A Sulfide (Selenide)-Centered Nonanuclear Silver Cluster: A Distorted and Flexible Tricapped Trigonal Prismatic Ag9 Framework

Two luminescent, monoanionic chalcogenide-centered nonanuclear silver clusters stabilized by dichalcogenophosphates were synthesized and fully characterized by various spectroscopies including multinuclear NMR and ESI-mass. Single crystal X-ray diffraction studies on both cluster anions, [Ag-9(S){S2P(OEt)(2)}(8)](-), 1, and [Ag-9(Se){Se2P(OEt)(2)}(8)](-), 2, reveal that the nine silver atoms form an extremely distorted tricapped trigonal prism, which has an encapsulating chalcogenide. The coordination geometry of the central chalcogenide appears to be monocapped trigonal prismatic, which was analyzed by DFT calculations. The origin of the yellow emission is assigned by TDDFT calculations to originate from a chalcogen (ligand + encapsulated) -> silver charge transfer.