Helium hydride cation

Protonation of a helium atom gives He-H+, the helium hydride cation, the simplest heteronuclear molecule [60]. Conceptually, of course, this can also be formed by the union of a helium dication and a hydride ion, or a helium cation and a hydrogen atom ... 

Efhylene alone (15% diluted in helium) does not react in HF-TaF at 40 C to form any propane product but rather forms a complex mixture of unsaturated and higher molecular weight products. Methane also does not react at all under these conditions (27). It should be noted that unless a flow system is used, the propone product, which is a substantially better hydride donor than methane, reacts further with the intermediate ethyl cation to ultimately form ethane and propylene (eq. 2). 

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