Another hydrogenation type involves, formally, H • or H -reacting with sp 2 centers (violet data in Figure ). The TS structures in these elementary steps resemble those in the Felkin-Anh model for nucleophilic addition to carbonyls, This approach to the analysis of BEP relationships diverges from previous studies structures has notably increased the correlation quality. For example, including both sp 2 and sp 3like transition states into BEP relationships for hydrogenation steps increases its RMSD to 0.22 eV from 0.10 and 0.12 eV obtained in Figure . Similarly, clustering of calculated data points according to the TS geometry consistently improves the quality of BEP relations for all types of elementary steps.