Reactivity, elementary ideas

This book starts from the most elementary ideas of molecular orbital theory, and it leads the reader progressively towards an understanding of the electronic structure, of the molecular geometry and, in some cases, the reactivity of transition metal complexes. 

The mechanisms by which an inhibitor adds to an oxidized hydrocarbon exerts its influence may differ depending on the reaction conditions. If the rate constants of the elementary reactions of RH, InH, R02 , In, ROOH, and 02 are known, the kinetics of the inhibited oxidation of RH can mathematically be described for any conditions. However, such an approach fails to answer questions how the mechanism of inhibited oxidation is related to the structure and reactivity of InH, RH, and R02 or what inhibitor appears the most efficient under the given conditions, and so on. At the same time, these questions can easily be clarified in terms of a topological approach whose basic ideas are the following [43-45,70-72] ... 

Langmuirian view, the active catalytic surface is comprised of a uniform distribution of static sites that do not interact with one another. This is sharply contrasted by the Taylor view, which proposes vacancies and topologically unique surface atom configurations as the centers of reactivity. The Langmuirian idea of a catalytically reactive surface leads to the ensemble effect that ascribes the changes in the selectivity for an alloy surface to the dilution of multi-atom surface ensembles in the alloy induced by mixing inert components into the active surface. In this view, the selectivity of a particular reaction depends predominantly on the number of reactive surface atoms that participate in elementary reaction events. 

In this chapter we extend our treatment of mechanisms for metal-catalyzed reactions in the vapor phase to heterogeneous catalytic reactions carried out in aqueous media and electrocatalytic reactions. More specifically, we discuss what is known about the wa-ter/metal interface, its reactivity, and the influence of the aqueous phase on elementary surface processes including adsorption, reaction, diffusion and desorption and sofution-phase kinetic processes. We advance these ideas into the discussion of the mechanisms... 

---