Gold Catalysis Revisited

Transition-metal complexes with one or more gold atoms need help to catalyze cross-couplings such as the Sonogashira reaction, but gold nanoparticles can go it alone, according to work from a team led by Avelino Corma of Spain’s Polytechnic University of Valencia (Chem. Commun., DOI: 10.1039/c0cc04564k). Last year, Antonio M. Echavarren of Spain’s Institute of Chemical Research of Catalonia and coworkers questioned several groups’ work, including Corma’s, on gold complexes catalyzing the Sonogashira reaction, suggesting that palladium impurities were crucial for the process (C&EN, July 26, 2010, page 41). Corma’s team has now performed kinetic and theoretical studies that suggest gold nanoparticles catalyze the reaction without help from palladium. The researchers also revisited reactivity they reported was catalyzed by gold complexes and found evidence of gold nanoparticle formation over time, suggesting nanoparticle catalysis. Echavarren says the new work is in agreement with both other groups’ work on gold nanoparticles and his team’s study. Organometallic chemist A. Stephen K. Hashmi of the University of Heidelberg, in Germany, adds that it’s not surprising that the groups find different catalytic behavior because they are dealing with very different gold species. “I think both teams are right,” Hashmi says.