Linear Size Contraction of Ligand Protected Ag₂₉ Clusters by Substituting Ag with Cu

Abstract

There are only a few examples of atomically precise, ligand protected, bimetallic coinage metal clusters in which molecular structure remains essentially unchanged over a wide composition range starting from the corresponding homometallic species. Such model systems are particularly useful to study the dynamics of alloy formation on the nanoscale. Here we demonstrate the unusual reactivity of solvated metalloid-superatom Ag29(BDT)12(PPh3)4 (BDT = 1,3 benzenedithiol) clusters toward semiconducting Cu12S6(DPPPT)4 (DPPPT = bis­(diphenylphosphino)­pentane) clusters as an efficient way to exchange multiple copper atoms into the atomically precise silver clusters without changing overall the structure type. Concentration-dependent UV–vis absorption and online mass spectrometry shows that 14 Cu atoms can be exchanged into the silver cluster. Beyond the 14 Cu atom exchange, the cluster degrades to smaller thiolates. Information on cluster structures is obtained from high-resolution ion mobility mass spectrometry, which shows a linear decrease in collision cross section (CCS) with each Ag/Cu exchanged. Several isomeric structures are calculated by density functional theory (DFT), and their calculated collision cross sections are used to identify the most stable isomers for each Ag/Cu exchange product. Ag/Cu exchange is essentially limited to the cluster surface/shell. The core appears not to be involved.

Symmetry Breaking of Atomically Precise Fullerene-like Metal Nanoclusters

“…Responding to the "copper intruders", the shells of the nanoclusters continually contracted with increasing numbers of Cu atoms (Figure 1c). 47 In Ag 13 @Ag 16 Cu 4 , two of the Cu atoms with full occupancy mainly replaced the middle Ag atoms of the S−Ag− S−Ag−S−Ag−S chains, and are tetrahedrally coordinated with three S atoms and a CH 3 CN (ACN), forming the Cu-(SR) 3 CH 3 CN motif (Figures 1b, S10 and S11). Because higher coordination numbers are preferred by copper compared to silver, the atomic radius of copper is smaller than that of silver, and the metallophilic interaction of copper is weaker; the interatomic distances are also correspondingly adjusted.…”

“…The triad of coinage-metal nanoclusters is structurally similar to fullerenes, ,, as they all have a centered-icosahedron@dodecahedron core–shell structure that is protected and rigidified by 12 dithiolate ligands. Responding to the “copper intruders”, the shells of the nanoclusters continually contracted with increasing numbers of Cu atoms (Figure c) . In Ag 13 @Ag 16 Cu 4 , two of the Cu atoms with full occupancy mainly replaced the middle Ag atoms of the S–Ag–S–Ag–S–Ag–S chains, and are tetrahedrally coordinated with three S atoms and a CH 3 CN (ACN), forming the Cu­(SR) 3 CH 3 CN motif (Figures b, S10 and S11).…”

Isotopic Exchange of Atomically Precise Nanoclusters with Materials of Varying Dimensions: From Nanoscale to Bulk

“…Intercluster reactions have established that NCs can react just as molecules. ,, Au 25 (SR) 18 – and Ag 44 (SR) 30 4– (SR is a thiolate ligand) react spontaneously to form alloy NCs as the product . Similar reactions were also observed between Au 25 (SR) 18 – and Ag 25 (SR) 18 – . , Intercluster reactions were also used to create bimetallic ,, and trimetallic NCs . Literature studies suggest that a possible route of such reactions is through the exchange of metal or metal–ligand fragments .…”

Total Structure of Bimetallic Core–Shell [Au42Cd40(SR)52]2− Nanocluster and Its Implications

“…Bimetallic NCs often show unique properties compared to homo‐metallic ones owing to the synergy between constituent metals and the modified electronic structure [2–5] . There have been reports of incorporating different heterometals into gold NCs [3, 6–10] . These bimetallic NCs are also applied in bio‐sensing and catalysis with significantly enhanced functionalities [2, 11–17] …”

“…[2][3][4][5] There have been reports of incorporating different heterometals into gold NCs. [3,[6][7][8][9][10] These bimetallic NCs are also applied in bio-sensing and catalysis with significantly enhanced functionalities. [2,[11][12][13][14][15][16][17] In thiolate-protected gold-based bimetallic NCs, a general trend of the distribution of metal elements is that the surface is typically composed of the less noble metal with low valence state, such as Ag I and Cu I , resembling Au I in homo gold NCs.…”