清华大学王泉明团队开发了簇合催化中稳定性与活性平衡的配体工程。相关研究成果发表在2022年1月10日出版的《德国应用化学》。

研究人员报道两种Ag21纳米团簇的结构、稳定性和催化性能，即[Ag21(H2BTCA)3(O2PPh2)6]SbF6(1)和[Ag21(C≡CC 6 H 3-3,5-R 2)6(O2 PPh2)10]SbF6(2)(H4BTCA=对叔丁基二甲酰胺[4]芳烃，R=OMe）。两种Ag21都具有相同的二十面体核，由八个外围Ag原子包围。单晶结构分析和ESI-MS表明，1是一个8电子团簇，2有四个自由电子。

理论结果表明，P对称轨道在1中被发现为HOMO-1和HOMO态，前线未占据分子轨道（LUMO、LUMO+1和LUMO+2）呈现D-特征，表明1是一个具有电子闭合壳层1S21P6的超原子簇，而2具有不完全壳层结构1S21P2。两个Ag21团簇在环境条件下表现出优异的稳定性，并且1即使在甲苯中的90°C和氧化条件下（30%H2O2）也很稳定。值得注意的是，2在还原4-硝基苯酚方面表现出比1高得多的活性。

研究工作表明，配体可以干扰银簇的电子结构，进而影响其稳定性和催化性能。

附：英文原文

Title: Ligand Engineering toward the Trade-off between Stability and Activity in Cluster Catalysis

Author: Zong-Jie Guan, Rui-Lin He, Shang-Fu Yuan, Jiao-Jiao Li, Feng Hu, Chun-Yu Liu, Quan-Ming Wang

Issue&Volume: 2022-01-10

Abstract: We report the structures, stability and catalysis properties of two Ag  21  nanoclusters, namely [Ag  21  (H  2  BTCA)  3  (O  2  PPh  2  )  6  ]SbF  6  (  1  ) and [Ag  21  (C≡CC  6  H  3  -3,5-R  2  )  6  (O  2  PPh  2  )  10  ]SbF  6  (  2  ) (H  4  BTCA =  p  -  tert  -butylthiacalix[4]arene, R = OMe). Both Ag  21  possess identical icosahedral kernel that is surrounded by eight peripheral Ag atoms. Single-crystal structural analysis and ESI-MS revealed that  1  is an 8-electron cluster and  2  has four free electrons. Theoretical results show that the P-symmetry orbitals are found as HOMO-1 and HOMO states in  1  , and the frontier unoccupied molecular orbitals (LUMO, LUMO+1 and LUMO+2) show D-character, indicating  1  is a superatomic cluster with an electronically closed shell 1S  2  1P  6  while  2  has an incomplete shell configuration 1S  2  1P  2  . These two Ag  21  clusters show superior stability under ambient conditions, and  1  is robust even at 90°C in toluene and under oxidative conditions (30% H  2  O  2  ). Significantly,  2  exhibits much higher activity than  1  as catalysts in the reduction of 4-nitrophenol. This work demonstrates that ligands can interfere the electronic structures of silver clusters, and further affect their stability and catalytic performance.

DOI: 10.1002/anie.202116965

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202116965