Oxidation cationic

The ultraviolet spectra of the neutral molecule and the cation in water show very similar behavior to quinazoline and its cation (see Fig. 4). By analogy, the quinazoline 3-oxide cation must be co-... 

To avoid this phase change, zirconia is stabilized in the cubic phase by the addition of a small amount of a divalent or trivalent oxide of cubic symmetry, such as MgO, CaO, or Y2O3. The additive oxide cation enters the crystal lattice and increases the ionic character of the metal-oxygen bonds. The cubic phase is not thermodynamically stable below approximately 1400°C for MgO additions, 1140°C for CaO additions, and below 750°C for Y2O3 additions. However, the diffusion rates for the cations are so low at Xhtstsubsolidus temperatures that the cubic phase can easily be quenched and retained as a metastable phase. Zirconia is commercially applied by thermal spray. It is also readily produced by CVD, mostly on an experimental basis. Its characteristics and properties are summarized in Table 11.8. 

SPECTROSCOPY OF THE POTENTIAL ENERGY SURFACES FOR C-H AND C-O BOND ACTIVATION BY TRANSITION METAL AND METAL OXIDE CATIONS... 

Spectroscopy of the PES for reactions of transition metal (M ) and metal oxide cations (MO ) is particularly interesting due to their rich and complex chemistry. Transition metal M+ can activate C—H bonds in hydrocarbons, including methane, and activate C—C bonds in alkanes [18-20] MO are excellent (and often selective) oxidants, capable of converting methane to methanol [21] and benzene to phenol [22-24]. Transition metal cations tend to be more reactive than the neutrals for two general reasons. First, most neutral transition metal atoms have a ground electronic state, and this... 

Methane-to-methanol conversion by gas-phase transition metal oxide cations has been extensively studied by experiment and theory see reviews by Schroder, Schwarz, and co-workers [18, 23, 134, 135] and by Metz [25, 136]. We have used photofragment spectroscopy to study the electronic spectroscopy of FeO" " [47, 137], NiO [25], and PtO [68], as well as the electronic and vibrational spectroscopy of intermediates of the FeO - - CH4 reaction. [45, 136] We have also used photoionization of FeO to characterize low lying, low spin electronic states of FeO [39]. Our results on the iron-containing molecules are presented in this section. 

Spectroscopy of the Potential Energy Surfaces for C-H AND C-O Bond Activation by Transition Metal and Metal Oxide Cations 331 By R. B. Metz... 

Fig. 2 Calculated low energy conformation of the protonated dithiane oxide cation (R=H) in zeohte Y (Si/Al = 1). The bottom view shows a view through the twelve ring containing e deprotonated framework oxygen, the top view is perpendicular to this. For clarity the zeolite framework is shown using a stick model and the adsorbed molecule is drawn in space filled form represented by tlie Van der Waals radii for the atoms being in the order S>0>C>H.

Fig. 3 Calculated low energy conformation of the protonated dithiane oxide cation (R=phenyl) in zeolite Y (Si/Al = 1). The views and presentational details are as for figure 2.

Schroder, D., Schwarz, H., 1995, C-H and C-C Bond Activation by Bare Transition-Metal Oxide Cations in the Gas Phase , Angew. Chem. Int. Ed. Engl., 34, 1973. 

Current state-of-the-art technology for the production of MIBK involves one-step liquid phase processes in trickle bed reactors at 100-160°C and 1 to 10 MPa utilizing various multifunctional catalysts including Pd, Pt, Ni or Cu supported on, metal oxides, cation exchange resins, modified ZSM5 and other zeolites with lull energy integration (2,3,4). However, the MIBK... 

The pollutant or solute cycle — that may encompass the processes of advection, diffusion, volatilization, adsorption and desorption, chemical degradation or decay, hydrolysis, photolysis, oxidation, cation or anion exchange, complexation, chemical equilibria, nutrient cycles, and others (see section 3.0). 

Radon reacts spontaneously at room temperature with many solid compounds that contain oxidizing cations, such as BrF2, IF, 02, and N2F (Stein, 1972, 1973, 1974 Stein and Hohorst, 1982). Xenon also reacts with a few compounds of this type which have very high oxidation potentials (Stein, 1973, 1974). The xenon products have been analyzed by Raman and mass spectrometric methods and shown to... 

XRD patterns of the prepared samples V-Mo-Zeolite are similar to that of zeolites which suggests that the metal species (i.e. oxide, cations,...) are well dispersed through the zeolites structure and the absence of bulk phases in the XRD patterns implies that for these samples the molybdenum and vanadium oxides are present in either a nanocrystalline state or as a small crystallites which measured less than 4 nm in diameter. Furthermore, XRD and FTIR (1500-400 cm 1) showed no significant damage of the zeolite host structure after exchange and thermal treatment except for the sample V2MoMor. 

Generally, the ionization of Pcs not only increases their solubility but also alters their %-% stacking structures, especially in the presence of large balanced ions. The Pc skeleton in these compounds can be integrally or partly oxidized cationic H2Pc+, or anionic Pc(l-) and Pc(l-). According to the charge type of Pc moiety, ionic Pcs can be classified as cationic Pcs and anionic Pcs. The cationic and anionic Pcs published recently are listed in Tables 7 and 8, respectively. 

A major concern of this review is the tailoring of the redox behaviour of organic compounds, i.e. the optimization of such systems for electron storage and electron hopping. While the emphasis is on reduction and thus on anion formation, it has been shown on many occasions that oxidative cation formation leads to analogous conclusions (Meerholz and Heinze, 1990 Lewis and Singer, 1965). The structure of this text is thus obvious. 

The lanthanide oxide cations [LnO]+ and the bare lanthanide ions Ln+ react differently with butadiene (162). Some bare Ln+ ions (La, Ce, Pr, Gd) activate butadiene but their oxide cations are inert toward butadiene. The lanthanides with weak M-O bonds, EuO and YbO, react by oxygen transfer to the butadiene. The oxide cations of Dy, Ho, Er, and Tm activate butadiene, whereas the bare metals of these lanthanides are unreactive with butadiene. The [HoO]+ ion has been studied in detail and is able to polymerize butadiene the mechanism of this reaction has been discussed. 

Oxide Cation Surface complex Stability constant Reference... 

Table 3 Physical constants of the radicals TEMPO (tetramethylpiperidinyl-iST-oxyl), 1,3,5-triphenylverdazyl (10), and their complexes with the oxidized cation salts...

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