O-H activation

Although of animal origin, the lectin from the eel Anguilla anguilla) is an interesting and useful reagent with anti-O(H) activity [225]. It is specific for a-L-fucosyl groups. 

The aqueous-phase dehydrogenation mechanism [24] was found to follow similar paths and relative ordering of the C-H and O-H activation steps as that found for the vapor-phase case [15,16,17], despite the fundamental differences that result from the heterolytic versus homolytic activation. The optimized structures [24,25] and reaction energies [24,25] (including vapor-phase reaction energies [15,16,17] in parentheses) for the aqueous phase methanol decomposition over Pt(l 11) are presented in Figure 19.5. 

In general, both the vapor phase as well as the aqueous phase reaction pathways indicate that C H bond activation is preferred over O H activation for most of the surface intermediates. The crossover to O H activation appears to require the activation of some of the C-H bonds first. This case study demonstrates the strong influence of the aqueous phase on determining both the fundamental pathway and energetics of electrocatalytic processes. 

Figure 6.4. The hemolytic activation of water over Pt(lll). On the left water adsorbed reactant state. In the center the transition state for O-H activation. On the right the surface hydroxyl and hydride products P " .

Keywords Alcohols Amides Amines Carbon dioxide Catalysis Dehydrogenative coupling Esters Hydrogen Imines Iridium Metal-ligand cooperation O-H activation Pincer complexes PNN PNP Ruthenium... 

---