Helionitronium trication (NO2He3+) and helionitrosonium trication (HeNO3+)

The structures and stabilities of helionitronium trication NO2He3+ and heli onitrosonium trication HeNO3+ were calculated at the ab initio MP2/6-31G** level. The C-5 symmetry structure was found to be a minimum for the NO2He3 trication, which is isoelectronic and isostructural with the previously st udied NO2H2+. Dissociation of the C-5 symmetry structure into NO+ and OHe2 is thermodynamically preferred by 183.1 kcal/mol (1 cal = 4.18 J), althoug h a kinetic barrier of 12.4 kcal/mol has to be overcome, The C symmetry str ucture was also found to be a minimum for the HeNO3+ trication.