Bond lengths and dissociation energy of
The optimized exhibits a square planar D4h symmetry with Au ions in the center connected to the four Xe atoms and has a 2B1gelectronic ground state.Table 2 shows that our theoretically determined equilibrium distance for at the MP2 level is 2.711 Å, which is slightly lower than the experimental value. By contrast, the corresponding B3lyp value is 2.85 Å, which is higher by approximately 0.1 Å compared with the experimental value. We note that the MP2 and B3lyp results for by Seidel(24) using pseudopotentials and small basis sets are 2.871 and 2.787 Å, respectively. Seidel predicted that the bond distances at the B3lyp and MP2 levels are longer than our results by as much as 0.02 and 0.07 Å, respectively, thereby demonstrating the need for large basis sets to describe these weak interaction systems. Li (55) reported that the calculated value (2.714 Å) at the high theoretical level ccsd(T) is nearly identical to the experimental ones. Thus, a high theoretical level ccsd(T) with a large basis set will produce results close to the experimental value limit. However, theoretical level MP2 is an optimal compromise choice between accuracy and cost for our full calculations on weak interaction systems considering computational feasibility. Our result at the MP2 level is reliable.
We now discuss the dissociation energy of . Table 3 shows that is predicted to be stable toward dissociating into Au2+ and 4Xe at all levels of theory employed in our study. The predicted dissociation energy Do corrected by the BSSE and ZPE varies between 189.136 and 238.583 kcal/mol (Table 3). The mean dissociation energy with respect to Au2+ and 4Xe is predicted to be approximately 208 kcal/mol (taking the average of the last two columns in Table 3). This value is a little higher than the 200 kcal/mol mean dissociation energy predicted by Seidel(24). The predicted bond distance (2.891 Å) at the HF level by Seidel is very long. Hence, the 144 kcal/mol dissociation energy calculated at the HF level by Seidel is unreliable and underestimates the mean dissociation energy with respect to Au2+ and 4Xe. Thus, the mean dissociation energy (208 kcal/mol) is reasonable with respect to Au2+ and 4Xe.
Existence and stability prediction ofbased on Born–Haber cycles
A synthetic route according to reaction 1 could be adopted to prepare the salt compound. Figure 1 shows the corresponding Born–Haber cycle.