Reducing agents transition metals

Hydrogen peroxide, in combination with reducing agents (transition metals), also is used in those appHcations where its high water- and low od-solubiHty is not a problem or is easily overcome. 

Group 14 metal hydrides, especially those of silicon and tin, are satisfactory nonreactive hydride donors, as in the absence of a catalyst they are, generally, poor reducing agents. Transition metal complexes are attractive transfer agents because they insert readily into Si—H or Sn—bonds and they also bind specifically to various functional groups. 

The CO molecule is a well-known coordinating ligand for many transition metals. Although CO has been reported to be a reducing agent for metal ions such as Cu " and Ag" in zeolites (214,215), it also induces oxidative redispersion of Rh particles in zeolites at room temperature (704). With FTIR, it has been established that the presence of H2O is crucial for the reduction of Ag" in zeolite according to the following reaction ... 

The aluminiun compoimd alkylates the transition metal and can act as a transfer agent. It also removes impurities from the reaction medium (eg, water, CO2, alcohols), thereby avoiding catalyst poisoning. In addition, aluminiun alkyl reduces the transition metal to lower valence, thus affecting its activity (210). In the case of supported catalysts, aluminum alkyl plays a fundamental role by complexing the electron donors (204). 

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