Oxygen interaction exchange

The charge delocalization or the polarizability difference explains the selectivity behaviour in cases of high polarizability differences (complex versus aqueous metal ion) or in a homologous series of ions (either inorganic cations or ammonium cations). The smaller hydration status of all types of interlamellarly adsorbed cations is ascribed to the mutual stabilization by charge delocalization over the planar oxygens and exchangeable cations and is caused by the electrostatic interaction forces. 

The transannular interaction in the eight-membered (and also in nine-membered) ring amino ketones decreases the oxygen (170) exchange rate with water, as shown by 170 NMR, which also reveals an unusually shielded 170 chemical shift in such compounds (72HCA907). 

H-free surfaces. On hydrogen-free surfaces, the formation of terminal-CO species reveals the involvement of electron deficient (perturbed) Ni° metal sites. These sites can be generated consequently to (i) strong interactions of atomically dispersed (isolated) metal atoms with the support, and/or (ii) through-oxygen electron-exchange interactions with adjacent Ni impurity sites. Hence, the adsorption is weakened and the IR vCO frequency shifted upwards. As shown by Pearson [33], both incomplete reduction of metal ions and atomic dispersion of metal atoms are quite likely on surfaces of the electronically hard alumina. 

The study of the catalysis of isotopic exchange in molecular oxygen has begun rather lately and covers a limited number of catalysts and a rather narrow region of variation of conditions for carrying out reactions. Nevertheless, the results obtained enable us to hope that this type of reaction will be a useful method for the study of the mechanism of reactions of oxidation, and especially for the elucidation of nature of intermediate forms of oxygen interaction with solid catalysts. 

The selectivity to ethane is controlled by the oxygen partial pressure and thus the copper oxygen interaction. Experiments under steady state conditions at different temperatures shows that the deactivation of the catalyst corresponds to the formation of carbon and the destruction of the facettes on the catalyst surface. After a reaction time of about 6h the defined character or the facetted surface is exchanged by an undefined spongelike appearance. Both, the formation of carbon deposits and the change of the surface character of the facettes seems to be resposible for the deactivation of the copper catalyst during the reaction. 

Merkle R, Maier J, Bouwmeester FUM (2004) A linear free energy relationship for gas-solid interactions correlation between surface rate constant and diffusion coefficient of oxygen tracer exchange for electron-rich perovskites. Angew Chem Int Ed 43(38) 5069—5073... 

Figure 9.6 Visual representation of the platinum oxide growth mechanism, (a) Interaction of H2O molecules with the Pt electrode occurring in the 0.27 V < < 0.85 V range, (b) Discharge of 5 ML of H2O molecules and formation of 5 ML of chemisorbed oxygen (Ochem)- (c) Discharge of the second ML of H2O molecules the process is accompanied by the development of repulsive interactions between (Pt-Pt) -Ofi m surface species that stimulate an interfacial place exchange of Ochem and Pt surface atoms, (d) Quasi-3D surface PtO lattice, comprising Pt and moieties, that forms through the place-exchange process. (Reproduced with permission...

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