In addition to high thermodynamic stability, these out-of-sample NCBs also show high kinetic stability and correlation between ∆G and ∆G ‡ , as was determined with NCBs in our library (R 2 = 0.92) (Figure , Table ). We also used these novel structures to test our model's performance with out-of-sample structures. All except three of these out-of-sample NCBs showed accurate predictions (< 3 kcal/mol, 12.552 kJ/mol, prediction error), with each poor prediction occurring for structures with out-of-sample R2 groups. The accurate predictions on unseen substructures gives confidence in the predictive ability of our model. Additionally, the model tends to predict stabilities higher than the benchmark DFT calculations, especially for the three out-of-sample structures errors in stability prediction for these out-of-sample structures assume higher stability than calculated using DFT, a trend present for all except one structure. Errors tending this way reduce the chance that synthetic chemists disregard highly stable structures due to our model when choosing stability-ranked NCB candidates to characterize experimentally.