Detection and Specification of Chirality

Ligands are ranked in order of decreasing atomic number of the atom directly connected to the stereogenic imit. 

If the relative order of two ligands cannot thus be decided, it is determined by a similar comparison of atomic numbers of the next atoms in the ligands, or, if 

If two atoms have the same atomic number but different mass number, the atom with higher mass number comes first. 

Double and triple bonds are counted as if they were split into two or three single bonds, respectively. 

Early implementations of the CIP rules for computer detection and specification of chirality were described for the LHASA [105], CHIRON [106], and CACTVS [107] software packages. Recently, several commercial molecular editors and visualizers (e.g., CambridgeSoft s ChemOffice, ACD s I-Lab, Accelrys WebLab, and MDL s AutoNom) have also implemented the CIP rules. 

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