Highly Robust but Surface‐Active: An N‐Heterocyclic Carbene‐Stabilized Au25 Nanocluster |
| |
Authors: | Hui Shen Guocheng Deng Sami Kaappa Tongde Tan Ying‐Zi Han Sami Malola Shui‐Chao Lin Boon K Teo Hannu Hkkinen Nanfeng Zheng |
| |
Institution: | Hui Shen,Guocheng Deng,Sami Kaappa,Tongde Tan,Ying‐Zi Han,Sami Malola,Shui‐Chao Lin,Boon K. Teo,Hannu Häkkinen,Nanfeng Zheng |
| |
Abstract: | Surface organic ligands play a critical role in stabilizing atomically precise metal nanoclusters in solutions. However, it is still challenging to prepare highly robust ligated metal nanoclusters that are surface‐active for liquid‐phase catalysis without any pre‐treatment. Now, an N‐heterocyclic carbene‐stabilized Au25 nanocluster with high thermal and air stabilities is presented as a homogenous catalyst for cycloisomerization of alkynyl amines to indoles. The nanocluster, characterized as Au25(iPr2‐bimy)10Br7]2+ (iPr2‐bimy=1,3‐diisopropylbenzimidazolin‐2‐ylidene) ( 1 ), was synthesized by direct reduction of AuSMe2Cl and iPr2‐bimyAuBr with NaBH4 in one pot. X‐ray crystallization analysis revealed that the cluster comprises two centered Au13 icosahedra sharing a vertex. Cluster 1 is highly stable and can survive in solution at 80 °C for 12 h, which is superior to Au25 nanoclusters passivated with phosphines or thiols. DFT computations reveal the origins of both electronic and thermal stability of 1 and point to the probable catalytic sites. This work provides new insights into the bonding capability of N‐heterocyclic carbene to Au in a cluster, and offers an opportunity to probe the catalytic mechanism at the atomic level. |
| |
Keywords: | Au25 Carbenliganden Goldkatalyse Goldnanocluster Homogene Katalyse |
|
|