# How can I identify and draw the optical isomers for the isomers of [Cr(H_2O)_3Cl_3 ]^+?

Jun 5, 2015

There are two isomers: fac and mer.

"[Cr(H"_2"O)"_3"Cl"_3]^+ has six ligands, so it is an octahedral complex.

There are three ligands of one type and three ligands of another type.

It is classed as an ${\text{MX"_3"Y}}_{3}$ complex, and there are two possible isomers.

In the facial (fac) isomer, each set of three identical ligands occupies one face of the octahedron.

In the meridional (mer) isomer, each set of three identical ligands is arranged in a T-shape in a plane that includes the metal atom.

We can make a model in which green spheres represent $\text{Cl}$ and the white spheres represent $\text{H"_2"O}$.

Then the model below represents fac-"[Cr(H"_2"O)"_3"Cl"_3]^+.

And the model below represents mer-"[Cr(H"_2"O)"_3"Cl"_3]^+.