Complexes of an argon atom with the linear anions HCC− and HC4−: results of coupled cluster calculations

Large-scale coupled cluster calculations have been carried out for the complexes of an argon atom with the linear anions HCC− and HC4−. In both cases, almost T-shaped structures are energetically favoured. Their equilibrium dissociation energies (De) are predicted to be 501(5) and 507(5) cm−1, respectively. In contrast to the isoelectronic neutral systems Ar + HCN and Ar + HC3N, no energy minima are found for the ‘hydrogen-bonded’ configurations. While the complex Ar ⋯ HCC− is rather flexible, Ar ⋯ HC4− appears to be fairly rigid, quite similar to isoelectronic Ar ⋯ HC3N or Ar ⋯ HC4H.