Polyoxoanions model

Using the well-defined system of polyoxoanion/Bu4N -stabilized iridium nanoparticles [9, 29] as a model for the studies, Finke and coworkers [30] proposed a method that attempted to explain the formation and growth of transition-metal nanoparticles. This indirect method is based on an autocatalytic mechanism that considers a nudcation step in which a precursor A is converted to a zero-valent nuclei B with a rate constant fej, and a second step that considers the autocatalytic surface growth of the metal nanoparticles where species B catalyzes its own formation with a rate constant tc2 (Scheme 15.5). 

Polyoxoanions have received attention as models for oxide-supported transition metals, as novel catalytic materials, as imaging or labeling reagents for electron microscopy, and as inorganic drugs. The most difficult and slow step in such applications is often the synthesis and the full and unambiguous characterization of the desired polyoxoanion. 

Note finally that the esters just described can also be prepared by alcoholysis of the anhydride (Nb2W40i8)2 (see Scheme I). If the solution chemistry of polyoxoanions is to be regarded as a model for solid oxide reactivity, the esterification reaction corresponds to... 

MOLECULAR MODELS OF EARLY TRANSITION METAL OXIDES POLYOXOANIONS AS ORGANIC FUNCTIONAL GROUPS Victor W. Day, Walter G. Klemperer, Curtis Schwartz, and Ren-Chain Wang... 

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