Geometric and Electronic Properties of P Atom-Doped Al Nanoclusters: Alkaline-like Superatom of P@Al 12 .

The geometric and electronic characteristics of phosphorus-atom doped aluminum nanoclusters, Al n P m ( n = 7-17, m = 1 and 2), were investigated through a combination of experiments and theoretical calculations. The size dependences of the ionization energy ( E i ) for Al n P m NCs exhibit a local minimum of 5.37 eV at Al 12 P 1 , attributed to an endohedral P@Al 12 superatom (SA). This SA originates from an excess electron toward the 2P shell closing (40e), coexisting with an exohedral isomer featuring a vertex P atom. The stability of the endohedral P@Al 12 is further enhanced in its cationic state compared to the exohedral isomer, when complexed with a fluorine (F) atom, forming an SA salt denoted as P@Al 12 + F - with an elevated E i ranging from 6.42 to 7.90 eV. In contrast, for the anionic Al 12 P 1 - , the exohedral form is found to be more stable than the endohedral one using anion photoelectron spectroscopy and calculations. The geometric and electronic robustness of neutral P@Al 12 SAs against electron donation and acceptance is discussed in comparison to rare-gas-like Si@Al 12 SAs.