四、 Summary
Our study conclusions can be summarized as follows:
1. Benchmark calculations show that our theoretical results on the spectroscopic constants of are in good agreement with previous theoretical and experimental findings. Our predictions that the salt compound may exist at temperatures lower than −28.39 °C are consistent with the observation that it can be prepared at −40 °C. Our predicted individual ion volumes of the AuXe42+ cation, which are used to estimate lattice energies are in good agreement with the experimental values. The validity of the theoretical calculation methods in the benchmark calculations demonstrated above ensures that our calculation results in this article are reliable.
2. Our calculations show that the corresponding enthalpy change ∆H(2) for MAr42+(Sb2F11−1)2(M=Au,Ag,Cu) could be estimated to be <−15.477, −49.332, and −74.508 kcal/mol, respectively, according to the Born–Haber cycle. MAr42+(Sb2F11−1)2(M=Au,Ag,Cu) salt compounds can be synthesized, and their upper-limit stable temperatures are estimated to be −224.43, −146.21, and −80.39 °C, respectively. The bulk salt compound CuAr42+(Sb2F11−1)2is the most promising candidate for synthesis due to Cu having the largest binding energy with Ar and the smallest ionic radius among the MAr42+(M=Ag,Cu,Au) systems.
3.Our calculations also show that the outlook for synthesizing the salt compounds is obscure.
4. Accurate predictions of the stability of ionic salt compounds should be based on rigorous Born–Haber cycles, and the starting material of the cycles must be stable.