Trimetallic AuAgPd and tetrametallic AuAgCuPd clusters were synthesized by the subsequential metal exchange reactions of dodecanethiolate-protected AuPd clusters. EXAFS measurements revealed that Pd, Ag, and Cu dopants preferentially occupy the center and edge sites of the core, and staple sites, respectively. Spectroscopic and theoretical studies demonstrated that the synergistic effects of multiple substitutions on the electronic structures are additive in nature.

This study demonstrates that controlling intra-cluster ligand interactions is important to obtain an assembled structure with the desired connecting structures.

The mixing of heteroelements in metal clusters is a powerful approach to generate new physical/chemical properties and functions. However, as the kinds of elements increase, control of the chemical composition and geometric structure becomes difficult. We succeeded in the compositionally selective synthesis of phenylethanethiolate-protected trimetallic AuAgPd and AuAgPt clusters, AuAgPd(SCHPh) and AuAgPt(SCHPh). Single-crystal X-ray structural analysis revealed the precise position of each metal element in these metal clusters. Reacting with thiol at an elevated temperature was found to be important to direct the metal elements to the most stable positions. The electronic structures of these trimetallic clusters become more discretized than those of the related bimetallic clusters due to orbital splitting.