In contrast, the barrier of going from outer-sphere complexes to CIPs is almost changeless with a value of ~10.9 kJ•mol -1 , due to that the outer-sphere complexes gradually become more stable with temperature increasing (Fig. ). However, the thermal energy increases from ~2.5 to ~2.9 to ~3.1 kJ•mol -1 with temperature increasing from 300 to 350 to 373 K. This would increase the transformation probability of going from outer-sphere complexes to CIPs, which is consistent with the experimental results of high temperature promoting the formation of CIPs above, as displayed in Figs. and.