All‐ <i>Nido</i> ‐Carborane‐Protected Copper Clusters

Abstract Peripheral ligands of metal nanoclusters play a crucial role in determining their structures and modulating their physicochemical properties. Therefore, expanding the diversity of ligands is of paramount importance for advancing metal cluster science. In this work, we report for the first time the synthesis and characterization of two all‐ nido ‐carborane‐protected copper nanoclusters: an octahedral [Cu 6 (C 2 B 9 H 11 ) 4 ](Et 4 N) 2 ( Cu 6 ) and an icosahedral [Cu 13 (C 2 B 9 H 11 ) 6 ](Et 4 N) 3 ( Cu 13 ) (Et 4 N = tetraethylammonium). As confirmed by ESI‐MS and time‐dependent UV–vis absorption spectroscopy, Cu 6 undergoes spontaneous transformation into Cu 13 in acetone solution. Theoretical computations reveal that the superatomic cluster Cu 13 possesses an open‐shell electronic structure of 1S 2 1P 2 . Moreover, Cu 13 solution exhibits prominent near‐infrared luminescence at 880 nm and demonstrates superior performance in bioimaging with 4T1 cells, showcasing significant potential for biomedical applications. This study not only enriches the ligand library for metal clusters but also provides new impetus for the exploration of carborane chemistry.