[ACIE] 我室郑南峰教授发表论文:Highly Robust but Surface‐Active: N‐Heterocyclic Carbene‐Stabilized Au25 Nanocluster

发布日期:2019年09月14日   浏览次数:

我室郑南峰教授在 ACIE 上发表论文:Highly Robust but Surface‐Active: N‐Heterocyclic Carbene‐Stabilized Au25 Nanocluster



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. Herein, we report a novel N‐heterocyclic carbene‐stabilized Au25 nanocluster with high thermal and air stabilities 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 oC 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.