Superatom Pruning by Diphosphine Ligands as a Chemical Scissor

A two-electron silver superatom, [Ag6{S2P-(OiPr)2}4(dppm)2] (1), was synthesized by adding dppm (bis(diphenylphosphino)methane) into [Ag20{S2P(OiPr)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 Ag20 nanocluster (NC) to an octahedral Ag6 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.

Automated summary

A new method for achieving nanocluster-to-nanocluster transformation was discovered through stepwise synthesis. The added dppm ligands altered the geometry of the nanoclusters and reduced the electron count from eight to two. The resulting compound exhibited strong yellow fluorescence at room temperature.