Superatom Pruning by Diphosphine Ligands as a Chemical Scissor.

A two-electron silver superatom, [Ag 6 {S 2 P(O i Pr) 2 } 4 (dppm) 2 ] ( 1 ), was synthesized by adding dppm (bis(diphenylphosphino)methane) into [Ag 20 {S 2 P(O i Pr) 2 } 12 ] (8e). It was characterized by single-crystal crystallography, multinuclear NMR spectroscopy, electrospray ionization-mass spectrometry, density functional theory (DFT), and time-dependent DFT calculations. The added dppm ligands, which carry out the nanocluster-to-nanocluster transformation, act as a chemical scissor to prune the nanocluster geometrically from an icosahedron-based Ag 20 nanocluster (NC) to an octahedral Ag 6 NC and electronically from eight-electron to two-electron. Eventually, dppm was involved in the protective shell to form a new heteroleptic NC. The temperature-dependent NMR spectroscopy confirms its fluxional behavior, showing the fast atomic movement at ambient temperature. Compound 1 exhibits a bright yellow emission under UV irradiation at ambient temperature with a quantum yield of 16.3%. This work demonstrates a new methodology to achieve nanocluster-to-nanocluster transformation via stepwise synthesis.