Pd-Mediated Synthesis of Ag_(33) Chiral Nanocluster with Core-Shell Structure in T Point Group

摘要

We report a Pd-mediated synthesis and crystal structure of a new chiral Ag-33(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 Ag-13 icosahedron core with one Ag atom in the center and a shell framework of Ag20S24 P-4 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 Ag-33 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 Ag-33 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.