Results and discussion
Key geometrical parameters for D 3h[MH3M]+ and
[NgMH3MNg]+ cations, optimized at
the all-electron CCSD(T)/cc‑pVQZ level of theory, are presented in Table1 . Our values for the beryllium species are very similar to
those reported by Zhao et al.,[13] with the small
differences being mostly due to the use here of a different basis set.
Whether M is Be or Mg, we observe from Table 1 that the capping ofD 3h[MH3M]+ cations with Ng atoms
leads only to very small increases in the MHM angle and thus in the MM
distances, but it has practically no effect on the MH distances. As such
we can anticipate that the nature of the bonding interactions in the
central MH3M moieties should change relatively little
when the D 3h[MH3M]+ cations are capped with He
or Ne atoms.