A Critical Review on Carbon-Carbon Coupling over Ultra-Small Gold Nanoclusters

Well-defined gold nanoclusters have been documented as new and promising materials in the field of nanoscience. They have been well explored for the nanocatalysis of reactions like selective oxidation and hydrogenation, carbon-carbon coupling, etc. These Au nanoclusters possess unique electronic properties and crystal structure, which provide an excellent opportunity to correlate atomic structure with intrinsic catalytic property and to investigate the mechanisms of reactions over Au nanoclusters. In this review, we generalize the catalytic application of gold nanoclusters in carbon-carbon coupling reactions, including Ullmann, Sonogashira, Suzuki, and A(3)-coupling reactions. Herein, we have discussed ligand engineering (e.g., aromatic and aliphatic thiolate) as well as the effect of metal dopants (e.g., Cu, Ag, Pt, and Pd). Finally, the tentative catalytic mechanisms and the structure-performance relationships were discussed at the atomic level, which will give some clue for the design of efficient gold cluster catalysts.