Meso compound
From Free net encyclopedia
A Meso compound or meso isomer is a chemical compound with molecules that contain 2 or more asymmetric (chiral) centers but which is optically inactive (or achiral) because it contains an internal plane of symmetry. For example one of the isomers of tartaric acid is a meso compound:
If you rotate the molecule 180° you will have the same apparent stereochemistry. (The bottom must be rotated within the plane of your monitor.)