Cobalt Nanoparticles on Charcoal:  A Versatile Catalyst in the Pauson−Khand Reaction, Hydrogenation, and the Reductive Pauson−Khand Reaction

[formula: see text] Dispersions of nanometer-sized cobalt particles with very high stability were prepared in charcoal and analyzed by electron microscopy and X-ray analysis. The resulting cobalt nanoparticles on charcoal (CNC) were successfully used as a catalyst for the carbonylative cycloaddition of alkyne, alkene, and carbon monoxide (Pauson-Khand reaction), hydrogenation, and the reductive Pauson-Khand reaction.