Motif-to-Core Nucleation in a Decahedral Evolution Pattern.

The atomic precision of ultrasmall metal nanoclusters has opened the door to elucidating the structural evolution principles of metal nanomaterials at the molecular level. Here, we report a novel set of super-atomic Ag clusters, including [Ag 19 (TBBT) 16 (DPPP) 4 ] + (Ag 19 ), [Ag 22 (DMAT) 8 (DPPM) 4 Cl 8 ] 2+ (Ag 22 ), Ag 26 (SPh 3,5- CF 3 ) 15 (DPPF) 4 Cl 5 (Ag 26 ), and [Ag 30 (DMAT) 12 (DPPP) 4 Cl 8 ] 2+ (Ag 30 ). The core structures of these clusters correspond to one decahedral Ag 7 , perpendicular bi-decahedrons, three-dimensional penta-decahedrons, and hexa-decahedrons, respectively. The Ag atoms in AgS 2 blocks show a strong correlation with the decahedral cores: the five equatorial Ag atoms in the decahedral Ag 7 core of Ag 19 all adopt the AgS 2 coordination, while the Ag atoms in AgS 2 blocks of Ag 22 , Ag 26 , and Ag 30 unexceptionally constitute additional decahedral structures with the core Ag atoms. Specifically, two and four core Ag atoms of Ag 26 and Ag 30 clusters occupy positions that highly resemble that of Ag (in AgS 2 motifs) of Ag 22 . The strong structural correlation demonstrates the motif-to-core evolution of the surface Ag (on AgS 2 ) to build extra-decahedral blocks. Density functional theory calculations indicate that the 2e, 4e, 6e, and 8e clusters (from Ag 19 to Ag 30 ) adopt 1S 2 , 1S 2 1P 2 , 1S 2 1P 4 , and 1S 2 1P 6 electron configurations, all of which feature excellent super-atomic characters.