Coarse structure minimization with MMFF94, as implemented in OpenBabel, yielded the initial guess structures. An XTB relaxed surface scan was then used to explore the potential energy surface with respect to rotation around the C-N bond by constraining the appropriate dihedral atoms. Parsing and serialization of atom labels allowed quick identification of specific atoms for the dihedral angle constraints within the scripts. When XTB relaxed surface scan maxima and minima were used as guess structures, we were unable to locate transition states 23, 27, and 29. The inability to converge to transition states may be challenging to rectify manually for large libraries. Molli molecular building capability allows the construction of better transition state guesses by joining the distorted core from a successfully located transition state with an optimized aryl substituent. These structures converged smoothly to the corresponding transition states. The computed barriers were generally close to the experimentally observed ones (Table ), except for 25 and 27. Despite structural similarities between 24 and 25, the latter was overpredicted by 25 kJ mol -1 compared to experimental measurement. The barrier for 27, on the other hand, was underpredicted by 16 kJ mol -1 . We cannot offer a supportable explanation for these outliers. We cautiously speculate that the barrier could potentially exhibit a significant dependence on explicit solvation and/or proton transfer effects.