Photoelectron spectroscopic and computational studies of the Pt@Pb101- and Pt@Pb121-/2- anions

A combination of anion photoelectron spectroscopy and density functional theory calculations has elucidated the geometric and electronic structure of gas-phase endohedral Pt/Pb cage cluster anions. The anions, Pt@Pb-10(1-) and Pt@Pb-12(1-) were prepared from preassembled clusters generated from crystalline samples of [K(2,2,2-crypt)](2)[Pt@Pb-12] that were brought into the gas phase using a unique infrared desorption/photoemission anion source. The use of crystalline [Kd2,2,2-crypt)] (2)[Pt@Pb-12] also provided access to K[Pt@Pb-n](-) anions in the gas phase (i.e., the K+ salts of the Pt@Pb-n(2-) anions). Anion photoelectron spectra of Pt@Pb-10(1-), Pt@Pb-12(1-), and K[Pt@Pb-12](1-) are presented. Extensive density functional theory calculations on Pt@Pb-10(3-/2-/1-/0) and Pt@Pb-12(2-/1-) provided candidate structures and anion photoelectron spectra for Pt@Pb-10(1-) and Pt@Pb-12(1-). Together, the calculated and measured photoelectron spectra show that Pt@Pb-10(1-) and Pt@Pb-12(2-/1-) endohedralcomplexes maintain their respective D-4d and slightly distorted I-h symmetries in the gas phase even for the charge states with open shell character. Aside from the fullerenes, the Pt@Pb-12(2-) endohedral complex is the only bare cluster that has been structurally characterized in the solid state, solution, and the gas phase.