The two reactions, for which the TS search was unsuccessful, are shown in Figure . The product in reaction 16 was the only structure that reacted when optimized with GFN2-xTB. After optimization the product became NH 3 + BH 3 + NH 2 BH 2 and the product is thus not stable on the GFN2-xTB potential energy surface, which can affect the path optimization and thus the TS guess. During the DFT TS optimization the TS guess structure instead goes to the TS of reaction 9 (Table ), which has a ≈ 8 kcal/mol lower barrier than reaction 16. The other reaction not found, reaction 84, is a pretty simple reaction and it is not clear why the TS of this reaction would be difficult to locate. Instead the TS of the reaction in Figure is found every time. Comparing the found TS with the true TS (Figure ) shows that the TSs are quite similar. The important difference seems to be the orientation of the methylene group in the middle.