Quantum mechanical calculations were carried out with the Gaussian 16 program in the gas phase . Geometry optimizations along the reaction pathways were conducted with the M06-2X density functional and the def2-TZVP basis set . Gibbs free energy values were refined with quasi-harmonic (QHA) vibrational corrections to entropy using the GoodVibes program at 1500 K. For more details, see SI H . Each YSI was measured three times and then averaged. The systematic uncertainty in YSI is ± 2%, which is dominated by the uncertainty in the mass densities of the samples. The random uncertainty is ± 4%, which is 2 times the standard deviation of the 26 measurements of the internal standard (SI F). Therefore, the overall uncertainty of the measured YSIs is ± 6%.