Guan Zong-Jie, He Rui-Lin, Yuan Shang-Fu, Li Jiao-Jiao, Hu Feng, Liu Chun-Yu, Wang Quan-Ming
Department of Chemistry, Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing, 100084, P.R. China.
Angew Chem Int Ed Engl. 2022 Mar 7;61(11):e202116965. doi: 10.1002/anie.202116965. Epub 2022 Jan 24.
We report the structures, stability and catalysis properties of two Ag nanoclusters, namely [Ag (H BTCA) (O PPh ) ]SbF (1) and [Ag (C≡CC H -3,5-R ) (O PPh ) ]SbF (2) (H BTCA=p-tert-butylthiacalix[4]arene, R=OMe). Both Ag structures possess an 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 1P , while 2 has an incomplete shell configuration 1S 1P . These two Ag clusters show superior stability under ambient conditions, and 1 is robust even at 90 °C in toluene and under oxidative conditions (30 % H O ). Significantly, 2 exhibits much higher activity than 1 as catalyst in the reduction of 4-nitrophenol. This work demonstrates that ligands can influence the electronic structures of silver clusters, and further affect their stability and catalytic performance.
我们报道了两个银纳米团簇，即[Ag (H BTCA) (O PPh ) ]SbF (1) 和[Ag (C≡CC H -3,5-R ) (O PPh ) ]SbF (2)（H BTCA = 对叔丁基硫杂杯[4]芳烃，R = OMe）的结构、稳定性和催化性能。两种银结构都具有相同的二十面体核，该核被八个外围银原子包围。单晶结构分析和电喷雾电离质谱显示1是一个8电子团簇，2有四个自由电子。理论结果表明，在1中P对称轨道为HOMO - 1和HOMO态，前沿未占据分子轨道（LUMO、LUMO + 1和LUMO + 2）显示D特征，表明1是一个具有电子封闭壳层1S 1P的超原子团簇，而2具有不完全壳层构型1S 1P。这两个银团簇在环境条件下表现出优异的稳定性，1即使在甲苯中90°C和氧化条件（30% H O ）下也很稳定。值得注意的是，在4 - 硝基苯酚还原反应中，2作为催化剂表现出比1高得多的活性。这项工作表明配体可以影响银团簇的电子结构，并进一步影响它们的稳定性和催化性能。
