Background Generating a More Lewis Acidic Catalytic Center

CONCEPTUAL BACKGROUND GENERATING A MORE LEWIS ACIDIC CATALYTIC CENTER 

Metal complexes act as n acids (10) and are powerful tools for the activation of C—C multiple bonds—the key step for the initiation of many catalytic cycles involving C—C imsaturation. This process is facilitated by a more electrophilic metal center with an enhanced tendency to bind with the nucleophilic monomer. 

The electrophilic activation of a C—C multiple bond as a result of coordination to an electron-deficient metal ion is fundamental to much of organometallic chemistry, both conceptually and in synthetic applications (11). The Wacker process, a classic example of an efficient catalytic oxidation, is an important industrial reaction, used for the conversion of ethylene into acetaldehyde. The catalytic reaction begins with the coordination of ethylene to a Pd(ll) center, leading to activation of the ethylene moiety. The key step is the reaction of the metal-olefin complex with a nucleophile to give substituted metal-alkyl species (12). The integration of this reaction into a productive catalytic cycle requires the eventual cleavage of the newly generated M—C bond. 

The activation of C—C multiple bonds essentially involves electron donation via a coordinate bond to the empty orbital on the metal and a 7i-back donation from the metal to empty n orbitals on carbon atoms resulting in the well-known s)mergetic effect (13). As a result of these interactions, C—C multiple bonds are activated. 

ATTACHMENT OF THE OXYGEN CENTER AROUND THE ACTIVE METAL DEVELOPMENT OF MOLECULAR CATALYSTS BASED ON THE M—O—M MOTIF 

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