Synthesis and catalytic applications of stable palladium dioxygen complexes

Article abstract of DOI:10.1021/om1003418

The synthesis and characterization of air-stable palladium dioxygen complexes Pd(O₂)L₂ of basic phosphines L = P(1-Ad) ₂ⁿBu, P^tBu₂ⁿBu is described. Contrary to general belief, these dioxygen complexes are stable catalyst precursors for palladium-catalyzed coupling reactions. Specifically, palladium-catalyzed formylations and alkoxy carbonylations of aryl bromides proceed in high yield in air using commercial non-degassed solvents. It is shown that Pd(O₂)L₂ complexes are reduced back to the catalytically active palladium(0) species in the reductive atmosphere of CO or H₂ at the onset of the carbonylation reaction.