Surface-Mediated Organometallic Syntheses

From Surface Organometallic Chemistry to Surface-Mediated Organometallic Synthesis... 

The specific characteristics of a surface such as silica, if considered as a new reaction medium, were confirmed by the unusual selectivity and easy reactivity shown in so-called surface-mediated organometallic synthesis. 

The evidence, produced already in the early 1980s, that monometallic surface species like Os " or Rh carbonyl fragments, incapsulated into the surface of silica or alumina, may have the necessary mobility to react with each other, since they return quite easily under a CO atmosphere to the original clusters Os3(CO)i2 and Rh6(CO) respectively [26, 27, 31], was the origin of so-called surface mediated organometallic synthesis. 

Roberto, D., Cariati, E., Ugo, R., and Psaro, R., Surface-mediated organometallic synthesis High-yield preparations of neutral and anionic osmium carbonyl clusters by controlled reduction of silica-supported [Os(CO)3Cl2]2 and OsClj in the presence of Na2C03 or K2C03. Inorg. Chem. 35,2311 (1996). 

I 76 Surface-Mediated Organometallic Syntheses Table 16.5 Traditional synthesis of Os metal carbonyl complexes and clusters in solution". 

The field of surface-mediated synthesis of metal carbonyl clusters has developed briskly in recent years [4-6], although many organometallic chemists still seem to be unfamiliar with the methods or consider themselves ill-equipped to carry them out. In a typical synthesis, a metal salt or an organometallic precursor is brought from solution or the gas phase onto a high-area porous metal oxide, and then gas-phase reactants are brought in contact with the sample to cause conversion of the surface species into the desired products. In these syntheses, characteristics such as the acid-base properties of the support influence fhe chemisfry, much as a solvenf or coreactant influences fhe chemisfry in a convenfional synfhesis. An advanfage of... 

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