Dicationic Helium Molecular Cluster, He_n²⁺ (n = 4, 5): Noble Gas Analogue of Hydrocarbon

Dicationic noble gas compounds have attracted the attention of chemists for a long time. Herein, dicationic helium tetramer, He₄²⁺, and helium pentamer molecular cluster, He₅²⁺, isoelectronic and isostructural with the simplest hydrocarbon such as methyl cation and methane, respectively, are predicted for the first time. High-level ab initio calculations predict that the proposed cluster is thermodynamically metastable. Detailed bonding analyses reveal that the proposed cluster feature covalent bonds. The present study sheds light on the hitherto unexplored chemistry of covalently bonded noble gas compounds.