A nanoscopic icosahedral {Mo 72 Fe 30 } cluster catalyzes the aerobic synthesis of benzimidazoles.

In this study, the catalytic efficiency of amorphous {Mo 72 Fe 30 } nanocapsules as a safe Keplerate polyoxometalate in organic synthesis was exploited. The easy-made solid catalyst exhibited high efficiency using a very low dosage (0.02-0.05 mol%) in the catalyzed condensation of various aromatic 1,2-diamines and aldehydes for the aerobic synthesis of benzimidazoles with very small E -factor values (0.11-0.33). The superior catalytic activity of amorphous nanoclusters compared to that of its crystalline counterpart was demonstrated. The high activity and recyclability of heterogeneous catalysts in a green reaction media under oxygen atmosphere, make this environmentally benign organic process appropriate for our applied goals.