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JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol.141, no.10, pp.4460-4467, 2019 (SCI-Expanded)
The elaborate selection of capping ligands is of great importance in the synthesis of atomically precise metal nanoclusters. Organic thiolates, alkynyls, phosphines, and/or their combinations are the ligands most widely utilized to protect metal nanoclusters, while inorganic oxo anions have been almost neglected in this field. Herein, the first CrO42-/(BuC)-Bu-t C- co-capped Ag-48 nanocluster (SD/Ag48, SD = SunDi) was synthesized and structurally characterized by single-crystal X-ray diffraction. The pseudo-5-fold symmetric metal skeleton of SD/Ag48 shows a core shell structure composed of a Ag-23 cylinder encircled by an outer Ag-25 shell. Unprecedentedly, coexistence of inorganic (CrO42-) and organic ((BuC)-Bu-t C-) ligands was observed on the surface of SD/Ag48. The inorganic CrO42- anion plays three important roles in the construction of silver nanoclusters: (i) passivating the Ag-23 kernel; (ii) connecting the core and shell; and (iii) protecting the Ag-25 shell. This nanocluster belongs to a 14e superatom system and exhibits successive molecule-like absorption bands from the visible to the ultraviolet region. This work not only establishes a fresh inorganic ligand strategy in the synthesis of silver nanoclusters but also provides a new insight into the important surface coordination chemistry of CrO42- in the shape control of silver nanoclusters.