what are the point groups for
mer- Co Cl3 (CO3)
and
fac- Co Cl3 (CO3)
In an octahedral compound with three of one ligand and three of another, there are two geometric isomers: the mer in which each set of three same ligands is in a meridian and the fac in which each set of three is on a face of the octahedron.
So in the case of the mer complex there is a plane of symmetry through the same ligands. Any thoughts on the fac complex?