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How can I classify the chirality at stereocentres in my structure using Mercury?


Any molecular or crystallographic files displayed in Mercury can be assessed and the observed stereocentres (if any) can be classified as long as the molecular structures visualised have bond types assigned. Any identified stereocentres are assessed using Cahn-Ingold-Prelog (CIP) priority rules (including special CIP rules) to assign an R or S label to each stereocentre. In the case of stereocentres with more than four substituents, an M label (for 'mixed') may be assigned if the order of CIP priorities does not uniformly increase or decrease.

To display the classifications of chiral centres, tick the checkbox "Show Labels for" in Mercury's Labels toolbar, choose "All atoms" from the first drop-down menu and then "Stereochemistry" from the second drop-down menu.