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.