Fig. 9
Standardization failure examples. Each structure is shown as it enters the respective standardization step, including modifications from previous steps. a SID 479450 contains two tetra-valent oxygen atoms (indicated by arrows) and fails the verification of atomic valences. b SID 8021026 contains a penta-valent carbon atom (indicated by arrow) and fails the verification of atomic valences as well. c SID 235635 contains two adjacent nitrogen atoms that both have a positive charge (indicated by arrows). A post-processing evaluation in the determination of a canonical tautomer lets structures fail if they have neighboring charges of the same type