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 Pt-n(-) and observed their gas-phase reactions with a few small gas molecules. Interestingly, the remarkable inertness of Pt-10(-) was repeatedly observed in different reactions. Meanwhile, we have determined the structure of Pt-10(-) within a regular tetrahedron. Considering that Pt possesses 5d(9)6s(1) electron configuration, the tetrahedral Pt-10(-) 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 Pt-10(-) 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 Pt-10(-), as Pt-6@Pt-4(-), in mimicking methane.

Automated summary

By using a customized metal cluster source, the inertness of Pt-10(-) was observed and its tetrahedral structure was determined, suggesting its stability is significantly associated with all-metal aromaticity.