Intercluster Reactions Resulting in Silver-Rich Trimetallic Nanoclusters

Herein, we present an intercluster reaction leading to new trimetallic nanoclusters (NCs) using bimetallic and monometallic NCs as reactants. Dithiol protected bimetallic MAg28(BDT)12(PPh3)4 (BDT = 1,3-benzenedithiol and M = Ni, Pd, or Pt) and monothiol protected Au25(PET)18 (PET = 2-phenylethanethiol) were used as model NCs. A mixture of trimetallic MAuxAg28–x(BDT)12(PPh3)4 (x = 1–12) and bimetallic AgxAu25–x(PET)18 (x = 1–7) NCs were formed during the reaction as understood from time-dependent electrospray ionization mass spectrometry (ESI MS). Detailed studies of intercluster reaction between Ag29(BDT)12(PPh3)4 and Au25(PET)18 were also performed. Although both MAg28(BDT)12(PPh3)4 (M = Ag, Ni, Pd, or Pt) and Au25(PET)18 contain 13 atoms icosahedral core, only a maximum of 12 Au doped NCs were formed for the former as a major product and not the 13 Au doped one, unlike the previous reports of intercluster reaction. The transfer of Ni, Pd, or Pt atom from the center of icosahedron of MAg28(BDT)12(PPh3)4 to Au25(PET)18 was not observed, which suggests that the central atom is not involved in the reaction. Density functional theory (DFT) calculations were performed to know structures and properties of the formed NCs. This study demonstrates the use of intercluster reaction as an effective synthetic protocol to make multimetallic alloy NCs.