygen atom Lanthanum cation Calcium cation... 

Clay minerals are hydrous layer silicates of colloidal dimensions, with most if not all of the individual platy particles in the colloidal range of c. 1 nm-1 pm (van Olphen, 1976 Van Damme et al., 1985). The term phyllosilicate (phyllo = leaf like) is applied to the broad group of hydrous silicates with layer structures. The essentia] components of the phyllosilicate structure are two-dimensional tetrahedra and octahedra of oxygen atoms (or ions). The coordinating atoms (or cations) in the centre of the tetrahedra are for the most part Si, but Al3 or Fe3+ may also be present. The coordinating cations in the octahedra are usually Al3, Mg2+, Fe3 or Fe2. Some clay structures (e.g. hectorite) can be synthesized in a reproducible and relatively homogeneous form. 

Fig. 7.9 HR-XPS of the U4f region of a reduced UO thin film (nominally close to fJOj after exposure (in Langmuir, L) to D O vapor at 300 K. The U4f j and Udf fines narrow due to the complete dissociation of water and the oxidation of U cations in oxidation states lower than four. An increase in the temperature resulted in further oxidation of the surface due to the migration of atomic oxygen from the bulk to the surface...

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