Au130−xAgx Nanoclusters with Non‐Metallicity: A Drum of Silver‐Rich Sites Enclosed in a Marks‐Decahedral Cage of Gold‐Rich Sites

• Published in: Angewandte Chemie International Edition Vol. 58; no. 52; pp. 18798 - 18802
• Main Authors: Higaki, Tatsuya, Liu, Chong, Morris, David J., He, Guiying, Luo, Tian‐Yi, Sfeir, Matthew Y., Zhang, Peng, Rosi, Nathaniel L., Jin, Rongchao
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 19.12.2019
• Edition: International ed. in English
• Subjects: Absorption; Absorption spectra; alloys; Bimetals; Bonding strength; Cages; crystal structure; electron dynamics; Fine structure; Gold; Metallicity; Nanoclusters; Silver; Structural analysis; Supports; Ultrastructure; X-ray spectroscopy
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201908694

The synthesis and structure of atomically precise Au130−xAgx (average x=98) alloy nanoclusters protected by 55 ligands of 4‐tert‐butylbenzenethiolate are reported. This large alloy structure has a decahedral M54 (M=Au/Ag) core. The Au atoms are localized in the truncated Marks decahedron. In the core, a drum of Ag‐rich sites is found, which is enclosed by a Marks decahedral cage of Au‐rich sites. The surface is exclusively Ag−SR; X‐ray absorption fine structure analysis supports the absence of Au−S bonds. The optical absorption spectrum shows a strong peak at 523 nm, seemingly a plasmon peak, but fs spectroscopic analysis indicates its non‐plasmon nature. The non‐metallicity of the Au130−xAgx nanocluster has set up a benchmark to study the transition to metallic state in the size evolution of bimetallic nanoclusters. The localized Au/Ag binary architecture in such a large alloy nanocluster provides atomic‐level insights into the Au−Ag bonds in bimetallic nanoclusters. Au130−xAgx(TBBT)55 is synthesized and structurally characterized. The large bimetallic nanocluster exhibits localization of Au atoms to form a Marks decahedron; fs spectroscopy reveals that this nanocluster is non‐metallic. XAFS analysis revealed charge transfer within the core. The observed structure and properties have provided insights into the structural rule, alloying patterns, and non‐metallicity.