Evidence for heterogeneous Sonogashira coupling of phenylacetylene and iodobenzene catalyzed by well defined rhodium nanoparticles.

Sonogashira coupling of phenylacetylene with iodobenzene has been studied in the presence of metallic Rh nanoparticle catalysts and found to occur via a surface-mediated heterogeneous route. Homogeneous catalytic processes due to Rh species that may leach into solution were barely detectable within the sensitivity of our experiments. Moreover, larger (8 nm) nanoparticles were found to be much better catalysts than very small ones (2 nm), which is consistent with the hypothesis that steric limitations adversely affect the efficiency of the latter.