Construction of Silver Clusters Capped by Zwitterionic Ethynide Ligands

A zwitterionic ligand 3-(triethylammonio)propyne (TAP) has been employed to construct nine silver ethynide compounds for the first time. Single-crystal X-ray analyses reveal that compounds 1 and 2 are silver ethynide assemblies based on the Ag-3 subunits and clusters 3-8 are small discrete clusters of Ag-3, Ag-6, Ag-8, and Ag-12, respectively, ligated by the bulky TAP ligand with different auxiliary ligands. In addition, upon acquiring the tripod-like (BuPO32-)-Bu-t, a unprecedented 80 nuclei silver ethynide cluster was isolated and determined to be [(CF3CO2)(5)@ Ag-80(TAP)(14)((BuPO3)-Bu-t)(16)(CF3CO2)(24)](19+) by crystallography and thermogravimetric analysis. The C-1 symmetry of Ag-80 was deconstructed to be two [Ag-40(TAP)(7)((BuPO3)-Bu-t)(8)(CF3CO2)(12)](12+) secondary building subunits arranged in a cross way, with five CF3CO2- trapped in the center. These results highlight that the elaborate selection of ethynide ligands is of great importance in the synthesis of novel silver ethynide clusters.

Automated summary

In this study, a zwitterionic ligand TAP was used to construct nine silver ethynide compounds, leading to the discovery of an unprecedented 80-nuclei silver ethynide cluster. The results emphasize the importance of careful selection of ethynide ligands in the synthesis of novel silver ethynide clusters.