Ag50(Dppm)6(SR)30 and Its Homologue AuxAg50-x(Dppm)6(SR)30 Alloy Nanocluster: Seeded Growth, Structure Determination, and Differences in Properties.

A large thiolate/phosphine coprotected Ag50(Dppm)6(SR)30 nanocluster was synthesized through the further growth of Ag44(SR)30 nanocluster and characterized by X-ray photoelectron spectroscopy (XPS), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray analysis. This new nanocluster comprised a 32-metal-atom dodecahedral kernel and two symmetrical Ag9(SR)15P6 ring motifs. The 20 valence electrons correspond to shell closure in the Jellium model. Moreover, this nanocluster could be alloyed by templated/galvanic metal exchange to the homologue AuxAg50-x(Dppm)6(SR)30 nanocluster; the latter showed much higher thermal stability than the Ag50(Dppm)6(SR)30 nanocluster. Further experiments were conducted to study the optical, electrical, and photoluminescence properties of both nanoclusters. Our work not only reports two new larger size nanoclusters but also reveals a new way to synthesize larger size silver and alloy nanoclusters, that is, controlled growth/alloying.