An Intermetallic Au₂₄Ag₂₀ Superatom Nanocluster Stabilized by Labile Ligands

Abstract

An intermetallic nanocluster containing 44 metal atoms, Au24Ag20(2-SPy)4(PhC≡C)20Cl2, was successfully synthesized and structurally characterized by single-crystal analysis and density funtional theory computations. The 44 metal atoms in the cluster are arranged as a concentric three-shell Au12@Ag20@Au12 Keplerate structure having a high symmetry. For the first time, the co-presence of three different types of anionic ligands (i.e., phenylalkynyl, 2-pyridylthiolate, and chloride) was revealed on the surface of metal nanoclusters. Similar to thiolates, alkynyls bind linearly to surface Au atoms using their σ-bonds, leading to the formation of two types of surface staple units (PhC≡C-Au-L, L = PhC≡C(-) or 2-pyridylthiolate) on the cluster. The co-presence of three different surface ligands allows the site-specific surface and functional modification of the cluster. The lability of PhC≡C(-) ligands on the cluster was demonstrated, making it possible to keep the metal core intact while removing partial surface capping. Moreover, it was found that ligand exchange on the cluster occurs easily to offer various derivatives with the same metal core but different surface functionality and thus different solubility.

Bridging the Gap: Electron Relay and Plasmonic Sensitization of Metal Nanocrystals for Metal Clusters

“…17,18 When the size of metal NPs becomes atomically small (< 2 nm), with precise number of metal atoms and protected by a stabilizing ligand, they are referred to as "metal clusters". [19][20][21][22][23][24][25] Contrary to metal NPs, metal clusters are featured by peculiar atom packing, effect of quantum confinement, and discrete molecule-like band structure.…”

Atomically Tailored Gold Nanoclusters for Catalytic Application

“…While the majority of such correlated NCs are protected by thiolate ligands,t here are also af ew cases protected by non-thiolate ligands,s uch as selenolate [12] or alkynyl. [13] Forcatalytic applications,the NCs with size and/or structural similarities are desired as they can provide ap latform with which to obtain deeper insight into the respective role of the kernel, staples,o rl igands on the catalytic performance.…”

Identification of an Eight-Electron Superatomic Cluster and Its Alloy in One Co-crystal Structure

“…Prominent silver/gold alloy examples being structurally characterized include Au 25-x Ag x [10], Au 38-x Ag x [11], Au 24 Ag 20 [12], Au 24 Ag 46 [13], Au 12 Ag 32 [3b], Au 25 Ag 2 [14], Ag 28 Au [15], Au 12 Ag 13 [16], Au 80 Ag 30 [17], Au 3 Ag 38 [18], Au 7 Ag 8 [19], and Au x Ag y [20] + via a galvanic replacement method [22]. Despite the tremendous progresses in their synthesis and characterization, the mechanistic studies for the formation of Ag alloy NCs are lagged significantly behind.…”