Illustrated Glossary of Organic Chemistry

Stereoisomer (configurational isomer): One molecule in a set of isomers differing in the position of atoms in space, but are not constitutional isomers or conformational isomers. Stereoisomers are either enantiomers or diastereomers.

Stereoisomer examples. Verify with models.

(R)-2-butanol		(S)-2-butanol

(R)-2-butanol and (S)-2-butanol are enantiomers.

(1R,2R)-2-chlorobromocyclohexane		(1S,2R)-2-chlorobromocyclohexane

(1R,2R)-2-chlorobromocyclohexane and (1S,2R)-2-chlorobromocyclohexane are diastereomers.

These representations of cis-1,2-dichlorocyclohexane are identical; they are not stereoisomers. Cis-1,2-dichlorocyclohexane is a meso compound.