Tetrahedral Pt10- Cluster with Unique Beta Aromaticity and Superatomic Feature in Mimicking Methane.

Utilizing a customized metal cluster source in tandem with a flow tube reactor and a reflectron time-of-flight mass spectrometer, we have obtained well-resolved pure metal clusters Ptn- and observed their gas-phase reactions with a few small gas molecules. Interestingly, the remarkable inertness of Pt10- was repeatedly observed in different reactions. Meanwhile, we have determined the structure of Pt10- within a regular tetrahedron. Considering that Pt possesses 5d96s1 electron configuration, the tetrahedral Pt10- exhibits unexpected stability at neither a magic number of valence electrons nor a shell closure of geometric structure. Comprehensive theoretical calculations unveil the stability of Pt10- is significantly associated with the all-metal aromaticity. In addition to the classical total aromaticity, which is mainly due to 6s electrons, there is unique beta-aromaticity ascribed to spin-polarized beta 5d electrons pertaining to singly occupied multicenter bonds. Further, we demonstrate the superatomic feature of such a transition metal cluster Pt10-, as Pt6@Pt4-, in mimicking methane.