Unveiling distinct bonding patterns in noble gas hydrides via interference energy analysis

Despite their apparent simplicity, the helium hydride ion (HeH⁺) and its analogues with heavier noble gas (Ng) atoms present intriguing challenges due to their unusual electronic structures and distinct ground-state heterolytic bond dissociation profiles. In this work, we employ modern valence bond calculations and the interference energy analysis to investigate the nature of the chemical bond in NgH⁺ (Ng = He, Ne, Ar). Our findings reveal that the energy well formation in their ground-state potential energy curves is driven by a reduction in kinetic energy caused by quantum interference, identical to cases of homolytic bond dissociation. However, clear differences in bonding situation emerge: in HeH⁺ and ArH⁺, electron charge transfer leads to Ng⁺-H covalent bonds, while in NeH⁺, a preferred Ne + H⁺ valence bond structure suggests the formation of a dative bond. This study highlights the distinct bonding mechanisms within the NgH⁺ series, showcasing the interplay between quantum interference and quasi-classical effects in molecules featuring noble gases.