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.