Besides the most commonly used string-based representations, such as the Simplified Molecular Input Line Entry Specification (SMILES) and fingerprints like the extended connectivity fingerprint (ECFP) , molecules can be directly represented as graphs (Figure ). In graphs, the atoms and bonds are represented as nodes, and edges, respectively . While these kind of representations are well suited for the description of most organocatalysts with distinct bonds, they have limitations when describing coordination compounds as commonly found in transition-metal catalysis for example .