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 ½Kð2,2,2-cryptފ 2 ½Pt@Pb 12 Š that were brought into the gas phase using a unique infrared desorption/photoemission anion source. The use of crystalline ½Kð2,2,2-cryptފ 2 ½Pt@Pb 12 Š also provided access to K½Pt@Pb n Š − anions in the gas phase (i.e., the K þ salts of the Pt@Pb n 2− anions). Anion photoelectron spectra of Pt@Pb 10 1− , Pt@Pb 12 1− , and K½Pt@Pb 12 Š 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− endo-hedral complexes 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. endohedral clusters | negative ions | mass spectrometry T he synthesis, characterization, and solution chemistry of the soluble main group polyanions (i.e., Zintl ions) have a 120-y history (1) that has been well reviewed (2-7). The use of soluble Zintl clusters for the preparation of unique materials was pioneered by Haushalter and O'Connor in the 1980s in their work on magnetic spin glasses, electronic materials, and metallic coatings (8-13). Since that time, scientists have pursued new materials utilizing various Zintl ion precursors to both ionically and cova-lently link the cluster anions into oligomers (14-18), polymers (19, 20), network solids (21-23), and nanomaterials (24-26). Simultaneously, gas-phase chemists have prepared bare (e.g., ligand-free) clusters in molecular beams, studied their size-dependent properties, and explored possible condensed-phased manifestations (27-30). Especially notable was the discovery of C 60 (31) in molecular beam experiments and its subsequent macroscopic synthesis (32). Several other cluster species (not yet assembled into solids) show unusual gas-phase stability (e.g., met-car cages Ti 8 C 12 and Zr 8 C 12 , refs. 33 and 34, and Al 13 1−-type cluster anions comprising icosahedral cages of group 13 elements with one atom inside; i.e., Al@Al 12 1− , refs. 27, 35, and 36). Traditional inorganic cluster compounds are stabilized by li-gand spheres that reduce cluster-core interactions. By contrast, bare gas-phase clusters devoid of ligands are vulnerable to coa-lescence. Combining the attributes of both are salts composed of Zintl cluster anions and their countercations. Not only are Zintl cluster anions ligand free with several structural similarities to gas-phase...

It's platonic: The Pt centered [Pb12]2− icosahedron (depicted) was prepared from the [Pb9]4− Zintl ion and [Pt(PPh3)4] in good yield. The anion has virtual Ih point symmetry and is a rare example of a free‐standing carbon‐free aromatic inorganic cluster.

The cluster [Ni@Pb10](2-), prepared from Pb9(4-) and Ni(COD)2, contains a new Zintl ion subunit, closo-Pb10(2-), centered by a Ni atom.

The ligand-free [Ni2Sn17]4- ion comprises two [Ni@Sn9]2- clusters that share a common vertex. The cluster sequentially loses Sn atoms in the gas phase and shows global exchange of all Sn atoms on the NMR time scale in solution at 60 degrees C. At lower temperatures, the fluxionality is localized to the ends of the cluster and does not involve the central 8-coordinate Sn5 atom.

Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surfaceenhanced Raman scattering (SERS) spectroscopy. Star-shaped gold (Au) NPs were prepared in aqueous solutions by the seed-mediated growth method and tested for Raman enhancement using 2-mercaptopyridine (2-MPy) and crystal violet (CV) probing molecules. For both molecules, the SERS activity of the nanostars was notably stronger than that of the spherical Au NPs of similar size. The Raman enhancement factors (EFs) for 2-MPy on Au nanostars and nanorods are comparable and estimated as greater than 5 orders of magnitude. However, the enhancement for CV on nanostars was significantly higher than for nanorods, in particular at CV concentrations of 100 nM or lower.

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