Stability against heat-induced dissociation was evaluated using thermogravimetric analysis (TGA). Both clusters underwent three stages of weight loss (Figures and). According to the weight of the ligands and their functional groups, the weight loss at approximately 100 °C is attributed to the removal of SO3 t Bu ligands (theoretical loss = 20% for S@Ag54 and 16% for I@Ag54), while the weight loss at approximately 120 °C is attributed to the removal of t Bu groups from S t Bu ligands (theoretical loss = 11% for both S@Ag54 and I@Ag54). The final weight loss at approximately 180 °C is interpreted as the removal of sulfur (theoretical loss = 6.5% for both S@Ag54 and I@Ag54). The slow weight loss at subsequent temperatures can be attributed to the desorption of sulfur or X from the remaining X@Ag54S20. The dissociation energies of Ag-SO3 t Bu and AgS-t Bu, calculated using density functional theory (DFT), were 54.2 and 57.4 kcal/mol, respectively (Table ). This should be the reason why thermal dissociation occurred in the order.