Fig. 33From: PubChem chemical structure standardizationFunctional group standardization IV. Numbers above arrows are transformation indices for respective standardization rules (see the text for the description of transformation indices). a Different representations of cyclopentadiene used in metallocene structures are unified. b Case for benzene analogous to a. c Standardization of thiophene derivatives. Transformation is only successful if implicit hydrogen counts are sufficientBack to article page