Eight-electron copper-hydride nanoclusters: synthesis, structure, alloying chemistry and photoluminescence

The first copper-hydride nanocluster featuring eight free valence electrons has been successfully isolated and characterized spectroscopically. The structure of the nanocluster, represented by the chemical formula [Cu₄₇(PhSe)₁₅(PPh₃)₅(CF₃COO)₁₂H₁₂] (referred to as Cu₄₇H₁₂, where PPh₃ denotes triphenylphosphine), has been precisely determined through single crystal X-ray diffraction analysis. Several distinguishing features differentiate the Cu₄₇H₁₂ clusters from previously reported examples. In terms of composition, these clusters represent a rare instance of high-nuclearity Cu nanoclusters containing hydride and stabilized by selenolate ligands. From an electronic standpoint, the stabilization of the nanocluster is achieved through its eight free valence electrons, marking it as the first copper-hydride cluster with this configuration. The alloying chemistry of the nanocluster also introduces unexpected findings in the field. The incorporation of silver atoms leads to the formation of [(CuAg)₄₇(PhSe)₁₈(PPh₃)₆(CF₃COO)₁₂H₆]³⁺ clusters, which exhibit significant structural differences from the parent cluster. Both the homo and alloy clusters display dual-emission properties at 298 K, with the clusters additionally showcasing triple or even quadruple emission at 77 K. This work is anticipated to stimulate research interest in hydride-containing metal nanoclusters, focusing not only on compositional tailoring and structural engineering, but also on electronic structure details and potential applications.