REACTIONS BETWEEN H-3+ AND RARE-GAS ATOMS

Quantum chemical calculations have been carried out for the reactions between H-3+ and rare ps atoms X (X = He, Ne, Ar, Kr). These reactions , which lead to protonated rare ps atoms, are all endoergic. This mean s that protonated rare gas atoms are stronger acids than H-3+. The rea ctions proceed via complexes of the H-3+.X type. While H-3+.He is hard ly stable, H-3+.Ar and H-3+. Kr are quite stable. Three equivalent min ima of H-3+.X (C2v symmetry structure in which X aims at the H atoms i n the H-3+ triangle) are separated by three saddle points (also C2v sy mmetry; X aims at the middle of the H-H bond). The calculated barrier height is negligible for the He and Ne complexes and amounts to 4.3 an d 8.1 kcal/mol for the isomerization of H-3+.Ar and H-3+. Kr, respecti vely. Satisfactory agreement is found between the calculated and exper imentally derived properties.