Figure shows the breakdown of feature contributions to the principal components used for PCA and UMAP analyses. ATS (autocorrelation of topological structure (moreau-broto)) features dominate the first two principal components. The lag 6 weight is likely due to the tridentate ligand scaffold connections. The bottom of Figure plots the ATS values versus the PCA and UMAP components. These plots demonstrate the variability in ATS values versus components that provides continuous separation of ligands. For us the most important aspect of the ReaLigands library is the ability to use it for rapid evaluation of catalysts with quantum-chemical calculations. Therefore, to demonstrate the utility of this library we used a subset set of the bidentate ligands to generate many Rh-H ethylene migratory insertion transition states and ground states to generate barrier heights. This was done by importing the ReaLigands library into our program Mason that uses Open Babel APIs to add ligands to a frozen transition-state core (one-by-one) and only requires defined connection points between the ligand and metal, which are contained in the ReaLigands files. These built structures are then piped to an automated program to handle structure optimization in Gaussian 16. A diverse random subset of 750 bidentate ligands was generated by calculating the Morgan fingerprints and using a dice similarity score. The M06 49 /def2-SVP method was used to optimize all transition-state and ground-state structures using based on the Rh(H)(ethylene) core obtained from the fully optimized migratory insertion transition state for (Me2PCH2)2Rh(H)(ethylene) (Figure ). Ground state calculations have ethylene removed and therefore barrier heights are relative to the optimized Rh-H intermediate and separated ethylene. All transition states were verified to have a singlet negative vibrational frequency with the correct reaction coordinate motion.