ELECTROCHEMICAL REDUCTION OF CO2 CATALYZED BY SMALL ORGANOPHOSPHINE DENDRIMERS CONTAINING PALLADIUM

The sequential addition of diethyl vinylphosphonate to primary phosphines followed by reduction with lithium aluminum hydride can be used to synthesize small dendrimers containing up to 15 phosphorus atoms. A second approach uses the addition of bis((diethylphosphino)ethyl)phosphine to tetravinylsilane to produce a dendrimer containing 12 phosphorus atoms. The connectivities of these ligands are established unambiguously by P-31 NMR spectroscopy. These dendrimers react with [Pd(CH3CN)(4)](BF4)(2) to produce metalated dendrimers which catalyze the electrochemical reduction of CO2 to CO. Relationships between catalytic properties and dendrimer structure are discussed.