Cation−Cation π−π Stacking in Small Ionic Clusters of 1,2,4-Triazolium

The existence of cation−cation π−π stacking in the 1,2,4-triazolium−dinitramide tetramer and 1,2,4-triazolium−chloride tetramer (two cations and two anions) is predicted based on the structures optimized using second-order perturbation theory (MP2). In the most stable tetramer structure of 1,2,4-triazolium−dinitramide, π−π stacking is formed with an interplane distance of ∼3.2 A and a parallel displacement of ∼1.4 A. In the most stable tetramer structure of 1,2,4-triazolium−chloride, π−π stacking is formed with an interplane distance of ∼2.9 A and a parallel displacement of ∼1.0 A.