Optical Isomerism

Two molecules are optical isomers of one another if they are

Here is an example of a pair of optical isomers. The molecular formula is CClBrCH3. This is an example of a molecule in which at least one carbon atom has four different substituents. The first two pictures are static and show the mirror image relationship between the two forms.

The images below are live so that you can rotate them individually to verify that they are indeed optical isomers of one another.

 

Here is an example from transition metal chemistry. The complex contains a Cr(III) ion and three ethylenediamine ligands. The hydrogen atoms in the ethylenediamine ligands have been omitted for the sake of clarity. Verify that these two molecules satisfy both criteria for optical isomerism. The analogy is often given that these two forms can be seen as three propeller blades, "digging into" the plane of the page in different ways. Can you see this here?

 

 

Here is a picture that emphasizes the "propeller-like" nature of these complexes.