Surface Coordination of Multiple Ligands Endows N‐Heterocyclic Carbene‐Stabilized Gold Nanoclusters with High Robustness and Surface Reactivity

Abstract

Deciphering the molecular pictures of the multi‐component and non‐periodic organic‐inorganic interlayer is a grand technical challenge. Here we show that the atomic arrangement of hybrid surface ligands on metal nanoparticles can be precisely quantified through comprehensive characterization of a novel gold cluster, Au44(iPr2‐bimy)9(PA)6Br8 (1), which features three types of ligands, namely, carbene (1,3‐diisopropylbenzimidazolin‐2‐ylidene, iPr2‐bimy), alkynyl (phenylacetylide, PA), and halide (Br), respectively. The delicately balanced stereochemical effects and bonding capabilities of the three ligands give rise to peculiar geometrical and electronic structures. Remarkably, despite its complex and highly distorted surface structure, cluster 1 exhibits unusual catalytic properties and yet it is highly stable, both chemically and thermally. Moreover, rich reactive sites on the cluster surface raise the prospect of bio‐compatibility (as it can be functionalized to yield water‐soluble derivatives) and bio‐applications.

Catalytically Active Gold Nanomaterials Stabilized byN‐heterocyclic Carbenes

“…Poisoning tests with CO confirmed the importance of accessible surface gold atoms for the catalytic activity. Further, NHC@AuNCCat ⋅ 4 showed substrate selectivity towards aromatic alkynes [63b] …”

NHC-Stabilized Au10 Nanoclusters and Their Conversion to Au25 Nanoclusters

“… 9 − 15 Known NHC-stabilized gold nanoclusters are predominantly smaller Au 11 or Au 13 species, 16 − 20 however, Au 23 and Au 44 cores have also been reported for mixed-ligand systems. 21 , 22 Despite the high prevalence of Au 25 cores in thiolate-stabilized clusters, there is only one example of this cluster size for NHC-stabilized systems. 23 …”

Synthesis and enantioseparation of chiral Au13 nanoclusters protected by bis-N-heterocyclic carbene ligands

“… 17,18 Zheng et al have also described the synthesis of Au 13 , 19 Au 25 (ref. 20 a ) and Au 44 (ref. 20 b ) nanoclusters, and Tsukuda has prepared Au 23 clusters, 21 illustrating the potential of NHCs as stabilizing ligands for a range of gold nanocluster architectures.…”