Incorporation of the TcO Anion within the Ag(C≡CBu) Cluster Unveiling the Unique Shell-to-Core Charge Transfer.

We present the first example of an TcO anion entrapped within the cavity of a silver cluster, revealing an unprecedented photoinduced charge transfer phenomenon. [Ag(C≡CBu)(TcO)]·(BF) (denoted as ) was successfully synthesized and structurally characterized. Single-crystal X-ray diffraction and Raman spectroscopy reveal that the tetrahedral structure of the TcO anion sustains significant symmetry breaking with weakened Tc-O bond strength under confinement within the Ag(C≡CBu) cluster. Notably, exhibits a broadband electronic absorption spectrum in the visible region, which was absent for the other TcO-containing compounds. Density functional theory calculations elucidate that host-guest electrostatic interactions result in an electron polarization effect between the TcO anion core and the Ag cationic shell. The emergence of an absorption band in is rationalized by intermolecular charge transfer from the Ag electronic states to the lowest unoccupied molecular orbitals of TcO instead of the intramolecular electron transition observed in other TcO-containing compounds.