Recently, a group led by Prof. LI GAO from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences, in collaboration with Prof. WAN Chongqing from Capital Normal University and Prof. Hannu Hakkinen from University of Jyvaskyla, synthesized a novel atomically precise AuAg cluster with special structure, which is exploited as a model catalyst for A3-coupling reactions.
This work was published in Angew. Chem. Int. Ed. on September 30.
Total structure and negative-mode ESI mass spectrum of the Au13Ag16L24 cluster, the Au@Ag12@Au12Ag4 metal framework protected by alkyne groups from 24 ligands (Image by QIN Zhaoxian)
The scientists prepared a brand new alkynylated cluster [Au13Ag16(C10H6NO)24]3- by NaBH4 mediated reduction method. And confirmed the AuAg clusters by various sophisticated characterization techniques. They found that the unique metal framework of "Aucenter@Ag12@Au12Ag4" was protected by 24 atypical alkyne ligands L (L = C10H6NO).
The ligands were found to construct a unique type of motif L-(Ag)-Au-(Ag)-L at the cluster interface, where, the alkyne (C≡C) group of each L was linked by sharing an Au atom through the σ bonds and each C≡C group was discretely connected to chemically different Ag atom through π bonds.
DFT characterized the cluster as a clear 8-electron superatom, and peaks in the optical absorption spectrum were interpreted in terms of the P and D superatom states. The supported Au13Ag16L24/CeO2 catalyst exhibited high catalytic activity and selectivity towards the A3-coupling reaction involving benzaldehyde, diethylamine and phenylacetylene.
This work was supported by Liaoning Natural Science Foundation of China, and Liaoning Revitalization Talents Program. (Text by QIN Zhaoxian)