Pd-Mediated Synthesis of Ag₃₃ Chiral Nanocluster with Core-Shell Structure in T Point Group

We report a Pd-mediated synthesis and crystal structure of a new chiral Ag₃₃(SCH₂CH₂Ph)₂₄(PPh₃)₄ nanocluster with an open shell electronic structure. The single-crystal X-ray structure reveals that the kernel of the cluster comprises a keplerate Ag₁₃ icosahedron core with one Ag atom in the center and a shell framework of Ag₂₀S₂₄P₄ block. The Ag₂₀S₂₄P₄ shell framework is fully arranged by helical -S-Ag-S- staples along four Ag-P bonds involved C3 axis, which endows the kernel structure of the nanocluster chirality and symmetry in the T point group. The geometry and chirality of the Ag₃₃ nanocluster are further confirmed by nuclear magnetic resonance (NMR), electronic circular dichroism (ECD) spectra, and time-dependent density functional theory calculations. Our results show that the formation of the new chiral Ag₃₃ nanocluster is strongly dependent on the presence of Pd regent with the form of Pd(PPh₃)₄ functioning in the synthesis. This work not only presents a novel chiral structure of the silver nanocluster but also provides a new strategy for the development of a novel nanocluster.