Complexes of an argon atom with linear cations: results of coupled cluster calculations

Large-scale coupled cluster calculations have been carried out for complexes between an argon atom and four different linear cations (HCNH⁺, HC₃NH⁺, HCCH⁺, and HC₄H⁺). The two former closed-shell species have hydrogen-bonded linear forms, with nitrogen acting as proton donor, as the energetically most stable isomers. Their dissociation energies (D₀) are predicted to be 1261 and , respectively. For Ar?HCCH⁺, the T-form with symmetry is the absolute energy minimum of the potential energy surface, lying below the fragments at infinite separation. Ar?HC₄H⁺ has a dissociation energy less than half as large and slightly prefers the linear structure. Various spectroscopic properties are predicted for the closed-shell complexes under investigation.